Foundations of Amateur Radio

Foundations of Amateur Radio Today I'd like to talk about noise, but before I do, I need to cover some ground. Recently I explored the idea that, on their own, neither antenna, nor coax, made a big difference in the potential for a contact when compared to the impact of path loss between two stations. I went on to point out that you'd be unlikely to even notice the difference in normal communications. Only when you're working at the margins, when the signal is barely detectable, would adding a single dB here or there make any potential difference. In saying that, I skipped over one detail, noise. Noise is by definition an unwanted signal that arrives together with a wanted signal at the receiver. In HF communications, noise comes from many sources, the galaxy, our atmosphere, and man-made noise from things like electrical switches, motors, alternator circuits, inverters and computers. The example I used was my 10 dBm beacon being reported by an Antarctic station. My signal report was about 5 dB above the minimum decode level and based on signal path calculations, -129 dBm, or around an S0 signal level. What that statement hides is that this is in the context of a noise level that's lower than -129 dBm. Remember, a negative dBm value means a fraction of a milliwatt. While you're considering that, think of the reality of an Antarctic station. This particular station, "Neumayer III" has three 75 kW diesel generators, a 30 kW wind turbine generator, 20 caterpillar trucks, 10 snowmobiles and 2 snow blowers and computers and technology to support 60 people, in other words, plenty of local noise. This makes it all the more remarkable that my 10 dBm beacon was heard and that there was an amateur there to set-up the receiver in the first place. Before I continue, picture mountain tops peaking through the top of a cloud layer as viewed from the window of an aeroplane. If the cloud layer increases in height, less and less mountain tops are visible, until at some point, only clouds are visible. Alternatively, if the cloud layer descends, more and more of the peaks are visible, until at some point no cloud remains and you see the mountains in all their magnificent glory. In that analogy, mountains represent signals and the cloud layer is the equivalent of the noise floor, and in a similar way, signals can be heard or not, depending on the relationship between the level of noise in comparison to the level of the signal. There's a name for this, it's called the signal to noise ratio or SNR, where a value of 0 dB means that noise and signal are at the same level, negative SNR values mean that the signal is weaker than the noise, positive SNR values means that the signal is stronger than the noise. If you know the power level in dBm for both the noise and the signal, you can subtract the two and end up with the signal to noise ratio. In reality, all receiving stations have to contend with noise. If I arbitrarily set the local noise floor at -100 dBm, somewhere halfway between S4 and S5, I'll mostly get laughed at by many stations, either because it's too high or too low. In case you're wondering, I've worked my station in both S0 noise and S9 noise environments and it's fun trying either and comparing. It's one of the reasons I often use a mobile station, to get away from urban noise around me, and you don't have to go far, a local park might be far enough from local noise to whet your appetite. Besides, -100 dBm is a nice round number to play with. You might recall that a typical path loss number for a 2,500 km contact on HF on the 10m band is about 129 dB. With a noise floor of -100 dBm, we immediately know how much output power is required to be heard above the noise. If the received signal has to be at least more than -100 dBm and we know that the path loss is 129 dB, then our transmitted signal needs to at least be enough to make up the difference. Said differently, if our output power is too low, the signal at the receive station will fall below the noise and they won't be able to hear us. So, if we start at say 30 dBm, have a path loss of 129 dB, we'll end up at -99 dBm, which is 1 dB above -100 dBm. Said in another way, the SNR for this is 1 dB. I'd like you to notice something. I've said nothing about the noise floor at the transmitter. We could have low noise, or horrendous noise, either way, it makes no difference to the receiver. What it hears is entirely dependent on the noise floor at the receiving station. I wonder if that observation changes anything about what you think the impact might be of adding an 18 dBi Yagi to your station? I'm Onno VK6FLAB

Foundations of Amateur Radio Recently I explained some of the reasons why I've shifted to using dBm to discuss power. You might recall that 1 Watt is defined as 1,000 mW and that's represented by 30 dBm. 10 Watts is 40 dBm, 400 Watts, the maximum power output in Australia is 56 dBm and 1,500 Watts, the maximum in the USA, is just under 62 dBm. My favourite power level, 5 Watts, is 37 dBm. I mentioned that using dBm allows us to create a continuous scale between the transmitted power and the received signal. On HF, an S9 report is defined as -73 dBm. Between each S-point lies 6 dB, so an S8 signal is -79 dBm, S7 is -85 dBm and so-on to S0, which is -127 dBm. Said differently, to increase the received signal by one S-point you need to quadruple the power output. Now, let's consider a contact with a 100 Watt station, 50 dBm. Let's imagine that the receiver reports an S8 signal. That means that between a transmitter output of 50 dBm and the received signal at -79 dBm, there's a loss of 129 dB. If we dial the power down to 5 Watts, our 37 dBm will be received at -92 dBm, and earn a S6 report, which, in my experience, is pretty common. If we instead use the maximum power permitted in Australia, we'd gain 6 dB and end up at -73 dBm, or S9. The maximum power output permitted in the United States, 62 dBm, is only 6 dB higher and not even enough to get you "10 over 9" at the other end. At this point I could say, see, "QRP, when you care to send the very least", and be done with it. While it's true in my not so humble opinion, that's not where I'm going with this. That 129 dB of loss is made up of a bunch of things. For example, there's the coax loss at either end, the antenna gain at either end and a big one, the path loss between the two antennas. Let's assume for a moment that coax loss and antenna gain cancel each other out. You might think that's nuts, but consider that 100 m of RG58 coax on the 10m band has a loss of around 8 dB and a dipole has an isotropic gain of 2.15 dBi. In case you're not sure what that means, a dipole has a gain of 2.15 dB over the ideal radiator, a theoretical isotropic antenna. Now it's unlikely that you are going to connect a dipole to 100 m of RG58, so let's say a quarter, or 25 m instead. The coax loss is also quartered, or about 2 dB, which pretty much means that your dipole gain and your coax loss essentially cancel each other out. So, as a working number, assuming both stations are similar and ignoring SWR mismatch, pre-amplifiers, filters, and all manner of other tweaks in the signal path, 129 dB loss is a good starting point to work with. If you use a free space path loss calculator, that's the equivalent of the loss for a 2,500 km contact on HF on the 10 m band. Now, if you were to replace the RG58 with something like RG213 coax, the loss drops from around 2 dB to 0.9 dB, so your signal just increased in strength by 1.1 dB, or not enough to make any difference in this example. Of course there's a benefit in using lower loss coax, I mean, 1.1 dB gain isn't nothing, but it really only matters when the conditions are marginal. If you're going to run your coax to the other side of a paddock, you might discover that your signal changes by a whole S-point, but realistically, most of the time you're not going to notice. Similarly, and perhaps more importantly, in the scheme of things, your antenna is also just fiddling around the edges when compared to the path loss of 129 dB. For example, if you double your antenna gain, you're only seeing an improvement of half an S-point and most likely you won't actually notice. Before you grab the nearest chicken to pluck feathers to come after me with, I'd like to point out that each element on their own has a minimal impact on the total system, but that doesn't mean that improving your station is useless, far from it. If you use quality coax, have an antenna that is performing well, is a good match to your transmitter and coax, use appropriate filters and pre-amplification, you're likely to make more contacts more often, but the bottom line is that you actually need to be on air to make noise and ultimately that's going to represent the biggest improvement in your station performance. Case in point, the other day my WSPR or Weak Signal Reporter beacon, with 10 dBm output, was reported 7,808 km away by DP0GVN, the club station of the German Antarctic Research Station "Neumayer III" in Dronning Maud Land, Antarctica, a first for me. WSPR reported that as a signal of -26 dB. Previously I proved that when WSPR reports -31 dB, about 75% of decodes are successful. In other words, we can think of my report as being 5 dB above the minimum decode level. This is interesting for several reasons, least of which is that a report of -26 dB doesn't appear to have a relationship to anything else, something which I've observed before. Looking further, if we use our notional 129 dB loss figure and start at the beacon power of 10 dBm, we end up at -119 dBm, which

Foundations of Amateur Radio The other day I went looking for a software defined radio or SDR for HF. This happened because all such devices on my desk are rated at higher frequencies and I've still not managed to fix the broken SMA board connector on the transverter I purchased over a year and a half ago. In case you're wondering, the design has two SMA connectors attached at either end of a printed circuit board, also known as a PCB. The board slides into a metal case and both connectors are tightened to either side of the case, which causes the problem when the circuit board is slightly shorter than the case and the nuts pull the connector apart, causing the device to fail. Replacing the SMA board connectors would be relatively simple, but they appear hard to come by and the micro SMA connectors that a friend purchased to help, changed the task into finding adaptors, which I've not managed to solve yet. I'm detailing this all for a purpose, trust me. Anyway, the hunt for an SDR for HF lead me to a project called "Radioberry". It's a design by Johan PA3GSB which is designed to be a so-called "hat" for a Raspberry Pi. Think of it as an expansion card to create functionality, in this case a radio capable of transmitting and receiving on HF, covering 0 to 30 MHz, perfect for my current needs. The design uses a Raspberry Pi computer to power and control the board, including programming the on-board FPGA, accessing the actual data and sharing that with the user, either via a touch screen, or using USB, Ethernet, Bluetooth or Wi-Fi. The board itself has two external connectors, one for transmit, one for receive and when you combine it with the Pi, fits neatly into a box which you could 3D print. Amplifier and band filters are left as an exercise to the enterprising amateur, though there is an amplifier design on the github repository. If you're curious, it's based on the work by the Hermes Lite 2 group. Johan specifically doesn't sell this device, instead you can choose to buy it from other enterprising individuals, or better still, build your own. Over the last few years I've started noticing several people in the so-called maker community, people, who a lot like radio amateurs, build stuff for fun, using online printed circuit board services. If you're unfamiliar with the concept, you can design a schematic, layout a PCB, have it manufactured and optionally even built and sent to you. To get an idea of what this might look like, I picked a random online supplier, uploaded the specifications for a Radioberry and costed the whole thing. Suffice to say that the biggest charge is the $50 set-up fee. Any enterprising engineer would have punched the "Buy Now" button and be done with it, but in some things I'm pretty cautious, so I haven't, yet. I don't know enough about the design or schematic to know how it works, to troubleshoot it, to fix any potential issues, or even to know what kinds of issues there might be, even if they're obvious to anyone with electronics experience. To make it clear, my electronics experience is rudimentary at best. I'm comfortable with block diagrams, understand the basic principles behind most passive elements, but if you're going to get into trace length and signal timing, I'm not anywhere even remotely qualified to troubleshoot, let alone spot problems. That's not to say that I am stopping before I start, the opposite is true. I'm using this as an experience to gently get my feet wet. Back to the apparently too detailed explanation of the transverter. Joining the dots you can probably guess where I'm going with this. Given the access to countless documented transverter designs, I feel comfortable enough to work on a design, construct a PCB and have it manufactured. At the rate I'm going, that should get a solution before I can find a PCB edge-mounted SMA connector, well, at least that's my excuse. I'm also eyeing off this same process to build a logging volt meter, since the Internet seems to believe that I should pay hundreds of dollars for a volt meter and an I/O port, even if the chip inside costs all of $6. Oh, the transverter I purchased a year and a half ago costs three times as much as having five of them built on demand, so there's that. For all my life I've been a firm believer in software. I've also been on a computer driven manufacturing journey for a couple of years, still in the process of commissioning my new toys, much to the merriment of some of my fellow amateurs and the idea that I can have a circuit design built and shipped to my door just makes me tingle with anticipation. If you're already ahead of me on this journey, please don't hesitate to point at any potholes on the road and if you're following along, if you break it, you get to keep both parts. I'm Onno VK6FLAB

Foundations of Amateur Radio If you've been following my amateur radio journey, you'll have likely noticed that I've been straying from the fold. The words I use for power have been changing. I've reduced references to Watt and increased use of the term decibel. Initially this was incidental, recently it's been more of a deliberate decision and I'd like to explain how this came to be. It starts with representing really big and really small numbers. Let's start big. On 14 September, 2015 the first direct observation of gravitational waves was made when a pair of black holes with a combined estimated weight of 65 solar masses merged. The signal was named GW150914, combining "Gravitational Wave" and the observation date to immortalise the event. Following the collision, it was estimated that the radiated energy from the resulting gravitational waves was 50 times the combined power output of all the light from all the stars in the observable universe. As a number in Watts, that's 36 followed by 48 zeros. If you're curious, there's even a word for that, 36 Quindecillion Watts. Now let's look at small. The typical signal strength received from a GPS satellite, like say by your phone, is about 178 attowatts, or in Watts, 0.000 and so on, in all, 13 zeros between the decimal point and then 178. What if I told you that the energy associated with the collision of those two black holes could be expressed in comparison with a milliwatt. Remember, this collision emitted more energy than all the output of light from all the stars in the observable universe. The expression for all that power is 526 dBm. Similarly, the tiny received GPS signal can be expressed as -127.5 dBm. Just let that sink in. All the power in the observable universe through to the minuscule power received by the GPS in your phone, all expressed between 526 dBm and -127.5 dBm, and not a zero in sight. As I mentioned, the unit dBm relates to a milliwatt. As a starting point, let me tell you that 1 Watt is 1,000 milliwatts and is represented by 30 dBm. The decibel scale doesn't work quite the same as other number ranges you might be used to. Adding the value 3 doubles its size and adding the value 10 increases its size by a factor 10. For example, to double power from 1 Watt or 30 dBm, add 3 and get 33 dBm, which is the same as 2 Watts. If you want to increase 1 Watt by a factor 10, again, starting with 30 dBm, add 10 and get 40 dBm which is 10 Watts. Similarly, 50 dBm is 100 Watts and 60 dBm is 1,000 Watts. Going the other way, halving power, remove 3. So taking 3 from 60 dBm is 500 Watts or 57 dBm. Dividing power by a factor 10 works the same, take 10. So 47 dBm is 50 Watts and 37 dBm is 5 Watts. If you get lost, remember, dBm relates to a milliwatt. 1 Watt is 1,000 milliwatts and is represented by 30 dBm. Divide by a factor 1,000, remove 30 and end up with 0 dBm, which is the same as 1 milliwatt. I'll say that again, 0 dBm is the same as 1 milliwatt. It takes a little getting used to, but you can do some nifty things. For example, remove 10 to get a tenth of a milliwatt, or -10 dBm. This same process of adding and subtracting applies in other ways too. Attenuation, or making a signal weaker, and amplification, or making a signal stronger can use the same rules. For example, if you apply 3 dB of attenuation, you're making the signal 3 dB weaker, or halving it, so you subtract 3 dB from your power output. If your amplifier is rated at 6 dB gain, you're quadrupling the output and you add 6 dB to your power output. Similarly, if you talk about the gain of an antenna, you add it. If the gain is 20 dBi, you add it to the power output. You can use this for coax loss calculations as well. A 100m length of RG-58 at 28 MHz has a loss of 8 dB. You can directly subtract this from the power output of the transmitter and know precisely how much power is making it to the antenna. There's more. The radio amateur S9 signal strength on HF, something which we consider to be a strong signal, can be expressed as -73 dBm or a very small fraction of a milliwatt. An S8 signal is 6 dB weaker, or -79 dBm. A 20 over 9 report is -53 dBm. I will point out that this is at 50 Ohm. As a result, we now have a continuous scale for all the elements in the transmission chain between the transmitter and the receiver. While I'm here, I've already mentioned that negative dBm readings relate to fractions of a milliwatt, so values between 0 and 1. This highlights one limitation of this scale. We cannot represent 0 Watts. Mind you, that doesn't happen all that often. The thermal noise floor in space at 1 Hz bandwidth, that's at 4 kelvins, is -192.5 dBm, which practically means the minimum level of power we need to express. It's also a good value to remember because if you're doing funky calculations and you end up with a number less than -192.5 dBm, you can pretty much guarantee that you've probably made a boo-boo. 0 Watts using the dBm scale is represented by negative infinity, or essentiall

Foundations of Amateur Radio Between decibels and milliwatts ... As you might recall, I've been working towards using a cheap $20 RTL-SDR dongle to measure the second and third harmonic of a handheld radio in an attempt to discover how realistic that is as a solution when compared to using professional equipment like a Hewlett Packard 8920A RF Communications Test Set. I spent quite some time discussing how to protect the receiver against the transmitter output and described a methodology to calculate just how much attenuation might be needed and what level of power handling. With that information in-hand, for reference, I used two 30 dB attenuators, one capable of handling 10 Watts and one capable of handling 2 Watts. In case you're wondering, it's not the dummy load with variable attenuation that I was discussing recently. I ended up using a simple command-line tool, rtl-power, something which I've discussed before. You can use it to measure power output between a set of frequencies. In my case I measured for 5 seconds each, at the base frequency on the 2m band, on the second and on the third harmonic and to be precise, I measured 100 kHz around the frequencies we're looking at. This generated a chunk of data, specifically I created just over a thousand power readings every second for 15 seconds. I then put those numbers into a spreadsheet, averaged these and then charted the result. The outcome was a chart with three lines, one for each test frequency range. As you'd expect, the line for the 2m frequency range showed a lovely peak at the centre frequency, similarly, there was a peak for the other two related frequencies. The measurement data showed that the power measurement for 146.5 MHz was nearly 7 dB, for 293 MHz it was -44 dB and for 439.5 MHz it was -31 dB. If you've been paying attention, you'll notice that I used dB, not dBm or dBW in those numbers, more on that shortly. From a measurement perspective we learnt that the second harmonic is 51 dB below the primary power output and the third harmonic was about 38 dB below the primary power output. First observation to make is that these numbers are less than shown on the HP Test Set where those numbers were 60 dB and 62 dB respectively. Second observation, potentially more significant, is that pesky dB thing I skipped over earlier. If you recall, when someone says dB, they're referring to a ratio of something. When they refer to dBm, they're referring to a ratio in relation to 1 milliwatt. This means that when I say that the power reading was 7 dB, I'm saying that it's a ratio in relation to something, but I haven't specified the relationship. As I said, that's on purpose. Let me explain. When you use an RTL-SDR dongle to read power levels, you're essentially reading numbers from a chip that is converting voltages to numbers. In this case the chip is an Analog to Digital Converter or an ADC. At no point has any one defined what the number 128 means. It could mean 1 Volt, or it could mean 1 mV, or 14.532 mV, or something completely different. In other words, we don't actually know the absolute value that we're measuring. We can only compare values. In this case we can say that when we're measuring on the 2m band we get a range of numbers that represent the voltage measured along those frequencies. When we then measure around the second harmonic, we're doing the same thing, possibly even using the same scale, so we know that if we get 128 back both times we might assume the voltage is the same in both cases, we just don't actually know how much the voltage is. We could say that there's no difference between the two, or 0 dB, but we cannot say how high or low the voltage is. This is another way of describing something I've discussed before, calibration. So, if I had a tool that could output a specific, known RF power level, and fed that into the receiver and measured, I could determine the relationship between my particular receiver and that particular power level. I could then measure at all three frequencies and determine if the numbers were actually the same for these three frequencies, which is what I've been assuming, but we don't actually know for sure right now. So, at this point we need a known RF signal generator. The list of tools is growing. I've already used a NanoVNA to calibrate my attenuators and I've used a HP RF Communications Test Set to compare notes with. At this point you might realise that we're not yet able to make any specific observations about using a dongle to make harmonic measurements, but you can make pretty pictures... There's a good chance that you're becoming frustrated with this process, but I'd like to point out that at the beginning of this journey I can tell you that I had no idea what the outcome might be and obviously, that's the nature of experimentation. If you have some ideas on how to explore further, feel free to get in touch. I'm Onno VK6FLAB

Foundations of Amateur Radio Over the weekend a friend of mine convinced me to help plant some trees. Mind you, I was told that this was going to be a blue tree painting day. The Blue Tree Project is now a global awareness campaign that paints dead trees blue to spread the message that "it's OK to not be OK", and help break down the stigma that's still largely attached to mental health. In the process, I learnt that my physical stamina is not what it once was and my current appetite for bending over and shovelling dirt is, let's call it, muted. After the digging and the sausage sizzle under the branches of an actual blue tree, there was some opportunity for playing radio, something I haven't done in much too long. I wasn't sure when I last got into the fresh air to actually listen, but I must confess, the coax cable that I picked up out of my shed had been hanging there for several years. The location where we planned to play was in a rural setting, right next to a dam, which surprisingly actually had water in it. The idea was to set-up a vertical antenna with a couple of ground radials, plug in a radio and have a listen. I have to say, after the digging I was really looking forward to this. My piece of coax, about 20 meters long, was used to connect the antenna to the radio so we could sit in the shade whilst the antenna stood out in the sun near the dam. The antenna, a telescopic one, came with a ground spike and about eight radials and needed to be tuned to some extent, as-in, near-enough is close enough, since we had an antenna tuner with our radio. To achieve the tuning we wanted to connect a NanoVNA to the coax which was the first challenge. The BNC connectors on my coax were pretty dull, likely a combination of poor quality, accumulated dust, humidity and lack of use. As an added bonus the centre pin on one end seemed a little bent. After working out how to get an SMA adaptor into the connectors we were in business. Connected up between the antenna and the NanoVNA we set out to get things lined up. The SWR on the display, hard to read in the full sun at the best of times, seemed to be a little odd. Not something I could put my finger on, but if you've seen enough SWR plots you know what it's supposed to look like and for some reason it didn't. We bravely carried on, connected the radio to the coax and started tuning around. Didn't seem to be a lot of activity on the 20m band. We couldn't hear the local NCDXF beacon which was odd. Also no FT8 activity, also odd. If anything, it seemed like there was nothing happening at all. Before we continue, I'll point out that this can happen with a big enough burp from the Sun. I hadn't seen any alerts, so I wasn't buying it. We removed my coax, plugged in something much shorter and the bands came alive with all the activity we'd been expecting. And then it started to rain. Seriously. Finally got out into the world, got radio activity going, had actual signals to tune to and it starts raining. Glynn VK6PAW and I took one look at each other, shook our heads and dashed for the radio to bring it under shelter. I put on my raincoat, and together we disassembled the antenna and the station and went home. Clearly, my coax was faulty. Lesson learnt. Test your coax before you go out and you'll have a better outcome. About that. Today, a week later, I'm sitting on the floor of my shack with the offending coax between my legs, surrounded by adaptors, a NanoVNA, a RigExpert, a dummy load, a short and an open terminator. No matter how I test, no matter what I test, everything is as it should be. I can tell you that the Time Domain Reflectometry shows me that the coax is 25.8m long, useful information, but not really any surprise. There's also no significant return loss, unless you head for 1 GHz, but even then it's perfectly respectable, if anything, better than I expected. There are no loose connections, nothing rattling, nothing amiss. The only thing that I can even begin to think might be the case is that one of the centre pins on one end of the coax is slightly shorter. Combined with "close enough is good enough" when I attached the SMA adaptor in the field, might account for a connection that never got made, since the adaptor wasn't seated deep enough. So, I'm not quite ready to cut off the connectors and re-terminate this coax. I'll be taking it into the field again, but I'll make sure that I bring an alternative, just in case. I'm also leaving the SMA adaptors connected to the coax. Future me will thank me. Oh, yes, in-case you're wondering, I'm slowly working out how to improve my stamina. That was not fun. If you want to know more about Blue Trees and its message, check out the BlueTreeProject.com.au website and if you ever just want to talk, get in touch. I'm Onno VK6FLAB

Foundations of Amateur Radio Before we start I should give you fair warning. There are many moving parts in what I'm about to discuss and there's lots of numbers coming. Don't stress too much about the exact numbers. In essence, what I'm attempting is to explore how we can reduce the power output from a transmitter in such a way that it doesn't blow up a receiver whilst making sure that the signal is strong enough that we can actually measure it. With that in mind, recently I discussed the idea of adding a series of attenuators to a transmitter to reduce the power output by a known amount so you could connect it to a receiver and use that to measure output power at various frequencies. One hurdle to overcome is the need to handle enough power in order to stop magic smoke from escaping. None of my attenuators are capable of handling more than 1 or 2 Watts of power, so I cannot use any of them as the first in line. As it happens, a good friend of mine, Glynn VK6PAW, dropped off a device that allows you to divert most of the power into a dummy load and a small amount into an external connector. In effect creating an inline attenuator capable of handling 50 Watts. The label doesn't specify what the attenuation is, so I measured it using a NanoVNA. To make our job a little interesting, it isn't constant. Between 10 kHz and 1 GHz, the attenuation decreases from 70 dB to 10 dB. We want to measure at a base frequency on the 2m band and its second and third harmonic. The attenuation at those frequencies varies by 11 dB, which means we'll need to take that into account. So, let's subject our currently imaginary test set-up to some sanity checking. Our receiver is capable of reading sensible numbers between a signal strength of -127 dBm and -67 dBm and we'll need to adjust accordingly. If we transmit an actual 20 Watt carrier, that's 43 dBm. With 110 dB of attenuation, we end up at -67 dBm, which is right at the top end of what we think the receiver will handle. If we're using something like 5 Watts, or 37 dBm, we end up at -73 dBm, which is well above the minimum detectable signal. Our best harmonic measurement was around -30 dBm, which means that with 110 dB of attenuation, we end up at -140 dBm, which is 13 dB below what we think we can detect. So, at this point you might wonder if this is still worth our while, given that we're playing at the edges and to that I say: "Remind me again why you're here?" First we need to attenuate our 20 Watts down to something useful so we don't blow stuff up. Starting with 110 dB attenuation, we can measure our base carrier frequency and its harmonics and learn just how much actual power is coming out of the transmitter. Once we know that, we can adjust our attenuation to ensure that we end up at the maximum level for the receiver and see what we are left with. So, let's look at some actual numbers, mind you, we're just looking at calculated numbers, these aren't coming from an actual dongle, yet. Using Glynn's dummy load as the front-end, at 146.5 MHz, the attenuation is about 30 dB. If we look at a previously measured handheld and rounding the numbers, it produced 37 dBm. That's the maximum power coming into our set-up. With 30 dB of attenuation from Glynn's dummy load, that comes down to 7 dBm. We'll need an additional 74 dB of attenuation to bring that down to -67 dBm, in all we'll need 104 dB of attenuation. The third harmonic for that radio was measured at -26 dBm. So, with a 104 dB of attenuation that comes out at -130 dBm, which is below the minimum detectable signal supported by our receiver. However, remember that I told you that our dummy load had different attenuation for different frequencies? In our case, the attenuation at 439.5 MHz is only 19 dB, not 30, so in actual fact, we'd expect to see a reading of -119 dBm, which is above the minimum detectable signal level. I realise that's a lot of numbers to digest, and they're specific to this particular radio and dummy load, but they tell us that this is possible and that we're potentially going to be able to measure something meaningful using our receiver. I'll also point out that if you're going to do this, it would be a good idea to take notes and prepare what numbers you might expect to see because letting the magic smoke escape might not be one of your desired outcomes. Speaking of smoke, what happens if you consider changing the attenuation when you're measuring at another frequency, like say the second or third harmonic and you see a reading close to, or perhaps even below the detectable signal level as we've just discussed. You might be tempted to reduce the attenuation to increase the reading, but you need to remember that the transmitter is still actually transmitting at full power into your set-up, even if you're measuring elsewhere. This is why for some radios you'll see a measurement that states that the harmonics are below a certain value because the equipment used doesn't have enough range to provide an ac

Foundations of Amateur Radio Recently I had the opportunity to use a piece of professional equipment to measure the so-called unwanted or spurious emissions that a transceiver might produce. In describing this I finished off with the idea that you could use a $20 RTL-SDR dongle to do these measurements in your own shack. I did point out that you should use enough attenuation to prevent the white smoke from escaping from your dongle, but it left a question, how much attenuation is enough? An RTL-SDR dongle is a USB powered device originally designed to act as a Digital TV and FM radio receiver. It's normally fitted with an antenna plugged into a socket on the side. I'll refer to it more generically as a receiver because much of what we're about to explore is applicable for other devices too. Using your transceiver, or transmitter, as a signal source isn't the same as tuning to a broadcast station, unless you move it some distance away, as-in meters or even kilometres away, depending on how much power you're using at the time. Ideally we want to connect the transmitter output directly to the receiver input so, at least theoretically, the RF coming from the transmitter stays within the measuring set-up between the two devices. Assuming you have a way to physically connect your transmitter to your receiver we need to work out what power levels are supported by your receiver. For an RTL-SDR dongle, this is tricky to discover. I came across several documents that stated that the maximum power level was 10 dBm or 0.01 Watt, but that seemed a little high, since an S9 signal is -73 dBm, so I kept digging and discovered a thoughtful report published in August 2013 by Walter, HB9AJG. It's called "Some Measurements on DVB-T Dongles with E4000 and R820T Tuners". There's plenty to learn from that report, but for our purposes today, we're interested in essentially two things, the weakest and strongest signals that the receiver can accommodate. We're obviously interested in the maximum signal, because out of the box our transmitter is likely to be much too strong for the receiver. We're going to need to reduce the power by a known amount using one or more connected RF attenuators. At the other end of the scale, the minimum signal is important because if we add too much attenuation, we might end up below the minimum detectable signal level of the receiver. Over the entire frequency range of the receivers tested in the report the minimum varies by about 14 dB, so let's pick the highest minimum from the report to get started. That's -127 dBm. What that means is that any signal that's stronger than -127 dBm is probably going to be detectable by the receiver and for some receivers on some frequencies, you might be able to go as low as -141 dBm. At the other end of the scale the report shows that the receiver range is about 60 dB, which means that the strongest signal that we can use is -67 dBm before various types of distortion start occurring. For comparison, that's four times the strength of an S9 signal. So, if we have a 10 Watt transmitter, or 40 dBm, we need to bring that signal down to a maximum of -67 dBm. In other words we need at least 107 dB of attenuation and if we have a safety margin of two, we'll need 110 dB of attenuation, remember, double power means adding 3 dB. So, find 110 dB of attenuation. As it happens, if I connect most of my attenuators together, I could achieve that level of attenuation, but there's one further issue that we'll need to handle and that's power. As you might recall, an attenuator has several attributes, the most obvious one is how much attenuation it brings to the party. It's specified in dB. My collection of attenuators range from 1 dB to 30 dB. Another attribute is the connector it comes with, I have both N-type and SMA connectors in my collection, so I'll need some adaptors to connect them together. One less obvious and at the cheap end of the scale, often undocumented, aspect of an attenuator is its ability to handle power. Essentially we're turning an RF signal into heat, so an attenuator needs to be able to dissipate that heat to handle what your transmitter is throwing at it. I said that from a safety perspective I'd like to be able to handle 20 Watts of power. Fortunately we don't need all our attenuators to be able to handle 20 Watts, just the first one directly connected to the transmitter. If we were to use a 20 Watt, 30 dB attenuator, the signal through the attenuator is reduced to 0.02 Watts and the next attenuator in line only needs to be able to handle that power level and so-on. To get started, find about 110 dB of attenuation, make sure it can handle 20 Watts and you can start playing. Before you start keying up your transmitter, how might you handle a range of different transmitters and power levels and can you remove an attenuator when you test on a different frequency? On that last point, let me say "No", you cannot remove the attenuator when you're measuring a differe

Foundations of Amateur Radio At a recent local HAMfest we set-up a table to measure second and third harmonic emissions from any handheld radio that came our way. The process was fun and we learnt lots and in due course we plan to publish a report on our findings. When we received a handheld, we would disconnect the antenna, and replace it with a short length of coax and connect it to a spectrum analyser. We would then trigger the Push To Talk, or PTT button and measure several things. We'd record the actual frequency and how many Watts that the transmitter was producing and then record the power level in dBm for the base frequency, double that frequency and triple that frequency. In other words, we'd record the base, second and third harmonics. This resulted in a list of numbers. Frequency and power in Watts are obvious, but the three dBm numbers caused confusion for many visitors. The most perplexing appeared to be that we were producing negative dBm numbers, and truth be told, some positive ones as well, we'll get to those in our report. How can you have negative power you ask? As I've discussed before. A negative dBm number isn't a negative value of power, it's a fraction, so, -30 dBm represents 0.000001 Watts and you'd have to admit that -30 dBm rolls off the tongue just a little easier. What we measured and logged was the overall transmitter output and at specific frequencies. As I've discussed previously, if you transmit using any transceiver, you'll produce power at the intended frequency, but there will also be unintended or unwanted transmissions, known as spurious emissions. The International Telecommunications Union, or ITU, has standards for such emissions. In Australia the regulator, the ACMA, uses the ITU standard for radio amateurs, but I should point out that this might not be the case where you are. It's entirely possible, and given human diversity, probable even, that there are places where there are more stringent requirements, so bear that in mind. I'll state the standard and then explain. For frequencies greater than 30 MHz, the spurious emission must not exceed the lesser of 43 + 10 * log (power) or 70 dB. That might sound like gobbledegook, so let's explore. First thing to notice is that this is for transmissions where the transmitter is tuned to a frequency greater than 30 MHz, there's a separate rule for frequencies less than 30 MHz and the ITU also specifies a range of different limits for special purpose transmitters like broadcast radio and television, space services, and others. Second thing is that the spurious emissions are calculated based on total mean output power. This means that your spurious emissions are considered in relation to how much power you're using to transmit and it implies that for some transmitters you can be in compliance at one power level, but not at another, so keep that in mind. The phrase "the lesser of", means that from a compliance perspective, there's a point at which power levels no longer determine how much attenuation of spurious emissions is required. You can calculate that point. It's where our formula hits 70 dB, and that is at 500 Watts. In other words, to meet the ITU standard, if you're transmitting with less than 500 Watts, you're subject to the formula and if you're transmitting with more than 500 Watts, you're required to meet the 70 dB standard. It means that, at least in Australia, spurious emissions for amateurs are dependent on transmitter power because the maximum permitted power is currently 400 Watts for an amateur holding a so-called Advanced License. Now I'll also point out explicitly that the emission standards that the ITU specifies are for generic "radio equipment", which includes amateur radio, but also includes anything else with a transmitter. One thing to mention is that spurious emissions aren't limited to the second and third harmonics that we measured, in fact they're not even limited to harmonics. If you're using a particular mode then anything that's transmitted outside the bandwidth of that mode is considered a spurious emission and there are standards for that as well. As an aside, it was interesting to me that in many cases amateur radio is treated separately from other radio services, but the ITU considers our community just one of several spectrum users and it's good to remember that the entire universe is playing in the same sandbox, even if only some of it is regulated by the ITU and your local regulator. So, let's imagine that you have a handheld radio that has a total mean power output of 5 Watts. When you calculate using the formula, you end up at 50 dB attenuation. In other words, the spurious emissions may not exceed -13 dBm. So, if your radio measures -20 dBm on the second harmonic, it's compliant for that harmonic, but if it measures -10 dBm, it's not. I should also point out that this is for each spurious emission. About half the radios we tested had a second harmonic that was worse than the third har

Foundations of Amateur Radio There's nothing quite as satisfying as the click of a well designed piece of equipment. It's something that tickles the brain and done well it makes the hairs stand up on the back of your neck. If time was on my side and I wasn't going somewhere else with this, I'd now regale you with research on the phenomenon, I'd explore the community of people building mechanical keyboards and those who restore equipment to their former glory, instead I'm encouraging you to dig whilst I talk about the second and third harmonics. This is about amateur radio after all. Over the years there has been a steady stream of commentary around the quality of handheld radios. Some suggest that the cheaper the radio, the worse it is. Given that these kinds of radios are often the very first purchase for an aspiring amateur it would be useful to have a go at exploring this. When a radio is designed the aim is for it to transmit exactly where it's intended to and only there. Any transmission that's not where you plan is considered a spurious emission. By carefully designing a circuit, by adding shielding, by filtering and other techniques these spurious emissions can be reduced or eliminated, but this costs money, either in the design stage, or in the cost of materials and manufacturing. It's logical to think that the cheaper the radio, the worse it is, but is it really true that a cheap radio has more spurious emissions than an expensive one? To give you an example of a spurious emission, consider an FM transmitter tuned to the 2m amateur band, let's say 146.5 MHz. If you key the radio and all is well, the radio will only transmit at that frequency, but that's not always the case. It turns out that if you were to listen on 293 MHz, you might discover that your radio is also transmitting there. If you're familiar with the amateur radio band plan, you'll know that 293 MHz is not allocated as an amateur frequency, so we're not allowed to transmit there, in fact, in Australia that frequency is reserved for the Australian Department of Defence, and there's an additional exclusion for the Murchison Radio-astronomy Observatory. 293 MHz isn't a random frequency. It's twice 146.5 MHz and it's called the second harmonic. There's more. If you multiply the base frequency by three, you end up at 439.5 MHz, the third harmonic. In Australia, that frequency falls into the amateur allocation as a second use, its primary use is again the Department of Defence. These two transmissions are examples of spurious emissions. To be clear, the transmitter is tuned to 146.5 MHz and these unintended extra signals come out of the radio at the same time. This is bad for several reasons, legal and otherwise. The first, obvious one, is that you're transmitting out of band, which as an amateur you already have no excuse for, since getting your license requires you to understand that this is strictly not allowed. The International Telecommunications Union, or ITU, has specific requirements for what's permitted in the way of spurious emissions from an amateur station. Spurious emissions also mean that there is energy being wasted. Instead of the signal only coming out at the intended frequency, some of it is appearing elsewhere, making the 5 Watts you paid for less effective than you hoped for. So, what's this got to do with the click I started with? Well, thanks to Randall, VK6WR, I have on loan a heavy box with a Cathode Ray Tube or Green CRT screen, lots of buttons and knobs and the ability to measure such spurious emissions. It's marked "HP 8920A RF Communications Test Set". Using this equipment is very satisfying. You switch it on and a fan starts whirring. After a moment you hear a beep, then the screen announces itself, almost as-if there's a PC in there somewhere - turns out that there is and the beep is the Power On Self Test, or POST beep. Originally released in 1992, this magic box can replace 22 instruments for transceiver testing. I started downloading user manuals, oh boy, there's lots to learn. Bringing back lots of memories, it even has a programming language, Instrument BASIC, to control it. Where have you been all my life? Turns out that in 1992 this piece of kit cost as much as my car. Anything for the hobby right? At the next HAMfest I'll be using it to measure as many handhelds as I can get my hands on and taking notes. I have no idea how many I'll be able to test, but I'm looking forward to putting some numbers against the repeated claims of quality and price. I can tell you that a couple of weeks ago I got together with Randall and Glynn VK6PAW and spent an enjoyable afternoon testing several radios and there are some surprising results already. Perhaps this is something you might attempt at your next community event, gather data, rather than opinions... I'm Onno VK6FLAB

Foundations of Amateur Radio If you walk into your radio shack and switch on a light, the result is instantaneous, one moment it's dark, the next it's not. What if I told you that as immediate as it appears, there is actually a small delay between you closing the circuit and the light coming on. Likely the distance between your switch and your light is less than say 10 meters, so the delay is likely to be less than 33 nanoseconds, not something you'd notice unless you're out to measure it. What if your light switch is 3,200 km away? That's the length of the first transatlantic telegraph cable in 1858. Let's start with the notion that between the action of closing a switch, or applying a voltage at one end of the cable and it being seen at the other end takes time. If we ignore the wire for a moment, pretending that both ends are separated by vacuum, then the delay between the two ends is just over 10 milliseconds because that's how long it takes travelling at the speed of light. One of the effects of using a cable is that it slows things down. In case you're curious, the so-called Velocity Factor describes by how much. A common Velocity Factor of 66 would slow this down by 66%. This means that there is a time when there is voltage at one end and no voltage at the other. There are a few other significant and frequency dependent things going on, we'll get to them, but before we go any further, it's important to consider a couple of related issues. Ohm's Law, which describes the relationship between voltage, current and resistance in an electrical circuit was first introduced in 1827 by Georg Ohm in his book: "The Galvanic Chain, Mathematically Worked Out". Initially, his work was not well received and his rival, Professor of Physics Georg Friedrich Pohl went so far as to describe it as "an unmistakable failure", convincing the German Minister for Education that "a physicist who professed such heresies was unworthy to teach science." Although today Ohm's Law is part and parcel of being an amateur, it wasn't until 1841 that the Royal Society in London recognised the significance of his discovery, awarding the Society's oldest and most prestigious award, the Copley Medal, in recognition for "researches into the laws of electric currents". I'll point out that Ohm only received recognition because his work was changing the way people were starting to build electrical engines and word of mouth eventually pressured the Royal Society into the formal recognition he deserved. I also mentioned the speed of light in relation to the delay between applying a voltage and it being seen at the other end, but it wasn't until 1862 when James Clerk Maxwell published a series of papers called "On Physical Lines of Force" that light speed was actually derived when he combined electricity and magnetism and proved that light was an electromagnetic wave, and that there were other "invisible" waves, which Heinrich Rudolph Hertz discovered as radio waves in 1888. How we understand transmission lines today went through a similar discovery process. Your radio is typically connected to an antenna using a length of coaxial cable, which is a description for the shape the cable has, but the nature of the cable, what it does, is what's known as a transmission line. If you looked at the submarine telegraph cable of 1858, you'd recognise it as coaxial cable, but at the time there wasn't much knowledge about conductance, capacitance, resistance and inductance, let alone frequency dependencies. James Clerk Maxwell's equations weren't fully formed until 1865, seven years after the first transatlantic telegraph cable was commissioned and the telegraph equations didn't exist until 1876, 18 years after the first telegram between the UK and the USA. In 1854 physicist William Thomson, was asked for his opinion on some experiments by Michael Faraday who had demonstrated that the construction of the transatlantic telegraph cable would limit the rate or bandwidth at which messages could be sent. Today we know William Thomson as the First Lord Kelvin, yes, the one we named the temperature scale after. Mr. Thomson was a prolific scientist from a very young age. Over a month, using the analogy with the heat transfer theory of Joseph Fourier, Thomson proposed "The Law of Squares", an initial explanation for why signals sent across undersea cables appeared to be smeared across time, also known as dispersion of the signal, to such an extent that dits and dahs started to overlap, requiring the operator to slow down in order for their message to be readable at the other end and as a result, message speed for the first cable was measured in minutes per word, rather than words per minute. Today we know this phenomenon as intersymbol interference. It wasn't until 1876 that Oliver Heaviside discovered how to counter this phenomenon using loading coils based on his description of what we now call the Heaviside condition where you can, at least mathematically, create a

Foundations of Amateur Radio The first official telegram to pass between two continents was a letter of congratulations from Queen Victoria of the United Kingdom to President of the United States James Buchanan on 16 August 1858. The text is captured in the collection of the US Library of Congress. It's a low resolution image of a photo of a wood engraving. Based on me counting the characters, the text from the Queen to the President is about 650 characters. IEEE reports it as 98 words, where my count gives 103 words or 95 words, depending on how you count the address. Due to a misunderstanding between the operators at either end of the 3,200 km long cable, the message took 16 hours to transmit and 67 minutes to repeat back. If you use the shortest duration, the effective speed is just over one and a half Words Per Minute or WPM. That's not fast in comparison with speeds we use today. Until 2003, the ITU expected that emergency and meteorological messages should not exceed 16 WPM, that a second class operator could achieve 20 WPM and a first class operator could achieve 25 WPM. To put the message speed in context of the era, in 1856, RMS Persia, an iron paddle wheel steamship and at the time, the largest ship in the world, won the so-called "Blue Riband" for the fastest westbound transatlantic voyage between Liverpool and Sandy Hook. The journey took nine days, 16 hours and 16 minutes. Similarly, it wasn't until 1861 that a transcontinental telegraph was established across the United States. In 1841 it took 110 days for the news of the death in office of President William Henry Harrison to reach Los Angeles. Today that distance is covered by a 39 hour drive, a 5 hour flight, and about 12 milliseconds on HF radio. So, while the speed of the message might not be anything to write home about today, at the time it was world changing. Speed in Morse code is measured in a specific way. Based on International Morse code, which is what I'm using throughout this discussion, if you send the word "PARIS" a dozen times in a minute and the next time starts right on the next minute, you officially sent Morse at 12 WPM. Looking inside the message of the word "PARIS", it's made up of a collection of dits and dahs. If a dit is one unit of time, then the letter "a", represented by dit-dah, is six units long when you include the spacing. In total, the word "PARIS", including the space after it, is exactly 50 units long. When you send at 12 WPM, you're effectively sending 600 dit units per minute, or ten units or bits per second, each lasting a tenth of a second. Unfortunately, there is not a one-to-one relationship between Morse speed and ASCII, the American Standard Code for Information Interchange, for a number of reasons. Firstly, Morse is made from symbols with varying lengths, where ASCII, the encoding that we really want to compare speeds with, has symbols with a fixed length. You cannot simply count symbols in both and compare their speeds, since communication speed is about what you send, how fast you send it, and how readable it is at the other end. Thanks to Aiden, AD8GM, who, inspired by my initial investigation, shared the idea and python code to encode Morse dits, dahs and spacing using a one for a dit, one-one-one for a dah, and zeros for spacing. This means that the letter "e" can be represented by "10" and the letter "t" by "1110". You can do this for the standard Morse word "PARIS" and end up with a combination of 50 zeros and ones, or exactly 50 bits. I've been extending the code that Aiden wrote to include other encoding systems. When I have something to show it will be on my GitHub page. However, using Aiden's idea, we gain the ability to directly compare sending Morse bits with ASCII bits, since they share the same zero and one encoding. If you use standard binary encoded ASCII, each letter takes up eight bits and the six characters for the word "PARIS", including the space, will take up 48 bits. Given that I just told you that the Morse version of the same message takes up 50 bits, you could now smile and say, see, ASCII is faster - wait, what? Yes, if you send the word "PARIS " using 8-bit binary coded ASCII it's two bits shorter than if you use Morse. Job done, roll the press, headline reads: "Morse is four percent slower than binary coded ASCII". Not so fast grasshopper. If you recall, American Morse code, the one that has Samuel Morse's name written all over it, was replaced by a different code, made by Friedrich Gerke which in turn was modified to become what we now know as International Morse code. Ask yourself, why did Gerke change the code? It turns out that one of the biggest issues with getting a message across an undersea cable was decoding the message at the other end. Let me give you an example, using American Morse, consider the encoding of "e", dit, and "o", dit-extra-space-dit and now try sending the word "seed" across a noisy line. Did you convey "seed", or was it "sod". In other words,

Foundations of Amateur Radio Morse code is a way for people to send information across long distances. The code we use today, made from dit and dah elements is nothing like the code demonstrated and attributed to Samuel Morse in 1837. Over years and with assistance from Professor of Chemistry Leonard Gail and Physicist Joseph Henry, then Professor of Literature, Samuel Morse, and mechanically minded Alfred Vail developed an electrical telegraph system that automatically moved a paper tape and used an electromagnet to pull a stylus into the paper and a spring to retract it, marking the paper with lines. The original system was only intended to transmit numbers, and combined with a dictionary, the operator could decode the message. The telegraph was able to send zig-zag and straight lines, transmitting the message "Successful experiment with telegraph September 4 1837". The system was enhanced to include letters, making it much more versatile. On the 6th of January 1838, across 4.8 km of wire, strung across a barn, the new design with letters and numbers was demonstrated. To optimise the enhanced version of the code, Alfred Vail went to his local newspaper in Morristown, New Jersey, to count the movable type he found in the compositor's type-cases, and assigned shorter sequences to the most common letters. You might think that this explains the distribution of the codes we see today, but you'd be wrong. The 1838 system used four different element lengths and varied the spacing inside a character. For example, the letter "o" was signified by two dits with a two unit space between them, where today it's represented by three dahs. The letter "p" was signified by five dits, today this represents the number "5", and the code didn't distinguish between "i" and "y", between "g" and "j", and between "s" and "z". A decade later and an ocean away in Germany, writer, journalist, and musician Friedrich Gerke created the Hamburg alphabet, based on the work by Vail and Morse, it standardised the length of the elements and spacing into what we use today, the dit and the dah. He changed about half of the characters and also incorporated four special German characters, the umlaut version of A, O and U and the CH sound - pronounced like the sound for the composer "Bach" or the Dutch name "Benschop" - not to be confused with the CH in child, or the CK in clock, or the SH sound in shop. It was different in other ways. For example, the letter "i" and "j" had the same code. The code was optimised to be more robust across undersea telegraph cables. I'll be coming back to that before we're done exploring, but not today. If you want to skip ahead, the term you're looking for is dispersion. Gerke's code was adopted in 1851 across Germany and Austria and it is known as Continental Morse code. By the time most of Gerke's code was adopted as the European Standard in 1865 as one of many agreements that mark the founding of the International Telegraph Union in Paris, only four sequences of the original 1838 code remained and only two of those, "e" and "h" were identical. Which means that although the idea that Morse code is based around English is often repeated, at this stage it's nothing more than a myth, which my previous word list and subsequent dictionary letter counts across over fifty languages confirm. I'll mention that given Gerke's German heritage, I also made a letter count from a modern German dictionary and one from 1901 and found that the letter distribution in those two are very similar with only the letter "s" and "t" swapped between position four and five in the popularity contest stakes. The German letter Top-5 is "enrts" and the "o" is the 16th most popular letter. Speaking of "o", one observation to make is that the new International Morse code contained the letter "o" as dah-dah-dah, it also contained the letter "p" as dit-dah-dah-dit. These two codes come from an 1849 telegraph code designed by physicist, inventor, engineer and astronomer Carl August von Steinheil. There is evidence suggesting that he invented a print telegraph and matching dot script in 1836, based around positive and negative pulses, rather than pulse duration. I'm purposely skipping over earlier telegraph systems built and used by Carl Friedrich Gauss, Wilhelm Edward Weber, and Steinheil, only because we're talking about Morse code, not the telegraph. The 1865 ITU standard for International Morse code includes several accented letters, symbols for semi-colon, exclamation mark, chevrons and several control codes and both normal and short forms for numbers which merge all the dahs in any digit into a single dah. Many of these codes are not part of the official standard today. I'll point out that over time, experienced telegraph operators learnt to decode dits and dahs based on sound alone, negating the need for paper. This translates directly into how we experience Morse in our hobby today, by tone only. There is a much more detailed explanation on h

Foundations of Amateur Radio Thanks to several high profile races we already know that sending Morse is faster than SMS. Recently I started digging into the underpinnings of Morse code to answer the question, "Can you send Morse faster than binary encoded ASCII?" Both ASCII, the American Standard Code for Information Interchange and Morse are techniques to encode information for electronic transmission. One is built for humans, the other for computers. To answer the question, which is faster, I set out to investigate. I'm using the 2009 ITU or International Telecommunications Union standard Morse for this. Morse is said to be optimised for sending messages in English. In Morse the letter "e", represented by "dit" is the quickest to send, the next is the letter "t", "dah", followed by "i", dit-dit, "a", dit-dah, "n", dah-dit, and "m", dah-dah. The underlying idea is that communication speed is increased by making the most common letter the fastest to send and so-on. Using a computer this is simple to test. I counted the letters of almost 400,000 words of my podcast and discovered that "e" is indeed the most common letter, the letter "t" is next, then "a", "o", and "i". Note that I said "letter". The most common character in my podcast is the "space", which in Morse takes seven dits to send. Also note that the Morse top-5 is "etian", the letter "o" is 14th on the list in terms of speed. In my podcast it's the fourth most popular letter, mind you, my name is "Onno", so you might think that is skewing the data. Not so much. If I use the combined works of Shakespeare, and given that it represents an older and less technical use of language, and doesn't feature my name, I figured it might have a different result. The top-5 in his words are "etoai", the letter "o" is the third most popular, and "space" still leads the charge, by nearly 3 times. I also had access to a listing of 850 job advertisements, yes, still looking, and the character distribution top-5 is "eotin", the letter "o" is the second most popular letter. Because I can, and I'm well, me, I converted the ITU Morse Code standard to text and counted the characters there too. The top-5 letters are "etion", but the full stop is a third more popular than the letter "e", mind you that might be because the people at the ITU still need to learn how to use a computer, seriously, storing documents inside the "Program Files" directory under the ITU_Admin user, what were you thinking? I digress. The "space" is still on top, nearly six times as common as the letter "e". As an aside, it's interesting to note that you cannot actually transmit the ITU Morse standard using standard Morse, since the document contains square brackets, a multiplication symbol, asterisks, a copyright symbol, percent signs, em-dashes, and both opening and closing quotation marks, none of which exist as valid symbols. Back to Morse. The definition has other peculiarities. For example the open parenthesis takes less time to send than the closing one, but you would think that they are equally common, given that they come in pairs. If you look at numbers, "5" takes the least amount to send, "0" the longest. In my podcast text "0" is a third more common than "1" and "9" is the least common. In Shakespeare, "9" is the most common, "8" the least, and in job listings, "0" and "2" go head-to-head, and both are four times as common as the number "7" which is the least common. All this to say that character distribution is clearly not consistent across different texts and Morse is built around more than the popularity of letters of the alphabet. For example, the difference between the left and right parenthesis is a dah at the end. If you know one of the characters, you know the other. The numerical digits follow a logical progression from all dits to all dahs between "0" and "9". In other words, the code appears to be designed with humans in mind. There are other idiosyncrasies. Most of the code builds in sequences, but there are gaps. If you visualise Morse as a tree, the letter "e" has two children, both starting with a dit, one followed by another dit, or dit-dit, the letter "i", and the other, followed by a dah, dit-dah, the letter "a". Similarly, the letter "t", a dah, has two children dah-dit, "n" and dah-dah, "m". This sequence can be built for many definitions, but not all. The letter "o", dah-dah-dah, has no direct children. There's no dah-dah-dah-dit or dah-dah-dah-dah sequence in Morse. The letter "u", dit-dit-dah has one child "f", dit-dit-dah-dit, but the combination dit-dit-dah-dah is not valid Morse. It's those missing combinations that led me to believe that Morse isn't as efficient as it could be and what originally led me to investigate the underpinnings of this language. I think it's fair to conclude at this point that Morse isn't strictly optimised for English, or if it is, a very small subset of the language. It has several eccentricities, not unlike the most popular computer key

Foundations of Amateur Radio If you've ever looked at Morse Code, you might be forgiven if you conclude that it appears to be a less than ideal way of getting information from point A to point B. The idea is simple, based on a set of rules, you translate characters, one at a time, into a series of dits and dahs, each spaced apart according to the separation between each element, each character and each word. The other day I came across a statement that asserted that you could send Morse faster than binary encoded ASCII letters. If you're not sure what that means, there are many different ways to encode information. In Morse, the letter "e" is the first character, represented by "dit", the letter "t" is the second character, represented by "dah". In ASCII, the American Standard Code for Information Interchange, the letter "e" is the 69th character, represented by 100 0101. The letter "t" is number 84 on the list, represented by 101 0100. A couple of things to observe. The order of the characters between Morse and ASCII are not the same. That doesn't really matter, as long as both the sender and receiver agree that they're using the same list. Another thing to notice is that in Morse, letters are encoded using dits and dahs and appropriate spacing. In ASCII, or technically, binary coded ASCII, the letters are encoded using zero and one. I'll also mention that there are plenty of other ways to encode information, EBCDIC or Extended Binary Coded Decimal Interchange Code was defined by IBM for its mainframe and mid-range computers. It's still in use today. In EBCDIC, the letter "e" is 133 and the letter "t" is 163. It was based around punched cards to ensure that hole punches were not too close together. It was designed for global use and can, for example, support Chinese, Japanese, Korean and Greek. Another encoding you might have heard of is UTF-16, which supports over a million different characters including all the emojis in use today. Before I continue, I must make a detour past the ITU or the International Telecommunications Union. The ITU has a standard, called "Recommendation M.1677-1", approved on the 3rd of October 2009, which defines International Morse code. I'm making that point because I'm going to dig deeper into Morse and it helps if we're talking about the same version of Morse. I have talked about many versions of Morse before, so I'll leave that alone, but I will point out a couple of things. The ITU defines 56 unique Morse sequences or characters. The obvious ones are the letters of the alphabet, the digits and several other characters like parentheses, quotes, question mark, full-stop, and comma, including the symbol in the middle of an email address, which it calls the "commercial at symbol" with a footnote telling us that the French General Committee on Terminology approved the term "arobase" in December 2002, but it seems that seven years isn't enough time to convince the ITU to update its own standard, mind you, the rest of the world, well, the English speaking part, calls it "at", the letter "a" with a circle around it, as in my email address, [email protected]. Another thing to note is that this standard is only available in English, Arabic, Chinese, French and Russian, so I'm not sure what the Spanish, Hindi, Portuguese, Bengali and Japanese communities, who represent a similar population size do for their Morse definitions. It's interesting to note that as part of its commitment to multilingualism, the ITU actually defines six official languages. Specifically, the "Spanish" version of the standard appears to be missing. There's other curious things. For example, the standard defines a special character called "accented e", though it doesn't describe which accent, given that there are four variants in French alone, I found at least seven versions and it completely ignores accents on the i, the c, the o, special character combinations like "sz" in German and "ij" in Dutch. This isn't to throw shade on Morse, it's to point out that it's an approximation of a language with odd variations. I'm also going to ignore capitalisation. In Morse there's none and in ASCII, there are definitions for both, capitalised and not. In addition to things you write in a message, there's also control codes. The ITU defines six specific Morse control codes. Things like "Understood", "Wait", and "Error". ASCII has those too. The first 31 codes in ASCII are reserved for controls like "linefeed", "carriage return", and "escape". There are other oddities. The ITU specifies that the control code "Invitation to transmit" is symbolised by dah-dit-dah. If you're familiar with Morse, you'll know that this is the same as the letter "k". The specification says that multiplication is dah-dit-dit-dah, which is the same as "x". There's also rules on how to signify percentages and fractions using dah-dit-dit-dit-dit-dah, the hyphen, as a separator. At this point I haven't even gotten close to exploring efficiency, but my cur

Foundations of Amateur Radio Have you ever made an international contact using amateur radio and used that towards tracking an award like for example the DXCC? If you're not familiar, it's an award for amateurs who make contact with at least 100 "distinct geographic and political entities". In 1935 the American Radio Relay League, or ARRL published an article by Clinton B. DeSoto, W1CBD, titled: "How to Count Countries Worked: A New DX Scoring System". In the article he asks: "Are Tasmania and Australia separate countries?" In case you're wondering, Tasmania has, at least in legal terms, been part of Australia since Federation in 1901. Not to be confused with New Zealand, a separate country over 4,000 kilometres to the east of Australia, Tasmania is the island at the south eastern tip of Australia. It was previously called the Colony of Tasmania, between 1856 and 1901 and before that it was called Van Diemen's Land between 1642 and 1856. Before then it was inhabited by the palawa people who lived there for about 42,000 years. They eventually became isolated after being cut off from the mainland by the Bass Strait when about 10,000 years ago sea levels rose due to the ice age coming to an end. In the last remaining local Aboriginal language 'palawa kani' it appears to have been called 'lutruwita' (/lu-tru-wee-ta/), but no living speakers of any of the original Tasmanian languages exist. As audio evidence, we have a few barely audible sounds spoken by Fanny Cochrane Smith on a wax record from 1899 on which she sang traditional songs. I'm mentioning this to illustrate that DeSoto asking the question: "Are Tasmania and Australia separate countries?" is, in my opinion, fundamentally misguided. More so because of an island, well, rock, Boundary Islet, that's split by a border, one half belonging to Victoria, the other half to Tasmania. Specifically, since 1825, the state of Victoria and the state of Tasmania share a land border thanks to a survey error made in 1801. If you're into Islands on the Air, or IOTA, it's part of the Hogan Island Group which for activation purposes is part of the Furneaux Group, which has IOTA designation OC-195. One point to make is that today the DXCC does not mention Tasmania, either as a separate entity, or as a deleted entity. It was removed from the DXCC in 1947. The DXCC list is pretty famous in amateur radio circles. It's not the only such list. I already mentioned the IOTA list which contains a list of islands and island groups and their IOTA designation. There's also a list of 40 groups of callsign prefixes called CQ zones, published in CQ magazine, and a list of IARU regions maintained by the International Amateur Radio Union. There's also an ITU zone list, maintained by the International Telecommunications Union. Each of these lists are essentially grouped collections with an attached label. The list of DXCC entities is copyrighted by the ARRL. If you want to use it for anything other than personal use you need to ask permission. In other words, if you write software that for example tracks amateur radio contacts and you make that software available for others to use, you officially need permission from the ARRL to use it to track a DXCC. If you're an amateur outside of the United States your peak body will need permission from the ARRL to issue any DXCC award. The ITU, the International Telecommunications Union is a United Nations specialised agency, part of our global community, owned by all humans. It peppers its content with copyright notices. The same is true for the International Amateur Radio Union, the IARU, the global representative body of all radio amateurs. It too peppers its content with copyright notices, even going so far as to add requirements that "(a)ny copy or portion must include a copyright notice" and that "(i)t is used for informational, non-commercial purposes only". Let me ask you a question. Can you achieve a DXCC without international cooperation? Of course not. If you are an American amateur and want to get an award for contacting 100 distinct geographic and political entities, you can only do so by making contacts outside the United States of America. As an Australian however, I have, according to the February 2022 version of the DXCC list, 340 countries to choose from, only one of which is the United States of America, and Alaska isn't part of the United States, apparently. It might appear that I'm singling out the ARRL, but that's not true. CQ Communications, Inc. owns the list of CQ Zones, the ITU owns the list of ITU zones, the IARU owns the list of IARU Regions, Islands On The Air Ltd. and the Radio Society of Great Britain own the IOTA list and Clinton B. DeSoto W1CBD became a silent key in 1949, his copyright expired in 1999. So, is grouping and labelling things sufficient to actually claim copyright? Can I claim copyright for all countries starting with the letter 'A' and calling it the 'Alpha Amateur Award'? My preliminary list for the 'A

Foundations of Amateur Radio In the earlier days of my career I worked in a computing centre at a university surrounded by people with different interests and experiences in computing. There were programmers, hardware engineers, technicians, sales people, administrators, educators, support staff, statisticians and even a librarian. There wasn't a lot of socialising or foosball, but every now and then we'd bump into each other in the lunchroom and talk about things that were not work related. During such conversations I learnt that people had all manner of interests outside their work, they were volunteer firefighters, or building their house, or active in the girl guides and any number of other unrelated pursuits and skills. That same is true for the people inside the hobby of amateur radio. I've met people who were submariners, tow-truck drivers, accountants, paramedics, radio astronomers, telco and broadcast engineers, doctors, IT people, lots of IT people, and plenty of other professions. As you might know, I'm self-employed. I am now acutely aware of mixing business with pleasure because not that long ago, every single time I met another person outside my field I'd get asked about some or other computer problem. Similarly I've witnessed medical professionals being asked about specific and personal medical issues and every time I experienced it or noticed it, a little part of me shied away from either telling people what I did or asking others for professional advice. Now before you think that I'm telling you not to talk about computers within earshot of me, that's not at all what this is about. It's about building an awareness that there are people in your community from all kinds of different backgrounds with different experiences, something which I've talked about many times before, but, and here's a new thing, some of those people do not want to give free professional advice, or be dragged kicking and screaming back into their day-job when they're out having fun. There's a difference between talking about what a virus is and asking about which computer to buy, a difference between talking about the neurological aspects of mushrooms and asking if someone can help you with deciding which medication to use. There's a difference between talking about radio telescopes and asking to access laboratory measuring equipment. If you're unsure where the line is, think of it in this way. If your mate is a plumber, it's one thing asking them what sand in your sink means and another thing entirely to ask them to dig up your backyard. I'm not telling you how to live your life, I'm asking you to be considerate of those around you who might have a skill set that you lack and need, whom you've met through the amateur community. An example of how you might navigate this process is to ask the person if it's appropriate to ask a specific question and to be prepared for hearing "No". Or you might be surprised and find that they're happy to help, to a point. I'd encourage you to be mindful of that point. In case you're wondering, nobody has been stepping on my toes and if you recently asked me a question, you haven't overstepped any lines. At this point you might be wondering what this has to do with amateur radio and why I'm talking about it now. The answer lies in the nature and evolution of our community. If you look at us as we were a century ago, like I did extensively when I discussed the evolving nature of the so-called "Amateur's Code", apparently written in 1923 by Lieut.-Commander Paul. M. Segal, you'll know that the community from last century is nothing like the community today. I'm sure that you agree that today we're not Gentlemanly, we're not beholden to the ARRL, and we're not all male, to name a few obvious changes and as a result the Amateur's code was updated, many times, to reflect our evolution. Those changes came about because people had ideas, had discussions, wrote things down and shared them. That's what this is. A mark on the page saying that I'd like our community to be mindful of the expectations made of the members of the community around us. Where are your boundaries and what did you do when someone stepped on them? I'm Onno VK6FLAB

Foundations of Amateur Radio The other weekend there was an amateur radio contest on. Not surprising if you realise that's true for most weekends. For a change, I knew about this contest before it started, because I missed out a year ago, so I did the smart thing to add it to my diary with an alert a month out. In this particular contest there's points to be made by being a so-called roving station, that is, one that moves around during the contest and in the past that's how I've participated and had lots of fun. So the die was cast and a plan was concocted. Being a rover meant that I would be outfitting my car with my radio. It's been out of the car for several years, taken out when we had the transmission replaced, and never actually returned. I started making lists of everything I'd need, including learning that you can use a bench top power supply to charge a 12V battery if your trusty charger has let the smoke out. I went hunting for the cable that connects the front of the radio to the back and realised that it was still in the car, so I could cross that off my checklist. I decided for the first time that realistically I could log using paper and save myself the heartache of finding a computer with a suitable battery and matching software, especially since I'd be operating with low power so making a gazillion contacts wasn't going to be a problem. I went to the shops to get some road food, in my case I like to bring water and oatmeal bars which keep me going through the night. One change was that the contest only ran for 24 hours, leaving less time for sleep. I found my portable antenna tuner, plugged everything in, configured the radio for remote tuning, and tested it all on the bench in my shack. In further preparation I packed my food, got a headlamp out, spare batteries, a pen and a spare, a ring binder for logging and my wristwatch to keep track of logging times. The day before the contest I parked the car in the sun, extracted all the cables from behind the backseat, installed the radio, the battery, the head, the suction mount, the microphone, the speaker, the antenna tuner and antenna mount, and got everything where I wanted it. In between rain showers I located the ropes I use to keep the antenna from breaking off the car when I'm driving, set it all up to length after hunting through the garage to find my multi-tap antenna to suit. Strapped that all together to the handhold in the cabin with a Velcro strap and called it a day. The next morning I drove to my first activation location, installed the antenna on the 40m band, turned on the radio, tuned it, and called CQ Contest. Made my first contact about six minutes after I started. I was excited. Drove to the next location, made the next contact six minutes later. On a roll I drove to my third spot, where things came unstuck. I spent the next two hours getting nothing. I changed both location and band, setting the antenna to 15m and after initially tuning once I couldn't get it to tune again. I spent an hour trying. Given that I wasn't far from home, I went back for a break and to pick up one piece of equipment that I should have packed when I started, my antenna analyser. I tested the antenna and for reasons I still don't understand, it was only resonant on 19 MHz, not much good if you're trying to tune somewhere on 21 MHz. I moved back to my first spot and changed to the 10m band. Three hours to the minute after my second contact, I made another one, this one outside the state. By this time it had been raining steadily for four hours, despite a forecast of little or no rain. The car was stuffy, no way to open the window and stay dry, no contacts, no fun. I asked myself why I was doing this and decided that I'd learnt a valuable lesson and packed up and went home. I did go out later in the afternoon to provide some moral support to a friend who had made double the three contacts I'd made, but by dusk we had both had enough. My lesson for this week? Test the antenna before you go out and bring your analyser. I must add that I've been contesting for years and I've always packed the analyser but never ever needed it. This time I didn't and Murphy let me know that anything that can happen, will. It might sound like a dejected wet cat story, but I learnt a valuable lesson and now I've got another challenge, to discover just why my trusty antenna stopped working. If I do find out I'll let you know. What unexpected lessons have you learnt of late? I'm Onno VK6FLAB

Foundations of Amateur Radio During the week, prompted by a protest on popular social media site Reddit, I rediscovered that there are other places to spend time. It sounds absurd now, but until then much of my social interaction with the world was via a single online presence. This didn't happen overnight. Over the years more and more of my time was spent on Reddit engaging with other humans around topics of my interest, amateur radio being one of them. As you might know, I'm the host of a weekly net, F-troop. It's an on-air radio discussion for new and returning amateurs that's been running since 2011 and you can join in every Saturday for an hour at midnight UTC. In addition to the net, there's an online component. It captures items of interest shared during the on-air conversation. It's intended to stop the need to read out web addresses on-air, create a historic record of the things we talk about and allow people who are not yet amateurs to explore the kinds of things that capture our interest. Since 2014, F-troop online was a website that I maintained. After the announced demise of the service in 2020 I explored dozens of alternatives and landed on the idea to move to Reddit, which happened in March of 2021. At the time of selecting Reddit as the successor to the website, I wanted to create a space where anyone could add content and discuss it, rather than rely on a single individual, me, to update the website every time something was mentioned. During the net these days you'll often hear me ask a person to post that on Reddit. This to illustrate, at a small scale, how the F-troop community shares its knowledge with each other and the wider community. With the realisation that there are other places to spend time, comes an uneasy feeling about how we build our online communities, and how resilient they really are. Before the Internet our amateur radio community talked on-air, or in person at club meetings, or shared their interests in a magazine, or wrote letters. Today we congregate online in many different communities. If one of those fails or loses favour, finding those people elsewhere can be challenging, especially if those communities prefer anonymity. For quite some time now I have been thinking about how to build a radio amateur specific online community. The issues to surface, address and overcome are wide and varied. I created a list ... hands up if you're surprised ... I will point out that I'm sure it's incomplete, your additions and comments are welcome. Funding is the first item to consider. All of this costs time and money. Amateurs are notorious for their deep pockets and short arms, but they're no different from much of humanity. If this community needs to endure, it needs to be financially sustainable from the outset. Authentication and Identity is the next priority. If it's for amateurs, how do you verify and enforce that and what happens if an amateur decides not to renew their callsign, do they stop being an amateur? Should this community be anonymous or not? Moderation and Content is next on the list. What types of content are "permitted"? What is the process to regulate and enforce it? Is this forum public and accessible via a search engine, or private? Can people who are not yet amateurs benefit from the community and use it to learn? How do you set rules of conduct and how do you update them? How do you deal with rule infractions and how do you scale that? Who is this for? Is it decentralised across each callsign prefix, across a DXCC entity, or based on some other selection criteria? Can you have more than one account, or only one per person, or one per callsign? What about machine accounts, like a local beacon, repeater, solar battery, radio link, propagation skimmer or other equipment? What about bots and APIs? If that doesn't mean anything, a bot, short for robot, is a piece of software that can do things, like mark content as being Not Safe For Work, or NSFW, or it could enforce rules, or look-up callsigns, or share the latest propagation forecast or check for duplicates, scale an image, convert Morse code, check for malicious links, or anything you might want in an online community. The way a program like a bot, or a mobile client, or a screen reader, or a desktop application talks to the community is using an API, or an Application Programming Interface. Incidentally, the protest at Reddit is about starting to charge for access to the API, something which will immediately affect software developers and eventually the entire Reddit community, even if many don't yet realise this. What about system backups and availability? How seriously are we taking this community? Is there going to be a Service Level Agreement, or are we going to run it on a best-effort basis? How long is it acceptable for your community to be inaccessible? What about content archiving and ageing? Do we keep everything forever, do we have an archive policy? What happens if a topic that's permitted one y

Foundations of Amateur Radio Our hobby has been around for over a century. The Wireless Institute of Australia, or WIA, is the oldest amateur association on the globe, having just marked 113 years since formation. The American Radio Relay League, or ARRL, is four years younger, founded in 1914. I'm mentioning these two associations because they documented their journey through many of the years since foundation. The ARRL has published QST magazine since 1915 and the WIA has published Amateur Radio Magazine since 1933. Before the Internet and the Digital Library of Amateur Radio and Communications, magazines like QST and AR Magazine were some ways of documenting and archiving achievements across our community. If you find my professional biography online, you'll read: Experienced polyglot IT professional, software developer, trouble shooter, researcher, public speaker, educator, writer and publisher, founder and small business owner, podcaster, and licensed radio amateur. It's fair to say that I've done a great many things across the technology arena. I have been writing software since before I was a teenager. At the time we used words like freeware and shareware, we copied lines of BASIC from the pages of the latest computer magazine, or recorded the TV teletext signal to access a programme. I recall typing pages of hexadecimal codes and running the result. Very satisfying to make sprites running across your screen. In the decades since, technology has moved on. I've had a front-row seat to see that evolution happen. I've also witnessed one of the victims of the 1980's computer craze, the fundamental obliteration of its history. Much has been lost, either physically by destruction or disposal of boxes of magazines or the deterioration of audio cassette tapes once used to store software. I hold a Guinness World Record of Endurance Computing, set in 1989 during the Hobby Computer Club days, but you'll not find it anywhere other than a copy of the Dutch World Records that might be somewhere in my garage, or not. The twice-daily magazine we published over the three days of the event, Elephant News, was lost to time. I'm mentioning this because this loss is not limited to the 1980's, it's happening here, today. As our hobby evolves into the software realm, we need to consider just how that legacy continues beyond our own lifetime. For example, we have lost access to the fundamentals of how exactly HAM DRM works, we've lost the source for VK Contest Logger to name another, and the collected designs by so-called antenna guru L.B. Cebik W4RNL (SK) are scattered around the Internet, but as far as I know, none of it is complete. Fortunately we have tools at our disposal to keep our history. As I mentioned, the Digital Library of Amateur Radio and Communications or DLARC is an Internet Archive project to catalogue and store current and historic amateur media. In the 30 weeks since starting in October 2022, it now has 75,000 items and continues to grow under the expert stewardship of Program Manager, Special Collections, Kay, K6KJN. The DLARC is not the only tool at our disposal and documentation isn't the only way we share technology in our hobby. More and more of what we do is based around software. We use programs to process signals, to generate and receive different modes, to create logs, to model antennas, to log propagation, and that list grows daily. One of the most significant changes in software since my childhood is that of the introduction of Open Source Software in 1998. I've spoken about this several times before and I recently pointed at Not1MM as an example of an Open Source contest logger, but that is not the only project available. If you visit GitHub.com and search for "amateur radio", you'll discover over a thousand projects showing a healthy ecosystem of activity from people like Daniel EA4GPZ who shared gr-satellites, a collection of telemetry decoders that support many different amateur satellites. You'll find APRSdroid by Georg D01GL, which allows radio amateurs to view and report locations using the APRS network. There's an Arduino based rotator interface by Anthony K3NG, an advanced ham radio logger called CQRLOG by Petr OK2CQR, a radio modem by Dan KF7IJB, remoteAudio by Tobias DH1TW, and the list goes on. I must also point out that I'm only naming the person behind the repository because as is the whole point of Open Source software, anyone can contribute in different ways. You can make a copy of the source-code and write your own version, a so-called fork, or you can create trouble-tickets to explain a bug or problem, there's ways of contributing fixes and ideas and all of that can be done by anyone anywhere. Many of the projects I've just shared are a combination of years of effort by many different people. And that is the point of this conversation. Amateur Radio is a collaborative affair. We learn and share from the experience of others. We document how we built a schematic, or an antenna

Foundations of Amateur Radio Today I'd like to start with saying thank you to the Wireless Institute of Australia for awarding me the Brenda Edmonds Education Award "in recognition of outstanding service in the education of the Amateur Radio Community and advancement of licensees." It's an unexpected honour and a thrill that leads me to a question about how we recognise the people around us. Over the years I've been a member of around a dozen radio amateur clubs and associations. To my recollection, the only one who has ever said thanks, and in my case, more than once, is the Wireless Institute of Australia. What of the other clubs? What about the clubs you're a member of, or the groups you meet-up, either for lunch or on the local repeater? What about when you go out on a field-day and set-up a barbecue? I look around me and I see activity that goes back more than a century. It's fair to say that every member of the community benefits from that effort. Memes on social media notwithstanding, there is real labour and toil, love and heartbreak, success and failure all around you. What process do you have in place to say thanks? Now before you start handing out participation trophies to everyone who turns up, mind you, they did when others didn't, consider what saying thanks might look like in your community? It could be a special QSL card, or a certificate sent in the mail that someone could hang on their wall. I'm not advocating for sending out monetary awards or trophies, or other such paraphernalia, I'm just asking you to consider who in your group is worthy of a thank you and what that might look like. You should also think about what you're saying thank you about. Is it for output, for the number of laughs, the level of participation, how many new club members were signed up, how many contacts someone made, how much fund raising they achieved, how many radios they fixed or how many nets they hosted, or something else? You can think about who in your community might serve as an example to strive for and name the award after them. It might be someone who is active right now, or it might be someone who has attained mythical status in the stories you tell each other around the campfire during an overnight activity. No matter what you call it, what it's for, how often you award it, what you present and whom you present it to, consider that it's a formal way of saying thank you, from the group to the individual, from all of you to one person in particular. Since starting F-troop, I've now hosted more than 600 weekly nets for new and returning amateurs, a feat which we recently celebrated with a morning breakfast on the local aptly named Wireless Hill, but I couldn't have done it without the local repeater group who maintains the repeater we use. I also couldn't have done it without the countless individuals who join in every week, or who quietly sit on the sidelines making sure that the various nodes scattered around the globe are up and running, or the people who did the catering and logistics for the event. Looking back, for me that event represents a missed opportunity to say thank you, something which I intend to do something about in the near future. So, ask yourself. When was the last time someone in your community received a thank-you for their contribution? I'm Onno VK6FLAB

Foundations of Amateur Radio As you might know I'm in the process of building a cross-platform, open source, contest logger. Right now that project is at the stage where there is a proof of concept that you can use and install as a progressive web app on any web browser. It's intended as a starting point for discussion. Note that this is a long way from the stage where you might want to actually use it for any contest, it's not feature complete and if it breaks you get to keep both parts. It's currently cunningly named "contest-logger". No doubt that will change. I'm collecting suggestions for features using the GitHub issue tracker, which you're welcome to contribute to. Behind the scenes, I'm writing the documentation that describes how I want to actually develop and design this application. What kinds of things are important, what will drive the process, all the planning stuff that sets up the project. Of course I'm doing this whilst writing articles, looking for work and dealing with the health-care fun and games associated with being alive. While my project is nowhere near finished, truth be told, it really needs to start first, I've come across a different tool written by a fellow amateur Michael K6GTE. This tool is written for Linux only in Python and is in Beta release at this point. This means that you can install and run the application and most of the functionality works. The application is called Not1MM. Here's what Michael has to say about his efforts: Not1MM's interface is a blatant ripoff of N1MM. It's NOT N1MM and any problem you have with this software should in no way reflect on their software. If you use Windows you should run away from this and use some other program. I personally don't. While it may be possible to get N1MM working under Wine, I haven't checked, I'd rather not have to jump through the hoops. Currently this exists for my own personal amusement. Something to do in my free time. While I'm not watching TV, Right vs Left political 'News' programs, mind numbing 'Reality' TV etc... Michael goes on to say that: The current state is "BETA". I've used it for a few contests, and was able to work contacts and submit a cabrillo at the end. I'm not a "Contester". So I'll add contests as/if I work them. I'm only one guy, so if you see a bug let me know. I don't do much of any Data or RTTY operating. This is why you don't see RTTY in the list of working contests. The Lord helps those who burn people at the... I mean who help themselves. Feel free to fill in that hole with a pull request. You can find Not1MM on Michael's GitHub repository ready for your testing and experimentation. It's also available as a PyPi package if you're already familiar with Python. In my opinion, one thing that this tool does well is consider how contest logging can be customised for individual contests and likely it will serve as inspiration for how I intend to implement the plugins in my own project. I've also submitted a patch to Not1MM so you can use Docker to install it on your own machine or at least see what the requirements are to make it run in your environment. I'm thrilled to have discovered this tool and hope that it solves some of your contest logging issues on your Linux workstation. What features are you hanging out for in your contest logging adventures? Feel free to share your bug reports and feature requests to either Michael's project, or mine, or both. I'm Onno VK6FLAB

Foundations of Amateur Radio A curious thing happens when you become part of the amateur community, you start to talk like an amateur. This phenomenon isn't specific to being a radio amateur, it happens whenever you join any community. Lead by example, one word at a time, you start to inherit a vocabulary that represents that community. Amateur radio, rife with acronyms and so-called Q-Codes, a standardised set of three-letter codes that start with the letter "Q", does this in spades. If you've been around amateurs for more than 30 seconds, it's likely that you have already heard QSL, QTH and QRM, colloquially short for "Yup", "Home" and "Noise". There's an official meaning if you're keen. You can use the three letters as both a question and an answer, so QSL can mean "Can you acknowledge receipt?" and "I am acknowledging receipt." Similarly, QTH means "What is your position in latitude and longitude (or according to any other indication)?" and QRM means "Is my transmission being interfered with?" In those cases, used either with Morse code or Voice, they can make getting the message across simpler, faster, and more accurate, all important aspects of communication. It's easier to get QTH across to an amateur who doesn't speak English as their first language than it is to ask the whole question. Other letter groups also creep into common language of an amateur. You've likely heard the letters: "XYL", but if you haven't, let me explain. Given that amateur radio is an activity dominated by men, "YL" refers to Young Lady and "XYL", refers to eX-Young Lady, a less than complimentary way of referring to one's wife. I'd like to point out something curious. In Morse code, XYL is sent using: -..- -.-- .-.. It's intended to represent the word WIFE which is sent in Morse code as: .-- .. ..-. . Now, if you know anything about Morse, you'll know that a dit is one unit, a dah is three. Individual elements are spaced by one unit. The space between letters is three units and the space between words is seven units. Armed with that knowledge, XYL takes 39 units and WIFE takes 31 units to send. So, sending the shortcut actually takes longer and it's clear that this choice is not about efficiency. Describing someone as an eX-Young Lady to refer to your Significant Other seems very 1950's to me. In the situation where you are the female amateur operator, the apparently appropriate way to refer to your Significant Other is as Old Man or "OM". Are female operators supposed to refer to themselves as YL or XYL? Really? Sexism aside, this is extremely offensive in a same-sex and gender fluid community. Then there's the symbol "88", apparently meant to refer to "Hugs and Kisses", not something I'd feel comfortable sending to anyone other than my partner who is emphatically not an amateur, let alone the idea that it would be appropriate to send it to any random station or the connotations around males sending such a message to a random female operator. So, given that we now live in the 21st century and we're no longer in 1950, perhaps it's time to consider what language we teach new amateurs. One proposal by Chris M0YNG is to refer to the Operator as "OP" and the Significant Other as "SO". Seems like a good start. I will point out that this conversation was brought to my attention by Andreas DJ3EI who was participating in a Mastodon.radio conversation with Tim N7KOM who started the thread. I think it's a worthwhile thing to discuss such an evolution of our language, it goes to the heart of our community, you are what you say you are, and words matter. So, what words, acronyms and symbols do you use in your amateur community and what are you teaching new amateurs? I'm Onno VK6FLAB

Foundations of Amateur Radio Recently the Australian Space Weather Forecasting Centre issued an alert for a Coronal Mass Ejection or CME expected to impact Earth within 24 to 36 hours. This was presented within the context of seeing the resulting Aurora, but as a user of the HF radio spectrum, I'm subscribed to their email list, not for the pretty pictures, though I would be delighted to actually see them with my mark one eyeball, I'm on the list for the impact on propagation for my hobby. As a good citizen I shared the alert with my community both via email and social media and as a result I received some questions and comments. One question was, "What does this mean?", one comment was "it's not going to impact the United States." My response was to point out that HF propagation and the impact of the Sun is a very deep rabbit hole and encouraged further research by supplying several links, including a very detailed video by Rohde and Schwarz titled "Understanding HF Propagation", very, highly, recommended. Whilst watching that video I discovered that the Solar Flux Index is measured using a receiver tuned to 2800 MHz or 2.8 GHz. Being in the business of having receivers scattered around my shack, I asked myself if I had something that was able to receive on that frequency. My RTL-SDR dongle doesn't cut it without extra hardware, it tops out at 1.75 GHz. However, my PlutoSDR has a standard frequency range that goes up to 3.8 GHz out - of the box - and with some tweaks can make it to 6 GHz, so well and truly within range. Now, before I move on, I should mention that an RTL-SDR is a cheap, as-in $20, USB computer accessory that looks like a thumb-drive and is ostensibly built to receive digital television, or DVB-T signals. I've spoken about this previously. It can be used to receive radio frequencies outside the purpose it was built for. The PlutoSDR, or to give its official name the ADALM-PLUTO, on the other hand, something which I've also spoken about, is a single board Linux computer made by some smart people at Analog Devices, specifically for the purposes of learning and experimentation with receiving and transmitting RF. It comes with all manner of documentation and software and to be honest, I'm a little bit in love with mine. Back to measuring stuff. In this case I'm attempting to measure the power levels of radio frequencies at 2.8 GHz. I know of a simple tool called rtl_power that can measure RF power over time and started investigating if that tool had been hacked to be able to use the PlutoSDR, rather than the RTL-SDR dongle. It might have been, but I've not yet discovered it, however, that in turn led me to several other tools, most of which I'm still investigating. What it does tell me is that I'm not the first person to tread these paths, much has happened and been documented in the analogue sphere, some has been done using digital I/Q data and a transverter, a device that can multiply radio frequencies to make them appear in a different part of the radio spectrum, but I'm not yet sure if anyone has made a Solar Flux Index device out of a PlutoSDR. I recalled a wonderful little tool that I've also talked about before, there's a theme here, I'm sure, but the tool, "csdr", written by Andras HA7ILM, which allows you to do all manner of interesting things to a stream of raw data, specifically RF raw data. It has a function called logpower_cf which Andras describes as "useful for drawing power spectrum graphs", which is precisely what I'm looking for. Armed with that I'm now in the process of building a compiled version using Docker, so I can run csdr on my PlutoSDR and perhaps generate a power spectrum graph for 2.8 GHz. Of course that will now require that I learn how to extract raw data, known as I/Q data from the PlutoSDR command-line, process it through the logpower_cf function, output an image and hopefully show the result as a web-page. At the moment I'm still in the weeds with a Makefile, but that's not unusual. Needless to say that I'm working on it and the result will no doubt turn up on my github page when it's done. In the most innocent terms possible, how hard can it be? One takeaway that really needs to be expressed out loud, even if I've hinted at it. All the bits I've talked about here are things I've already been playing with. It wasn't until I came across a salient piece of information about the Solar Flux Index and how it was measured that all the puzzle pieces came together, the PlutoSDR, csdr, rtl-power, logpower_cf, the SFI and a web-server, that I could even imagine this happening. The point being that even if you have all of the puzzle pieces in your hands, it might still take one missing piece of information for your brain to go "Ah-ha, wow, yes, this makes sense, I can do this." So, keep collecting puzzle pieces, relevant to your own interests and one day you too will get to this point. I'm Onno VK6FLAB

Foundations of Amateur Radio On Thursday the 20th of April, 2023 at 04:17:56 UTC the world was subjected to a rare event, a hybrid solar eclipse. In Perth I experienced a partial eclipse and people lucky enough to be directly in line, places like Ningaloo Reef, Exmouth and Barrow Island, experienced a total eclipse. Timor-Leste had the experience of the peak total eclipse. At the time I went into my shack and refreshed the WSPR or Weak Signal Propagation Reporter beacon map I have open and noticed that my beacon wasn't reported. I sagely nodded my head, that makes sense, no Sun, no propagation and I got on with my life. Last week a fellow amateur, Will VK6UU, asked if anyone had any VK6 specific HF propagation reports to make. Being the data geek that I am, I thought to myself, "Aha! I can do some data analytics on the WSPR dataset that I have." So, the die was cast for a few enjoyable hours of importing 2.4 gigabytes of compressed data into a database and constructing a set of SQL queries to see what I could learn. Before getting stuck in, I spent a few hours thinking about the problem. How could I go about doing this? Propagation information is notoriously fickle. You have to consider the obvious things like the Solar Index and the Geomagnetic Index which vary considerably. Then there's the nature of the various reports themselves. Not everyone has their beacon on all the time, not everyone has their receiver on all the time. Weekends are more popular than weekdays and popularity overall is growing exponentially. The solar cycle is on the way to its peak, so there's that variation to consider and if that's not enough, how should you compare the Signal To Noise ratio between weak and strong beacons? With all that in hand I set about constructing a plan. I created a folder to hold my charts and SQL queries, intent on uploading that to GitHub when the work was done. For my very first test I thought I'd count the number of reports per band in a 24 hour window around the eclipse. I imported all the WSPR records that had a VK6 callsign, either as the transmitter or the receiver, given that I was interested in learning if stations transmitting from VK6 could be heard elsewhere and inversely, could VK6 stations hear any other stations? As my first effort, I created a scatter-plot to get a sense of what kind of numbers I was looking at. The initial result was interesting. Around the eclipse itself there was no propagation. This wasn't unexpected, since that's what I'd seen on the day at the time on my own map. I changed my data to use a cumulative count per band to see if any band was particularly different and then discovered that there was no propagation at all, on any band. That seemed ... odd. So, I had a look at the source data and discovered a gap, which accounted for what my chart was showing. I added a fake record for the eclipse time itself, just so I could see where on the chart this gap was. Turns out that for VK6 stations, the gap is just over five hours, but it's not centred around the eclipse. There's a four hour window before the eclipse and a one hour window after it. Then I started looking at all the reports from across the world. To give you a sense of scale, across April 2023 the dataset has nearly 139 million rows. It's 12 gigabytes in size. By contrast, in March of 2008 when the first reports started, there were just over 93 thousand reports in a 7 megabyte file. Charting this shows exponential growth, hitting a million reports in July of 2009, 10 million reports in January 2016 and 100 million reports in October of 2021. So, the eclipse and global propagation. The results came in and the reports are that there was no propagation, on any band at any point during the just under two hours and 12 minutes before the eclipse and the 38 minutes following it. That ... or the WSPRnet.org database was down during the eclipse. So, unfortunately I cannot tell you what propagation was like during the eclipse, since it appears that those records don't exist. Looks like we'll have to wait until 2031 when we can try this again. We'll all be a little older and wiser by that time and perhaps we can come up with a way to ensure that the global central WSPR data server is running without downtime, scaled to match the growing requirements and paid for by a benevolent organisation with deep pockets. I did start considering making lemonade from my lemons and charting the kinds of down time the WSPR server has, but just looking over the various discussion groups showed that this is going to be painful. On the plus side, I learnt about SUM OVER and LAG functions in SQL, so there's that. I must confess that if we're going to seriously use WSPR as a propagation analysis tool we need to fix these kinds of issues. I have no doubt that running WSPRnet.org is a massive enterprise and that it costs real time and money to make that happen. So, who's up for the challenge and will the real owner of WSPRnet.org please raise the

Foundations of Amateur Radio Over the years I've used the phrase, which I shamelessly stole, that amateur radio is a thousand hobbies in one. I've discussed countless different activities and adventures that all fall under the banner of amateur radio, in one way or another. Since becoming a licensed radio amateur I've had the opportunity to speak with many different amateurs and hear their views on what amateur radio means to them. Based on their responses I've often found myself exploring new aspects of the hobby and discovering new and interesting ways to participate in this community. Recently I put together a list of projects that are currently underway in my shack. I discovered that over time this list has evolved from physical radio activities, like portable activations, building antennas, camping, and going to HAMfests, the amateur radio version of a swap meet, into more computer related things like data analytics, writing software, fixing bugs and learning how the insides of a Software Defined Radio works. That's not to say that I've given up on camping, or any of the other things, just that my priorities have shifted over time as I discover over and over again, just how big this hobby really is. I mention this because one of the recurring observations I encounter is that others are doing the same thing day in and day out. That in and of itself isn't an issue, it's that they begin to describe that they're bored, that they've lost interest, that the hobby is in stagnation, that there's nothing new, that they're frustrated with their progress towards whatever goal they've set themselves. For me, the key motivator in this hobby is learning. Everything else follows from there. That might not be your thing. You might be here for the emergency service aspect, or the hill climbing, the soldering and electronics. It really doesn't matter why you're here at all. What keeps it fresh is trying new things. For example, if you're here for emergencies, have you set up a disaster event simulation in your community, or attempted to set-up your station 100 km from home and make contacts, using just the very basics? If you're into soldering and electronics, have you ever designed your own circuit board, had it manufactured, or even manufactured it yourself, built the project and tested it? What about documenting it and making it available as a project for someone else? If you've climbed all the hills in your state, have you tried doing this across the border, or overseas? What about testing with different antennas, or modes, power levels or logging tools? The point being that it's easy to keep doing the same thing. What's harder, but potentially more rewarding, is to try something new and experience what happens. One thing to keep in mind is that things will go wrong. That's where all the learning happens, so keep at it. So, are you doing the same thing over and over again and expecting a different outcome, or are you excited like a newborn puppy, wagging your tail ready for the next adventure? I'm Onno VK6FLAB

Foundations of Amateur Radio One of the more perplexing things is the nature of radio regulation. If you're a licensed radio amateur, you'll be familiar with this idea, but if you're not it's bewildering and apparently absurd. To explain, let me start with a light bulb that your neighbour put on their back porch. It's bright. It's pointing at your house. Like the apparent radiation from a gazillion suns it lights up the bedroom and sleep is hard to come by. Pretty annoying right? As it happens, radio is a lot like that. If you know physics, it's exactly like that, but I'll ignore that for today. In our modern world we have many different radios that each rely on a specific, let's call it colour, of light. In radio terms this is known as frequencies or radio bands and the entire collection is known as the radio spectrum. You've likely seen this without knowing. Your 2.4 GHz WiFi has an in-built frequency, 2.4 GHz, as does your 5 GHz WiFi. Your FM radio in the car has frequencies as well, 97.7 on the dial indicates 97.7 MHz. If you have an AM radio, 720 AM refers to 720 kHz. Hidden in plain sight is why radio is regulated. Those numbers, 5 GHz, 2.4 GHz, 97.7 MHz and 720 kHz are all radio frequencies, or as I suggested, colours. Now imagine turning on a really bright light in the middle of that. All of a sudden your WiFi, FM and AM are wiped out. It doesn't stop there. As I said, there are many different radios, and sources of radio frequencies. Radio transmissions come from your mobile phone, Bluetooth headset, microwave oven, computer, television, remote control, key-less fob, power supply, car, power meter, solar panel, battery charger, LED light bulb, and the list goes on. Essentially anything electronic has a radio component. Some of these are transmitting unintentionally, like an electric motor or a switch mode power supply. Other things are transmitting on purpose, your microwave oven, your Bluetooth headset and your mobile phone. As I mentioned, they're all sharing the same resource, the radio spectrum. At this point you might ask about the impact of a single transmitter among all that. Well, there are a few phenomena that you should know about. Radio waves don't stop. They keep going. There's no boundary. To illustrate that, I have a tiny beacon, a transmitter, that every two minutes sends out a signal that shows my amateur callsign and location. It uses 10 milliwatts. To give you a sense of scale. A typical incandescent light bulb is about 60 Watts. My transmitter uses sixty thousand times less power. It has been heard 13,455 km away, about a third of the way around the planet. I will point out that different frequencies can be absorbed differently depending on how they're used, but you cannot rely on the idea that any radio frequency stops anywhere. Another phenomenon is a thing called harmonics. Radio waves not only share the same space or spectrum, they're related to each other. Unless you take very specific precautions, a transmission made at 100 MHz, will be heard at 200 MHz, 300 MHz, 400 MHz, 500 MHz and so-on. While each of those transmissions gets progressively weaker, they still exist. Now imagine that someone else is using one of those other frequencies to communicate emergency information. It's like their backyard just got hit with a bright light. To give you a specific example of why this can matter. Consider a radio amateur who uses 7 MHz. This is a licensed amateur radio frequency. Unless that amateur takes specific precautions, the 16th harmonic for 7 MHz is 112 MHz. If that doesn't mean anything to you, it's in the middle of the so-called air-band, frequencies used by aircraft around the planet to talk to each other and the ground. Very bad things could happen if safeguards weren't made. As a result, radio is highly controlled and regulated. I'm not going into the laws or legalese here, given that this is a global phenomenon and the rules in their specifics are different in each country. There's a whole hierarchy of regulation, arrived at by international cooperation and agreement. These regulations are not identical in each country, far from it. Each country has their interpretation of the rules and balances those with its own use of radio. For example WiFi, a very popular use of the radio spectrum, can be bamboozling in the endless variation of something so seemingly simple. Most of this is invisible to most people. You go to the store and buy a WiFi base station and you go on your way. With the advent of online shopping, you can click "buy" on any window, regardless of which country the device comes from. If you're not careful your shiny new device, imported from somewhere is actually illegal in your country and fines and punishment can be severe. If you start digging into this, you'll come across rules that for example say that you cannot change the antenna on a particular device. This is because the transmission power of the hardware is strictly regulated so it doesn't interfere

Foundations of Amateur Radio Several years ago I participated in a local contest. Over a 24 hour period I activated my mobile station in about 30 different locations. On my car, my vertical antenna screwed into a boot-lip mount connected to an antenna tuner or ATU, and my radio. I used rope to guy the antenna, threaded through the rear windows and held tight by closing the car boot. Setting up consisted of parking the car, triggering the ATU to tune the antenna system and calling CQ. Moving to the next location consisted of driving there and setting up again. Although this worked really well, I'm skipping over what I'm interested in exploring today. The phrase "triggering the ATU to tune the antenna system" hides a lot of complexity. It was a surprise to me that there were several locations where the ATU just wouldn't tune. Despite my best efforts I was unable to get the system to a point where the radio was happy. In some cases I tuned off frequency and put up with a poor SWR. In others I physically had to move the car and park somewhere else. In every case it was completely unknown if a particular location was going to be a problem. I recall for example parking in an empty nondescript car-park and having to drive around to find a location where my set-up would work. Afterwards I considered that the car-park was potentially built on top of an iron ore deposit, an old industrial area, or a pipe-line, all of which were a good possibility. The point of this is that an antenna doesn't exist in isolation, it's called a system for a reason. We talk about the theoretical isotropic antenna and add disclaimers about that it cannot physically exist because it's infinitely small. One often overlooked aspect of an isotropic antenna is that it's in free space. Free space is defined as space that contains no electromagnetic or gravitational fields and used as a reference. It's a theoretical place. On Earth there is no such thing, there's a planet under your feet, but even in outer space there are both gravitational and electromagnetic fields that impact on an antenna and its performance. Staying nearer to home, recently we had a discussion about how close two antennas can be together. A suggested rule of thumb was that they need to be at least one banana or 30 cm away from each other. Similarly when we erect a dipole, there's recommendations around needing to have it mounted more than half a wavelength over the ground. Some sources say higher. I'll ask the first obvious question. Is that dipole completely straight? In other words, should the centre be half a wavelength above the ground, or should the ends, and how far should the ends be from their mounts? My point is that every antenna exists within the context of its environment and together it's a system. Some environments help the performance of your antenna system and some don't. Depending on frequency, this might not be the same for any location, or antenna design. To be clear, an antenna system consists of the antenna, the feed line and the clips that hold it, the tuner, the radio and its power supply, the mount and the space around it, the radials, the tower, the pigeon poop on the wire, all of it. Until recently my process to get any antenna to perform in a reasonable manner was to set it up, connect an antenna analyser, scan the appropriate range, tweak the antenna, scan again, rinse and repeat until it arrived at something approaching useful, or until it was good enough. If you recall, I recently added some loading coils to a telescopic antenna to attempt to make it resonant on 10m, so I could connect my Weak Signal Propagation Reporter or WSPR beacon to it directly and leave it running independently from my main station. I used the antenna analyser method, got it to the point where I had an antenna with a nice dip right at the required frequency and then watched it go completely sideways when I mounted the antenna in the window. Having spent several hours getting to that point, I walked away and left it for another day. Today was that day. I again started on the floor of my shack and got nothing but an infinite SWR and no amount of tweaking could fix it. Right until the coax fell out of the SMA connector I was scratching my head. After removing the faulty coax lead, I again tweaked the antenna and instead of using my antenna analyser, I fired up my NanoVNA, a tiny handheld open-hardware Vector Network Analyser or VNA. If you're not familiar, it's a standalone palm sized device with an LCD display and battery which will allow you to test most of your RF equipment. This little box came to me via a generous gift from a fellow amateur. It can repeatedly scan a range of frequencies and report in near real-time what's going on. Instead of waiting a minute after each adjustment, I could wait less than a second and immediately see the effect. This has been a game changer. I could mount the antenna against a metal surface and immediately see what the impact was. I cou

Foundations of Amateur Radio When you start in this hobby one of the most frustrating aspects is that of selecting the right antenna. If you've been around for a while, you'll discover that this continues to be the case, even when you've been licensed longer than I've been alive. In the past I've discussed at length why that is the case, but to recap, consider a dipole antenna. In essence it's two pieces of wire that are connected to the radio via some form of feed-line. Now consider the idea of changing the length of each wire. You could trim each end in the same way, or you could make one end longer than the other. You could fold the ends at an angle, or you could mount the dipole near the ground, or high up in the trees, you could position it vertically, or arrange the wires at an angle towards each other. You could make the wire thicker, or thinner, from different material or arrange the ends so they meet up in a circle, or a square, a triangle or some other shape. You get the point, there is endless variation arranging this single antenna and I've not even discussed things like feed-lines, traps, chokes, counterpoise and other RF shenanigans. With that in mind, amateurs around the world are attempting to improve their antenna system every time they get on air to make noise. Recently I reported that my 10 mW WSPR, or Weak Signal Propagation Reporter beacon was heard 13,455 km away in Sweden by Mats SM3LNM on the 10m band. The signal report was -25 dB, which means that with an experimental cut-off for a successful decode at -34 dB, I have 9 dB to play with, so at least theoretically, I could reduce my power even further, to 1 dBm, or just over 1 mW and still make the distance. The antenna I'm using is one built by Walter VK6BCP (SK). It's a 40m vertical antenna, helically wound on a fibreglass blank and clamped to the side of a metal pergola. The antenna is tuned to the 10m band using an SGC SG-237 antenna coupler, essentially a device that can add or remove inductance or capacitance to make my antenna appear resonant on the appropriate frequency. The antenna coupler in turn is attached to about 20 or 30 meters of 75 Ohm, quad shield RG6 which I have left over from my remote internet satellite dish installation days. That's all to say that the antenna system for my beacon is sub-optimal and it's likely that my actual power output is lower than the 10 mW that my beacon is reporting. So, with all that in mind, what else could I try? I have an indoor telescopic antenna stuck to the window and I've been wondering if I can attach my beacon to it directly and leave it running without the need to worry about disconnecting the beacon when I'm wanting to fire up my actual station to make other noises on air. A quick scan with the analyser reveals that the lowest frequency out of the box is about 60 MHz. I decided that adding some loading coils might help, so I set about fabricobbling an antenna, yes, you heard me, fabricobbling, fabricating and cobbling together. Anyway, using 7mm thick drip irrigation riser poly pipe as a form I wound two coils with 1.25mm copper wire that I had lying around. Depending on which calculator you used, that was either too much or not enough for my needs. I managed 53 windings, shy of the planned 60, but still a good start. Using the same irrigation riser, which as luck would have it managed to match the thread for the telescopic antenna elements and feed point, I separated each element by about 100 mm from the feed point, then used the two loading coils to connect the feed point back to each element. An hour later I now have a telescopic antenna, with two loading coils and as luck would have it, I'm much closer. The resonant point is now 30 MHz, down from 60 MHz, so I have a little more tinkering ahead of me. I might change the wire and use some eyelets at the ends to make assembly simpler, but the general idea seems to work as intended. If it doesn't work, I've come across a design for a 25.5 meter long End Fed Half Wave antenna that will work on anything between 80m and 10m and it appears that my driveway is just long enough to fit, but that will negate the indoor aspect of the antenna. All this reminds me of the ugliest dipole I ever saw, in a bush shack, a decade ago, consisting of two wires, haphazardly soldered onto a piece of coax, looped around an insulator, with a piece of wire holding it together, tied between two trees. It was only ever meant to be temporary, but it was there for years. I used it to speak to stations all over the pacific and in the process learnt a lot about the performance of both my radio and the antenna connected to it. The point being that experimentation in antenna building is what we're all about, even going backwards from multi-band, high gain antenna farms, back to basics and exploration. In case you're wondering, I haven't forgotten about the Hustler 6BTV antennas packed in boxes. They're still very much part of the grand plan, but in light of my

Foundations of Amateur Radio There is a fascination with space that arguably started long before the first time that human spaceflight was proposed by Scottish astronomer William Leitch in 1861. Names like Sputnik, Mercury, Gemini, Apollo and Columbia speak to millions of people and organisations like NASA, SpaceX and Blue Origin, to name a few, continue to feed that obsession. In amateur radio we have our own names, things like ARISS, or Amateur Radio on the International Space Station, or its predecessor SAREX, the Shuttle Amateur Radio Experiment. Today, stories about people making contact with the International Space Station continue to make news. We have school programs where amateur radio ground stations schedule a call to speak with an astronaut in space and we've been launching our own amateur satellites for a long time. Launched on the 12th of December 1961, OSCAR1, or Orbiting Satellites Carrying Amateur Radio was built by a group of California based amateur radio operators for 63 dollars. It operated for nearly 20 days, transmitting "Hi" in Morse on 144.983 MHz. The first amateur radio space voice contact was made on the 1st of December 1983, almost forty years ago. It's surprising that in the age of technology such a significant event has been so poorly recorded for posterity. If you go searching for the actual audio, you'll discover several versions of this contact including varying transcripts. I've attempted to reconstruct the wording, but I've yet to hear a complete and unedited version. For example, there's an ARRL movie called "Amateur Radio's Newest Frontier" with out of sync audio. There's also an audio file with a transcript from an archived copy of a website by W7APD. The most recent one is on a video called "HAM - Official Documentary 2022", produced by students from the School of Visual and Media Arts program at the University of Montana and broadcast on Montana PBS on November 24th, 2022. So, what follows is not necessarily complete, but calling from Space Shuttle Columbia it went a little like this: "..U.S. west coast and calling CQ. Calling CQ North America. This is W5LFL in Columbia. In another 30 seconds I'll be standing by. Our spacecraft is in a rotation at the moment and we're just now getting the antenna pointed down somewhat more toward the Earth. So I should be able to pick up your signals a little bit better in the next few minutes. So W5LFL in Columbia is calling CQ and standing by. Go ahead." "This is W5LFL in Colombia, W5LFL in Columbia, orbiting the Earth at an altitude of 135 Nautical Miles. Passing over the US West Coast and calling CQ. So W5LFL in Columbia is calling CQ and, ah, standing by. Go ahead." "W5LFL on STS-9, WA1JXN, WA1 Japan X-Ray Norway, WA1JXN, Frenchtown Montana, WA1JXN standing by." "Hello W1JXN, WA1 Juliet X-Ray November, this is W5LFL, I picked up your signals fairly weakly. I think our attitude is not really the best as yet, but you're our first contact from orbit. WA1 Juliet X-Ray November. How do you read? Over." On board STS-9, Space Shuttle Columbia, was Dr Owen Garriott, W5LFL, now silent key. On the ground was Lance Collister, then WA1JXN, now W7GJ. NASA published an Educational Brief for the Classroom that described Owen's set-up as a battery powered 5 Watt FM transceiver feeding a split-ring on a printed circuit board antenna that will be placed in the upper crew compartment window on the aft flight deck. Others reported that the radio was a Motorola handheld. Logging was done with a tape recorder velcroed to the transceiver. Owen describes the antenna as a "well-designed, hand-held antenna, known as a 'cavity antenna', which could be velcroed to the window. It was about 24 inches in diameter and looked somewhat like a large aluminum (sic) cake pan" There's an edited version of a similarly titled ARRL video called "Amateur Radio's Newest Frontier - ARRL documentary featuring Owen Garriot, W5LFL, on STS-9" showing the antenna as a copper tube, bent into a circle, mounted inside an open aluminium box that was hinged on the window to face outwards. The NASA brief also described a range of frequencies and designated 145.55 MHz as the primary frequency over the United States. It included a whole section about synchronising clocks using WWV in Fort Collins, Colorado, odd and even minute transmission schedules and descriptions on how this should work. Operating during time off, when the antenna was facing Earth, and being on air for about four hours during the mission, around 300 contacts were made across the globe. Today we continue to experiment in space. The callsign N1SS is heard on-air regularly from the International Space Station, astronauts are often licensed radio amateurs, there's a permanent repeater on the ISS, we launch research spacecraft called nano-satellites or more popularly CubeSats for amateur radio at every opportunity. So far there's over 160 satellites and the adventure continues. Speaking of experiments, albeit earthbound

Foundations of Amateur Radio So, I have a confession to make. I'm a contester. I'm not ashamed of this. While I'm in a confessing mood, I'll also mention that I've not participated in many contests in the past few years. This is not for the want of desire, but for the lack of motivation to fix things in my shack that are fundamentally broken. On the weekend I participated in a local contest. I took part for six hours, got on-air and made noise, made about 30 contacts, had a ball. I wasn't playing to win, though I did use the opportunity to refresh and hone some of my rusty skills. The next day I spent much too long converting my log into something that the contest organiser asked for. I also discovered that there was a duplicate entry in my log, not something which I'd expect with only so few contacts, but a reflection on the tool I was using to create my log. I started writing down what I learnt from the experience, operating from my own shack, documenting what worked and what didn't. I commented on several things relevant to me, but to give you a flavour, my operator position is terrible because I'm logging on my main computer and the radio is side-on when I'm facing the computer. The sun was shining directly into my eyes when facing the computer. Holding a microphone I didn't have hands-free, I still don't have an auto-keyer to save my voice, my foot pedal didn't work and my data interface was on loan to another amateur. As I said, these things are specific to me. Logging was worse. It didn't quite bring me to tears, but as the contest went on, it became a problem. I started to write down what was wrong with the tool I was using with a view to submitting patches to fix it when I realised that it wasn't actually built as a contesting logging tool, so I stopped and instead started writing a new list, one that describes what a good contesting tool looks like. It builds on a decade of using different tools and participating in contests in all manner of different situations, from special portable event activations, through to the annual top-tier contests run from a purpose built contest station and everything in between. So, what does the ideal contesting tool look like, for me? It needs to be cross platform, as-in, I should be able to use it on whatever computer I have access to, my Linux workstation, a Macintosh Laptop, an Android phone or tablet and while I'm at it, Windows and iOS and I think it should be able to run on a Raspberry Pi. In other words, there shouldn't be a situation where you cannot run the tool because you have some random combination of operating system or CPU that the developer doesn't support. It must be open source. By that I mean, the code should be available to the entire community. There are too many stories of great tools dying or being held hostage by individuals or small groups. The tool should continue to exist and be usable regardless of the participation of the original developer. Users should be able to fix things, add functionality, change themes, whatever. You should be able to customise it because not every contest needs the same information. For example, the John Moyle Memorial Field Day, a contest run every year during March in Australia requires that VHF and UHF contacts record the maidenhead locator, a four or six character message that designates the location of the station. This is used to calculate distance between two stations and award points accordingly. Such a requirement isn't needed in most other contests. Some contests are considered friendly contests, like the Remembrance Day contest in August. It's common to exchange your name, details about your station and have a chat. You'd be unpopular if you used that approach for the Oceania DX, the CQ World Wide or the CQ WPX contests. In other words, some fields are expected for some contests, but not for others. The tool needs to be able to show if a contact is valid by whatever means the rules for a particular contest decide. It needs to automatically log the time, keep track of previous entries and know about the super check partial list to validate partial callsigns. The user needs to be able to use either a keyboard or mouse, or both, to do all the common contesting data entry. No dependency on crazy keyboard shortcuts, no requirement to click the mouse to make an entry, in other words, the tool needs to be able to get out of the way of the contester. I think it needs to have a plug-in system to accommodate different rules and it needs to be able to export data in whatever format the contest organiser expects. You should be able to use it without needing to be connected to the internet during the contest, it should be easy to update and have the ability to keep a station log for all the contacts ever made. It would be great if it could also import existing logs so you can start to consolidate older logs. Having spent quite some time looking for such a tool and failing, I've come to the conclusion that there's

Foundations of Amateur Radio We describe the relationship between the power of a wanted signal and unwanted noise as the signal to noise ratio or SNR. It's often expressed in decibels or dB which makes it possible to represent really big and really small numbers side-by-side, rather than using lots of leading and trailing zeros. For example one million is the same as 60 on a dB scale and one millionth, or 0.000001 is -60. One of the potentially more perplexing ideas in communication is the notion of a negative signal to noise ratio. Before I dig in how that works and how we can still communicate, I should point out that in general for communication to happen, there needs to be a way to distinguish unwanted noise from a desired signal and how that is achieved is where the magic happens. Let's look at a negative SNR, let's say -20 dB. What that means is that the ratio between the wanted signal and the unwanted noise is equivalent to 0.01, said differently, the signal is 100 times weaker than the noise. In other words, all that a negative SNR means is that the ratio between signal and noise is a fraction, as-in, more than zero, but less than one. It's simpler to say the SNR is -30 dB than saying the noise is 1000 times stronger than the signal. Numbers like this are not unusual. The Weak Signal Propagation Reporter or WSPR is often described as being able to work with an SNR of -29 dB, which indicates that the signal is about 800 times weaker than the noise. To see how this works behind the scenes, let's start with the idea of bandwidth. On a typical SSB amateur radio, voice takes up about 3000 Hz. For better readability, most radios filter out the lower and upper audio frequencies. For example, my Yaesu FT857d has a frequency response of 400 Hz to 2600 Hz for SSB, effectively keeping 2200 Hz of usable signal. Another way to say this is that the bandwidth of my voice is about 2200 Hz, when I'm using single side band. That bandwidth is how much of the radio spectrum is used to transmit a signal. For comparison, a typical RTTY or radio teletype signal has a bandwidth of about 270 Hz. A typical Morse Code signal is about 100 Hz and a WSPR signal is about 6 Hz. Before I continue, I should point out that the standard for measuring in amateur radio is 2500 Hz. This is significant because when you're comparing wide and narrow signals to each other you'll end up with some interesting results like negative signal to noise ratios. This happens because you can filter out the unwanted noise before you even start to decode the signal. That means that the signal stays the same, but the average noise reduces in comparison to the 2500 Hz standard. This adds up quickly. For a Morse Code signal, it means that turning on your 100 Hz filter, will feel like improving the signal to noise ratio by 14 dB, that's a 25 fold increase in your desired signal. Similarly, filtering the WSPR signal before you start decoding will give you roughly a 26 dB improvement before you even start. But there's more, since I started off with claiming that WSPR can operate with an SNR of -29 dB. I'll note that -29 dB is only one of the many figures quoted. I have described testing the WSPR decoder on my system and it finally failed at about -34 dB. Even with a 26 dB gain from filtering we're still deep into negative territory, so our signal is still much weaker than the noise. There are several phenomena that affect the decoding of a signal. To give you a sense, consider using a limited vocabulary, like say the phonetic alphabet, or a Morse character, the higher the chance of figuring out which letter you meant. This is why it's important that everyone uses the same alphabet and why there's a standard for it. To send a message, WSPR uses an alphabet of four characters, that is, four different tones or symbols. Another is how long you send a symbol. A Morse dit sent at 6 words per minute or WPM lasts two tenths of a second, but sent at 25 WPM lasts less than 5 hundredth of a second This is why WSPR uses two minutes, actually 110.6 seconds, to send 162 bits of data, lasting just under one and a half seconds each. If that's not enough, there's a processing gain. One of the fun things about signal processing is that when you combine two noise signals, they don't reinforce each other, but when you combine two actual signals, they do. Said in another way, signal adds coherently and noise adds incoherently. To explain that, imagine that you have an unknown signal and you pretended that it said VK6FLAB. If you combined the unknown signal with your first guess of VK6FLAB and you were right, the unknown signal would be reinforced by your guess. If it was wrong, it wouldn't. If your vocabulary is small, like say four symbols, you could try each in turn to see what was reinforced and what wasn't. There's plenty more, things like adding error correction so you can detect any potentially incorrect words. Think of it as a human understanding Bravo when the person at th

Foundations of Amateur Radio Our community is full of TLAs, or three letter acronyms. Some of them more useful than others. For example, I can tell you thank you for the QSO, I'm going QRT, QSY to my QTH. Or, thanks for the chat, I'll just shut up and take my bat and ball and go home. Acronyms arise every day and it came as no surprise to spot a new one in the wild the other day, SHF. It was in a serious forum, discussing antennas if I recall, so I didn't blink and looked it up. Super High Frequency. Okay, so, where's that? I'm familiar with VHF and UHF and as radio amateurs we're often found somewhere on HF, that's Very High Frequency, Ultra High Frequency and High Frequency if you're curious. Turns out that the ITU, the International Telecommunications Union has an official list, of course it does. The current ITU "Radio Regulations" is the 2020 edition. It's great bedtime reading. Volume one of four, Chapter one of ten, Article two of three, Section one of three, Provision 2.1 starts off with these words: "The radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with the following table." When you look at this table you'll discover it starts with band number four and ends with band number twelve, between them covering 3 kHz to 3000 GHz. In position ten you'll see the designation "SHF", covering 3 to 30 GHz, centrimetric waves. A couple of things to note. The list starts at band four. There are of course frequencies below 3 kHz. The list ends at twelve, but there are frequencies above 3000 GHz. You'll also note that I'm not saying 3 Terahertz, since the ITU regulations specify that you shall express frequencies up to 3000 GHz using "gigahertz". Interestingly the same document has a provision for reporting interference where you can report using Terahertz frequencies, so I'm not sure how the ITU deals with such reports. Another thing to note is that this table doesn't actually define what SHF means. It's nowhere in the radio regulations either, I looked. I'm not sure where the words Super High Frequency came from. There is an ITU online database for looking up acronyms and terms. That leads to a document called "Nomenclature of the frequency and wavelength bands used in telecommunications", which also doesn't use "Super High Frequency" anywhere. That said, using the ITU band four, where its definition starts, the VLF band, or Very Low Frequency, followed by LF, Low Frequency, MF, Medium Frequency, the familiar HF or High Frequency, VHF, UHF, then SHF and beyond that, EHF, Extremely High Frequency and THF or Tremendously High Frequency, yes, Tremendously High. There's a report called the "Technical and operational characteristics and applications of the point-to-point fixed service applications operating in the frequency band 275-450 GHz". It introduces the term "THF which stands for tremendously high frequency" but adds the disclaimer that "this terminology is used only within this Report." Seems that there are plenty of documents on the ITU website using that same definition, so I'm guessing that the cat is out of the bag. THF by the way is defined as being for 300 to 3000 GHz frequencies. By the way, the ITU TLA finder exposes that THF stands for Topology Hiding Function. Where's a good acronym when you need it? Speaking of definitions, I came across the definition of a "taboo channel" which according to the ITU is "A channel which coincides with the frequency of the local oscillator in the single super heterodyne receiver which is tuned to an analogue channel." Anyway, we still have a way to go. Below band four, less than 3 kHz, we have ULF or Ultra Low Frequency, SLF, Super Low Frequency and ELF, Extremely Low Frequency, which is defined as band one, between 3 and 30 Hz. Below that, some have suggested TLF, or Tremendously Low Frequency which apparently goes between 1 and 3 Hz with a wavelength between 300,000 down to 100,000 km. Others have suggested that this is an internet meme, but so far it seems to me that it has just as much legitimacy as any of the other wordings, since it appears that the ITU explicitly excludes such definitions, even if internal documents introduce terms from time to time. It did make me wonder, what comes after Tremendously High Frequencies, Red? Turns out, yes, well, infra-red pretty much follows on from Tremendously High Frequencies. If you think that's the end of it, think again. The IEEE, the Institute of Electrical and Electronics Engineers has its own definitions, of course it does. Unfortunately they decided that you need to pay for their standard. It was first issued in 1976 "to remove the confusion". There's an xkcd comic called "Standards", number 927 if you're looking. It goes like this: Situation: There are 14 competing standards. 14?! Ridiculous! We need to develop one universal standard that covers everyone's use cases. Yeah! Soon: Situation: There are 15 competing standards. Anyway,

Foundations of Amateur Radio Last week I went outside. I know, it was a shock to me too. The purpose of this adventure was to test an antenna that has been sitting in my garage for nearly a year. Together with a friend we researched our options and at the end of the process the Hustler 6BTV was the answer to our question. Before the commercial interest police come out of the woodwork, I'll point out that I'm not providing a review, good or bad, of this antenna, it was the antenna I purchased and went to test. Between the two of us we have three of these antennas. I have the idea to use one as a portable station antenna and another as my base station antenna. Glynn VK6PAW intends to use his as a base station antenna. To set the scene. The antennas came in quite large boxes, just over six bananas long, or more than 180 cm. When they arrived I opened my boxes and checked their content, then sealed it all up and put the boxes on a shelf. Last week Glynn proposed that we set one up and see what we could learn from the experience. You know that I love a good spreadsheet, so planning went into overdrive, well, I put together a list of the things we'd need, starting with the antenna and ending with sunscreen to protect my pasty skin from the fusion experiment in the sky. In between were things like an antenna analyser, spare batteries, tools, imperial, since apparently there are still parts of the world that haven't gone beyond barley measurements. I jest, they authorised the use of the metric system in 1866. My list also included a magnetic bowl to capture loose nuts and washers, you get the idea, anything you might need to test an antenna in the field. Our setup was on a rural property where we had lovely shady trees and oodles of space to extend out a 25m radial mat. We tested many different set-ups. I won't go through them all, but to give you an idea of scale, in the time we were there, we recorded forty different antenna frequency scans. The 6BTV antenna is suitable for 80m, 40m, 30m, 20m, 15m and 10m. We tested with and without radials, raised and on the ground and several other installations. We learnt several useful things. For starters, sitting on the ground with radials the antenna measurements line up pretty well with the specifications and with a suitable base mount to protect the plastic base the portable station antenna is usable out of the box. Any variation on this will result in change, sometimes subtle, sometimes less so. For example, we came up with one installation where the SWR never dropped below 3:1. That's with the antenna on the ground without any radials in case you're wondering. Other things we learnt were that manually scanning each band is painful. When we do this again we'll have to come up with a better way of measuring. The aim for my base antenna is to install it on my roof, bolted to a clamp on the side of my metal pergola. This means that we're going to have to do some serious tuning to make this work for us. It might turn out that we'll start with installing the antenna at Glynn's QTH first, but we haven't yet made that decision. Other things I learnt are that I had actually put together the base clamp when I checked the boxes a year ago, so that was a bonus. The magnetic bowl saved our hides once when a spring washer fell into the lawn. The hose-clamps that come with the antenna require a spanner, but there are thumb screw variations of those that I'll likely use for my portable setup. Other things we need to do is learn exactly how the traps work and how adjusting them affects things. In case you're unfamiliar with the concept of a trap, think of it as a radio signal switch that lets signals below a certain resonant frequency pass and blocks signals above that frequency. In other words, a 10m trap resonates just below 28 MHz. It lets frequencies below 28 MHz pass, but blocks those above it, essentially reducing the length of the antenna to the point where the trap is installed. One test we did was to only use the base and the 10m trap. We discovered that this doesn't really work and that the metal above the trap, as-in the rest of the antenna, isn't just for show, even though it's on the blocked side of the 10m trap. Given that I intend to use my base antenna as my main WSPR transmission point, I need to adjust things so the antenna works best on WSPR frequencies. I intend to use a tuner for when I want to work outside those frequencies. One unexpected lesson was that the awning that Glynn attached to his vehicle was an absolutely essential item. I don't think I'll ever go portable again without one. Life changing would be an understatement. I'm investigating if I can fit one to my vehicle. Having had some health issues over the past months I was anxious about going outside and being somewhat active. I paced myself, protected my back, took regular breaks, sat down a lot, drank litres of water and slept like a baby that night. No ill effects, very happy. As a bonus, I even tran

Foundations of Amateur Radio The world is filled with antennas. You'll find them on towers, buildings, cars and on your next door neighbour's roof. They come in an astonishing variety, to the point where you might start thinking that antennas are a fashion accessory that vary with the season and if you start digging through the history books you'll come across designs that dial that variety up to eleven. Possibly the most visible antenna today is the television antenna and when you start noticing them, the more variation you'll discover. Their basic shape consists of a vertical pole, the mast, with a horizontal pole, the boom. Attached to the boom are various different shapes, or elements, that often vary in length according to some pattern. The shape is designed to collect as much electromagnetic radiation from a particular direction, or in the case of a transmitter, focus as much energy as possible into one direction. This focus is called gain. The more focus, the more gain. One of the oldest designs for this kind of antenna, still in use today, is the Yagi-Uda or Yagi antenna. It was invented in 1923 by Shintaro Uda at the Tohoku Imperial University in Japan and popularised to the English speaking world by his boss Hidetsugu Yagi who claimed to be the sole inventor in his Japanese patent application. He went on to file similar patents in Germany and the United States. Gain for a Yagi varies depending on design. Generally more elements means more gain. Sometimes you'll see a Yagi with weird shorter elements along the boom. This is a design to make the antenna work across multiple frequencies. Another way that this can be achieved is by adding traps along an element. They look like a thick stubby tube at some distance along an element. You can have more than one of these to allow for more frequencies. These improvements allow for several Yagi antennas to share elements and boom space, essentially combining several independent antennas into one. It can be tricky to discover in which direction a Yagi is pointing, but essentially the boom indicates the direction and the end with the shortest element is the front. There's another type of antenna that to the casual observer looks similar. It's called a log periodic dipole array, LPDA or log periodic antenna. It was invented in 1952 by John Dunlavy whilst he was contracted to the United States Air Force. He wasn't credited because it was classified as "Secret", later changed to "Restricted". In 1958 Dwight Isbell built a log periodic antenna as an undergraduate student at the University of Illinois at Urbana-Champaign. He was part of a larger team that included Raymond DuHamel, John Dyson and Robert Carrell. Later Paul Mayes developed a variant that improved performance. Before I dig in, I'll also note that this antenna caused all manner of legal issues that are still in force today. The so-called Blonder-Tongue Doctrine states that a patent holder isn't permitted to re-litigate the validity of a patent that has been held invalid previously. It was a result of the University attempting and ultimately failing to protect its patent for the widely copied antenna design. Reading about this is a fascinating discovery in how a single Judge can make a massive impact on law and society. The log periodic antenna is designed in a way that to the uninitiated looks very similar to a Yagi antenna. It's based on the idea that you can design an antenna made up from independent dipoles that are spaced in such a way that they form an antenna where each dipole radiates to take advantage of its neighbours. Generally a log periodic antenna looks like a triangle. Often the elements are on two separate booms, alternating side-to-side, or you'll see a zig-zag structure that causes the antenna signal to alternate side-to-side. One characteristic of an antenna is called bandwidth. It's a measure of how many frequencies it can operate on within the constraints of the antenna. The wider the bandwidth, the more frequencies you can use with the same antenna. A Yagi antenna typically operates within about four percent of the design frequency. If you combine multiple Yagis by adding traps or different length elements, you'll end up with several frequencies, each with a similar range. A log periodic antenna on the other hand is designed to be used across a large range of frequencies. In shortwave broadcasting there are log periodic antennas that operate between 6 and 26 MHz. In more common use today you'll find log periodic antennas used for higher frequencies. It's not unusual to find log periodic antennas that operate between 400 and 4000 MHz. For even more confusion, you can share the boom of a log periodic antenna with a Yagi antenna as is popular in fringe television reception areas. Some other things to note are that for a Yagi most of the elements are passive and only one is generally a driven element, in a log periodic antenna all elements are driven. For a Yagi antenna, more elements

Foundations of Amateur Radio A is for Antenna, the eyes and ears of any amateur station. You'll spend eighty percent of your life attempting to get twenty percent improvement for any antenna you'll ever use. B is for Balun, bringing together the balanced and unbalanced parts of your antenna system. C is for Coax, the versatile conductor that snakes into your station, one roll at a time. D is for Dipole, the standard against which all antennas are measured, simple to make, simple to use and often first in the many antenna experiments you'll embark on in your amateur journey. E is for Electron, source of all things RF, the beginning, middle and end of electromagnetism, the reason you are an amateur. F is for Frequency, the higher you go, the faster it happens. G is for Gain, measured against a baseline, you'll throw increasing amounts of effort at getting more, one decibel at a time. H is for Hertz, Heinrich to his mother, the first person to transmit and receive controlled radio waves in November of 1886 proving that James Clerk Maxwell's theory of electromagnetism was correct. I is for Ionosphere, the complex and ever changing layers that surround Earth which led radio amateurs to discover HF propagation in 1923. J is for JOTA, the Jamboree On The Air where radio amateurs, guides and scouts come together on the third full weekend of October to share global communications. K is for Kerchunk, the sound caused by the local repeater that brings a smile to the operator and a grimace to the listener, created by pushing the talk button and not saying anything. L is for Logging, the only way you'll ever remember who you spoke to and when and the perfect excuse for bragging to your friends after you managed to collect contacts all over the globe. M is for Modulation, adding information to a radio signal by varying the amplitude, frequency, or phase. N is for Net, a social excuse for getting on air and making noise with your friends. O is for Oscillator, making repeating currents or voltages by non-mechanical means. P is for Prefix, the beginning part of an amateur callsign that identifies your country or region of origin. Q is for QRP, the best way to make just enough noise to make yourself heard, low power is the way to go! R is for Resonance, the point where a circuit responds strongly to a particular frequency and less to others, used every time you tune a radio or an antenna or both. S is for Shack, the space you call home, where you live your radio dream. The size of the corner of the kitchen table, the back-seat of your car or a purpose built structure with never enough space, no matter how much you try. T is for Transceiver, a single box that contains both a transmitter and receiver that share a common circuit. U is for UTC, Coordinated Universal Time, the only time zone that radio amateurs should use for any activity that goes beyond their suburb. V is for VFO, the Variable Frequency Oscillator that provides radio amateurs with frequency agility, the means to listen anywhere, any-time. W is for Waterfall, which displays radio signals across multiple frequencies at the same time. X is for XIT, Transmit Incremental Tuning, changing your transmitter frequency whilst listening on the same frequency, helpful when you're trying to break through a DX pile-up. Y is for Yagi, or Yagi-Uda antenna, the most popular directional antenna invented in 1926 by Shintaro Uda at the Tohoku Imperial University in Japan and popularised to the English speaking world by his boss Hidetsugu Yagi. Z is for Zulu, the last word in the phonetic alphabet that every amateur should know and use. 73 is for best regards. Saying goodbye is hard to do, this says so without fanfare and clears your station from the air. I'm Onno VK6FLAB

Foundations of Amateur Radio Getting on air and making noise is a phrase that you've likely heard me repeat often, actually, this will be the 24th time or so. It's an attempt at encouraging you to actually transmit and use the radio spectrum that is available to you. It's a nicer way of saying: Use it or lose it! One of the more frustrating aspects of our hobby is finding other people to interact with. At the beginning of your hobby you have access to all these magic radio frequencies with no idea on how to use them. Often a new amateur will turn on their radio, call CQ a couple of times to see if there's anyone out there, hear nothing and give up. As you get more experience you'll discover that radio frequencies change over time and that some work better at certain times of the day. This is reinforced by others who will talk to you about propagation, the solar cycle and how the ionosphere and its various so-called layers will change and what you can achieve throughout the day, the year and the long term cycle. Armed with all this knowledge you are likely to get to a point where you make noise on a certain band depending on the time of day. For example, experienced amateurs will avoid the 10m band at night because it's a so-called day-time band, in other words, their perception is that you cannot make contact on the 10m band after sunset and for the same reason, it's not suitable for early morning contacts. What if we could test that perception and see if it's true or not? Turns out that we have a perfect dataset to discover what actually happens. If I look at the 10m band WSPR or Weak Signal Propagation Reporter data for the past year, a year that had me using a beacon pretty much 24 hours a day, you'd expect that you could see just which times worked and which ones didn't. Turns out that regardless of time of day, my beacon was heard across every hour of the day. Of course the numbers aren't uniform across the day. The peak is at noon local time, the trough is at 5 am local time, 10% of reports are at noon, about 1.5% at 5 am. In other words, the worst time of day for my beacon to be reported is 5 am in the morning and it's not zero. Interestingly the same isn't true for the signal to noise ratio, a measure of just how weak or strong a signal is in comparison to the local noise at the receiver. If you account for differences in transmitter power, meaning that a stronger transmitter is measured in the same way as a weaker one, the 10m band has the best signal to noise ratio at my location at 9 pm local time and the worst at 4 pm local time. Given that I'm only using the 10m band with my beacon I also looked at the local OF78 grid square across all bands. It shows that reports are not directly related to when the average signal to noise is best. It seems to me that people are transmitting when they think it works best, not when it actually works best and I'll mention that the definition of "best" depends on each user. Note that I haven't yet sat down to discover if there are automatic transmitter and receiver pairs that have been reporting 24/7 across a year on the same band to determine if there is more to learn about the relationship between how often something is reported and what the signal report was at the time. I can say that it's likely that your favourite band is more popular when others think it's popular, not when the conditions are better. Consider for example that there are no local reports on the 12m band at 10am, but there are at 9am and 11am, so, was the band magically unusable the whole year at that time, or did people just not use it? The same is true for 160m. No reports at all before 5pm or after 3am, despite the bands around it having contacts throughout the day. I will point out some things I've ignored. For example, what is a useful contact? Is it measured by distance, by quantity, by uniqueness? Is this choice the same for each band? Is it reasonable to compare a whole year, or should it be by some other time period, like month, season or lunar month? What is the signal to noise ratio for a band that's considered closed? I'm mentioning this because each of those will directly affect what it looks like when you create a chart and it's likely to change what works best for you. So, next time you get on air, try a band that shouldn't work according to your knowledge and see what happens. Perhaps you'll get lucky, make a contact and discover something unexpected. I'm Onno VK6FLAB

Foundations of Amateur Radio The amateur community is nothing if not entertaining. Look at any discussion about a mode like FT8 and you'll discover people who describe it as the dehumanising end of the hobby. In the same thread you'll find an amateur who's been licensed longer than I have been alive who welcomes it using words like revitalising, more active, and the like. If you're not familiar, FT8 is one of many weak signal digital modes that gained popularity over the past years during the most recent solar minimum when long distance HF propagation was challenging. That example discussion was about the visible end of a mode like FT8, but there's an often overlooked all but invisible aspect of these modes that is much more significant, namely the popularisation of signal processing in software. In many ways amateur radio is more about receiving than transmitting. This might not be obvious, but what's the point of transmitting if you cannot receive? Using software to do the listening makes for an interesting evolution that might be hard to grasp if I start digging into the fundamental algorithms that make this happen, instead let me describe a process that is easier to explain. Imagine that there's a piece of software that knows how to decode digital signals. As the user of that decoding software, or decoder, you send audio into one end and callsigns and grid-squares come out the other end. How it does this isn't important right now. We measure the quality of this decoder by how many times it correctly does this, in other words, how many times a correct callsign and grid-square comes out. The decoder can be improved by changing the way that the decoding process works. If the number of correct callsign and grid-squares that come out increases, the quality of the decoder is improved. Now imagine that the decoder spits out the callsign 7N5EC with the grid-square OF78. This particular combination emerged as a WSPR decode on the 10th of December 2022. It was reported by AA7NM as a 100 Watt signal, 14,882 km away on the 40m band. The signal report was -30 dB. If you know where OF78 is, you'll immediately spot a potential problem, if not, I'll help you out, OF78 is located near Perth in Western Australia. It's unlikely that a transmitted callsign in that part of the world starts with anything other than VK6. Mind you, a weather balloon with an odd callsign could theoretically be overhead in that location, but I've not yet heard of a 100 Watt transmitter on 7 MHz that someone hung from a weather balloon. Another problem is that 7N5EC is a callsign that appears to be Japanese. It starts with 7N which is part of the Japanese callsign block, but the next symbol is the number 5 and at least according to the research I was able to do is not actually a currently valid callsign. The prefix 7N4 is allocated to the Kanto region on Honshu island, the largest island in Japan. 7N5 doesn't seem to be valid as a prefix. Ironically, that callsign will now exist on the Internet as soon as this article is published, but that's a whole other problem. Either way, the chances of the combination of the callsign 7N5EC with the grid-square OF78 is unlikely to be correct. It gets even less likely if you consider that the callsign was reported only once in fifteen years and over 500 million WSPR decodes, I checked. That means that if you updated the software to ignore that particular decode, you'd have improved the decoder by removing an incorrect combination. You could keep doing this by checking callsigns against grid-squares and against allocated callsigns and you'd have made a higher quality decoder. Before you start arguing that this isn't fair, it's exactly the same process as the super check partial list does for people operating in a contest. The idea being that if you only recognise known contesting callsigns, you've got a better chance of making contact. Think of it as a way of filtering out potentially incorrect callsigns. It still leaves the operator having the option to ignore the suggested callsigns and listen to what's actually coming in. I realise that this is not how you would realistically improve a digital signal processing decoder, but it's an example of how changing the software can change the quality of a decoder and that was the point of this example. In reality you'd attempt to discover how this decode happened and what caused it to be wrong. If you want to consider a more signal centric example, consider a decoder that starts with a first attempt at making a decode. With a single decode, it can then remove that known signal from the original audio and start another decoding cycle. You can repeat this as many times as you want until you end up with gibberish. Essentially this is an example of how a modern decoder can improve its performance. This is why signal processing in software is so powerful and important and why FT8 and the rest of the digital firmament are here to stay. I should point out for those wonderin

Foundations of Amateur Radio Sometimes you learn mind boggling things about this hobby, often when you least expect it. Recently I discussed having my 20 mW WSPR or Weak Signal Propagation Reporter beacon heard on the other side of the planet, in Denmark, 13,612 km away. That in and of itself is pretty spectacular, but it gets better if you consider just how weak the signal was by the time it got there. In radio communications there is a concept called path loss or path attenuation. Until recently I understood this to mean the things that impede a signal getting from transmitter to receiver. That includes coax and connector losses, refraction across the ionosphere, reflection off the surface of the planet and diffraction around objects. It turns out there is another factor called "Free Space Path Loss" to consider. It's loosely defined as the loss of signal strength between two antennas. The name sort of implies that something happens to the signal in free space, which is odd if you know that in space, radio waves, regardless of frequency, travel without loss and will travel pretty much indefinitely. So what's going on? To get started, think about a dome lawn sprinkler, one of those little round discs that sits on the ground with the hose connected to the side. You turn on the tap and the water sprays in all directions. If you're really close to the sprinkler when the tap is turned on you'll get sopping wet almost immediately, since most of the water will hit you directly. This is particularly fun in the heat of summer on New Years Day in Australia, not so much in the middle of winter on the other side of the globe. If you stand a couple of meters away, you'll still get wet, eventually, but it will take much longer, because most of the water isn't hitting you. If you stand even further away and assuming the water still gets that far, it will take even longer. A small towel and a big towel will both take the same length of time to get wet if they're held at the same distance from the sprinkler, but if you wring them both out, you'll discover that the big towel captured much more water during the same time. In radio communications we can combine these two ideas, the distance and the size of the receiver, to describe free space path loss. The further away from the transmitter you are, the less signal is available to you to capture since much of the signal is not heading in your direction and the bigger your antenna, the more signal you receive. The bigger the antenna, the lower the frequency, which is why you'll discover that free space path loss is dependent on both distance and frequency. To give you an idea of scale, the free space path loss for 28 MHz over 13000 km is about 144 dB. While the name "Free Space Path Loss" implies loss of signal across the path in free space, the loss is not due to distance as such, rather it's caused by how much the signal is spread out in space. Similarly, there isn't more loss because the frequency is increased, it's that less signal is captured by the smaller size or aperture of the antenna required for a higher frequency. So perhaps a better name might be Spherical and Aperture Loss, but then everyone would have to learn how to spell that, so "Free Space Path Loss" it is. I'll point out that this is the minimum theoretical loss, in reality the loss is higher than this, since it also includes all the other parts of the path loss which are things that we can control, like coax and connector loss, and things we can improve by frequency selection, like ionospheric reflection and refraction which depend on solar conditions. The one aspect of path loss that we have no control over is the "Free Space Path Loss", so perhaps that's why we don't talk about it very much. I'll mention that in path loss calculations often antenna gain at the transmitter and receiver are used to reduce any path loss figures. If I have an antenna with 6 dB gain, then that reduces my overall path loss by 6 dB, which is why we spend so much time and effort figuring out what antenna to use when we get on air to make noise. I mentioned that the free space path loss for my beacon between Australia and Denmark was about 144 dB. This means that my 20 milliwatt signal arrived in Denmark as a -131 dBm signal. That might not mean much, but that's the equivalent of about 80 attowatts. If you're not sure how big that is, 1 milliwatt is 1 quadrillion attowatts, a 1 with 15 zeros. Said another way, 1 watt is 1000 milliwatts, 1 milliwatt is 1000 microwatts. 1 microwatt is 1000 nanowatts, 1 nanowatt is 1000 picowatts, 1 picowatt is 1000 femtowatts, 1 femtowatt is 1000 attowatts. It might come as a surprise, but these numbers are not unusual. Don't believe me? When your radio shows an S0 signal on HF, it is defined as -127 dBm, so we deal with tiny numbers like this all the time, we're just not quite aware of it on a daily basis. Remember, my numbers are theoretical only, to give you an idea of scale. In reality everyth

Foundations of Amateur Radio If you've ever been in the market for a new radio, and truth be told, who isn't, you'll find yourself faced with a bewildering array of options varying from obvious to obscure and everything in between. At the obvious end of the scale are things like price, bands and transmit power and at the other end are things like Narrow Spaced Dynamic Range, which you'll find explained by Rob NC0B on his sherweng.com website where he's been publishing receiver test data for many decades. One of the more subtle options you'll need to consider are handheld, mobile or base radio. This is harder than you might think, since radios are increasing in functionality every time you wake up and if you look long enough, you'll discover that they're getting smaller at the same rate. Once upon a time you could just look at the size of a radio and define it as belonging in one or other category, but that's no longer a useful distinction. For example, my PlutoSDR is a tiny device, fits in my pocket, but there's no way I'd consider it a handheld, or even a mobile radio. You might think that a bigger box has more stuff inside, costs more and performs better. For example, the Drake R-4C receiver and companion T-4XC transmitter require external power and were once rated by the ARRL as very good. In reality the Drake R-4C performed terribly in a CW contest, incidentally, that was what caused Rob to start testing radios in 1976. That receiver and transmitter manage to cover 80m, 40m, 20m, 15m and 10m and together weigh in at 14.3 kg. They're considered a base radio. The Yaesu FT-817, runs on batteries, weighs in at just over a kilogram and can be carried with a shoulder strap. It comes as a single device and covers many more bands than the Drake transmitter and receiver do, it would be considered a mobile or even portable radio. Obviously it would be hard to jam a Drake into your car or strap it to your belt, but does that mean that you cannot use an FT-817 as the base radio in your shack? In case you're curious, the slightly beefier brother to the FT-817, the mobile FT-857d, is sitting on my desk as my current base radio. Has been for years. So why do manufacturers continue to make this distinction between handheld, mobile and base radio? One look at the nearest radio catalogue will tell you that it's not based on either performance or price, not even close. You can buy a handheld with more functionality for the same price as a mobile radio and that same is true when you compare a mobile radio to a base radio. Radios vary in price from $20 to $20,000. A cynical person would suggest that pricing is based around extracting the most money from your pocket, but a more charitable explanation might be that physical size dictates things like the number of buttons you can fit on a radio, how many connectors can be accessed before the radio flies off the desk from the weight of the coax hanging off the box, how big is the display and other such limitations. I'm not being glib when I use the word charitable, since much of modern transceiver design revolves around software which can pretty much fit in any box. Using external computers, neither buttons nor a display are needed, leaving external connectors, which if we're being really honest could all fit in a box that would fit in your pocket. At this point you might wonder if handheld, mobile or base has any meaning at all. As I said, in most cases it doesn't. There's really only one place left where this matters, and that's when you have access to strictly limited space and power if you need to put the radio in your pocket or cram it into your car. For your home shack, the distinction is unhelpful for most, if not all, amateurs. Don't believe me? The Yaesu FT-710 currently ranks fourth on Rob's Sherwood Engineering Receiver Test Data List. It's a quarter the size of the top radio and it's sold as a "Base/Portable Transceiver". Yaesu calls it "Compact". It might not fit in the dashboard of my car, but it will fit on the folding table we use during field days. That isn't an exception either. The Elecraft KX3 is the smallest radio on the first page of Rob's Receiver Test Data list. It fits in your pocket. Before you start collecting statistics for each radio, I should point out that the more you know about this hobby, the harder this process becomes, so be careful. That said, if you have a massive list of anything to choose from, a new amateur radio, pet food, car, what to have for dinner, whatever, here's a process that will guarantee a result. It works by eliminating one item at a time until you're left with your preference. To start, grab the first two items on your list and pick the best one between the two. Ignore everything else, just those two items. You're going to fret about the definition of "best", but don't worry, since every time you do this, you'll have a different idea. All you're doing is saying, all things being equal, between these two options, which one d

Foundations of Amateur Radio It's an immersive effort to create an article every week, so much so, that I've only just discovered that I passed the 600 article mark some time ago. I'd open up a bottle of something celebratory if I thought it warranted the effort, but I'd rather talk about amateur radio and what I've learnt since becoming licensed in December of 2010. This hobby, this community, the activity of amateur radio keeps surprising me in unexpected and exciting ways. I know that there is a part of the community that thinks of this as a dying hobby, but with every fibre in my being I know this to be wrong. We explore, test, build and learn at every opportunity. Put any two amateurs in contact with each other, either physically or over the air and you'll soon witness an exchange of ideas, of things that bring joy, hints of the next thing and the next. The inspiration for my writing comes from all manner of places. For example, here's an opinion recently shared by someone on social media: "Basic antenna modeling using software should be included in ham radio licensing exam syllabus if it's not currently." [sic] As opinions go it's one of the tamer ones I've come across, but it's not unique in any sense of the word. I've heard it described bemoaning the missing knowledge of new digital modes or the need to upgrade my license, or the idea that the introductory license should come with a fixed expiry date. You might have heard similar ones, phrased along the lines of a missing attribute that new licensees should be required to learn or know about before they can call themselves amateurs. It's also completely unhelpful. Let me explain why. I'll start with an analogy. When was the last time your driver's license expired because you didn't upgrade it due to new road rules, new vehicle types, new car accessories or speed limits? In case you're confused, the answer is: never. Does amateur radio cause death and mayhem in the community? No. Do cars? So, in the scheme of things, even if amateur radio can be used to help save lives, it's not an activity that's generally considered life threatening. You could argue that radio amateurs could cause life threatening interference, and technically they can. So can any user of any piece of radio equipment, CB radio, mobile phone, Wi-Fi, you name it. Even a half asleep electronics student in their first year of high-school could do this. The skill isn't specific to radio amateurs. So, what is this about, the requirement for antenna modelling, or some other missing skill, and why does our community keep getting flooded with such, frankly, nonsense? In my opinion, it's the same phenomenon that laments the loss of Morse code, the fact that we lost the 11m band, that we're playing with FT8 instead of AM, that we prefer integrated circuits to valves. The world is a flowing feast and amateur radio is along for the ride. Stand still and the world moves on. Should amateur radio licensing change? Absolutely! It should move with the times. It should lower the barrier to entry at every opportunity. It should explore the possible, not the requirements of a select group of people who decry the dumbing down of the hobby and want to pre-load every license exam with things that are absolutely irrelevant to the turning on of a radio and making noise. Will amateurs benefit from knowing that antenna modelling software exists? Sure they will. Just like they'll benefit from knowing about valves and Morse code. That doesn't mean that they should be part of the exam process. I want new amateurs, no, all amateurs to be curious, to ask, to discover, to explore and to want to know stuff, not because it's a requirement to get a license, but because it's beneficial to their amateur journey. Every week I come up with a different way to look at our hobby because this hobby is so divers. I've used the phrase a 1000 hobbies in one. So far I've just scratched the surface, some 600 weeks in. We'll see where we're at when I've held my license for another decade or so. So, have at it. What is missing from the current exam and why should it be included? I'm Onno VK6FLAB

Foundations of Amateur Radio One of the many questions that new amateurs ask is, "When should I get on-air, and on what band?" The often-heard reply is just to get on-air and make some noise. As time goes by, the importance of this seems to fade in favour of using HF prediction tools. Some amateurs never venture beyond that point, relying almost exclusively on technology to determine if they should turn on their radio or not. If you search the internet for "current HF conditions", you'll end up with dozens of sites boldly claiming to provide precisely that information, some even using the label "Real-Time". You'll find instructions from countless self-proclaimed "experts" on how to read propagation conditions from their favourite site. There's even widgets that you can install on your website displaying propagation data per amateur band with helpful labels like "Band Closed" or showing conditions as "Poor", "Fair" or "Good". Some of these widgets even include an embedded time-stamp to prove just how "current" the information is. If that's how you decide to activate your amateur station, like I once did, I have some questions. Where is this information coming from, is it accurate, and when was it last updated? To give you an idea of just how complex this question is, consider visiting two popular websites, solarham.net from Canada and spaceweatherlive.com from Belgium. On their home-pages, you'll find all manner of numbers, charts, photos, events, notifications, alerts, and warnings, each related in some way to HF propagation and the condition of the Sun. Sounds great, excellent resources, job done. Well, no. Let's start simple. Location. Leaving aside where the site's owner is or where the servers are, both potential sources of confusion, consider where you are and where the remote station is that you're trying to contact. Now compare that with the propagation data location. Do you know where the measurements came from and if they're relevant to you? What about data currency? For example, if you can see the Sun, you can count the number of sunspots since that data comes from physically looking at the Sun. Mind you, can someone count the number of sunspots at night? It's not a trick question. The Sun isn't overhead for everyone all the time, and the data from any particular observer will be out of date at night. When was the count updated? Is it still actually current, let alone real-time? Obviously, not everyone uses the same data source either. In case you're wondering, why are we counting by eye in the space age? It turns out that, since Galileo more than 400 years ago, it's the most long-term, reliable way to keep data consistent between observers and instruments, both of which often last only one or a few solar cycles, and it's also cheap! What about equipment changes and failures in data gathering? Geomagnetic activity isn't global; it's measured using a device called a flux-gate magnetometer. Measurements from specific instruments scattered around the globe are combined into the planetary, or Kp index. You'll discover that locations used change over time, and when instruments are down, the numbers are estimated, but you won't see that unless you actually find and explore the source data. It's not just solarham.net and spaceweatherlive.com; it's pretty much every single site that shows any form of HF propagation or space weather information. Even sites based in a specific country, like the Australian Space Weather Service, have many instruments scattered around Australia. If you happen to be near an actual instrument, where "near" is anything less than 500 km away, how do you know if that instrument was actually online when a measurement was made? Even if the instrument near you is working, is the data relevant to the receiving station on the other side of the planet? If you look closely at the sites giving out current HF conditions, you'll discover that most of these don't even tell you where the data comes from, let alone if any of it was estimated to come up with their current reported values or recommendations. If you start searching for historical information, this problem gets bigger. You'll find many sites that claim to have data, but are invariably underfunded, are rife with broken links, out-of-date servers, and moved, deleted, and abandoned pages. If you unearth a dataset, you'll discover that everyone uses a different standard to record their measurements. How do you even know if combined measurements are coming from the right column? Think I'm kidding? There are documents with warnings about different formats, calculations, and dates on which these changed. Aggregating this data is challenging, at best. So, is there a better way? Yup. You're not going to like it. "Get on-air and make noise!" I can hear you groaning from here. It's not all bad. You can run your own beacon to see the conditions at your location. It's what started me down the path of installing a WSPR, or Weak Signal Propagati

Foundations of Amateur Radio In 2016, Daniel EA4GPZ, documented how to discover the weakest signal that could be decoded using several weak signal modes, including WSPR, or Weak Signal Propagation Reporter. This is an interesting question because as you might recall, I've been experimenting with very weak signals coming from my shack. To date, my 20 milliwatts has been heard over 13 thousand kilometres away. When you tune to a weak station you'll often hear both the station or desired signal as well as interference or background noise. The stronger the signal, the less noise you perceive. The weaker the signal, the more noise. You can express the relationship between the power of these two, the signal and the noise, as a ratio. If the power levels are the same, the so-called signal to noise ratio or SNR is 1:1. A higher ratio, like 2:1, indicates that the power of the signal is higher than the noise and a lower ratio, like 1:2 indicates that the signal is lower than the noise. If you express this ratio in decibels, you'll end up with positive numbers where the signal is stronger than the noise and negative numbers where the signal is weaker than the noise and zero when they're the same. If I tell you that the signal report for my WSPR decode from Denmark was -28 dB, it means that the noise was much stronger than the signal. For today I'm going to leave alone just how WSPR can report a negative signal to noise ratio and still successfully decode the signal, even though the signal appears to be buried in the noise. That said, in this experiment, we're trying to learn something else. Using the technique detailed by Daniel, we test using different, known, signal to noise ratios to discover at what point the WSPR decoding process breaks down. This might help me understand if I can reduce my beacon output power even further and still anticipate a good chance of being decoded successfully. To conduct his experiment, Daniel used the then current version of WSJT-X, version 1.7.0-rc1 and I'm using the current version today, 2.6.0-rc5 to repeat those tests. You might ask why I'm not taking Daniel's word for it and just using his findings. The process to decode a WSPR signal is all software and can be improved with better methodologies and algorithms. It's not unreasonable to think that in the years since Daniel's experiments things have changed, hopefully improved. So, how does this work? If you generate and attempt to decode one hundred different files, you can use the number of times that you count your callsign in the decode list as a percentage of success. If all of your files decode properly, the decode percentage is 100%. If only half of them are decoded successfully, it's 50% and so-on. Similarly, if a different callsign, locator or signal power is decoded, you can count those as a percentage of false decodes. This is important because noise coming from the ionosphere can corrupt any signal. I should point out that because we know in advance what the decoded signal should be, since we created the message, we can actually count the ones that don't match what we sent. In the real world it's very hard, if not impossible, to do this, unless each transmitter also starts recording their efforts so data cleaning can be done after the fact. A false decode happens when the software decodes a message and the result is not what was sent. Due to the way that WSPR works, this is not a case of a single character error and as a result the whole message is corrupt, wrong callsign, wrong grid square and wrong power level. Just how prevalent this issue is, has to my knowledge so far not been discussed. Over the past year I've been working with the entire WSPR data set, nearly 5 billion reports, and mapping the data to explore just what's going on behind the scenes. Based on the raw data every single grid square on the planet has been activated. Of course this is not really the case, since there's plenty of parts on Earth where we haven't yet turned on a WSPR beacon. Back to our experiment. Two tools are used, "wsprsim" to generate an audio file and "wsprd" to decode it. Both come with WSJT-X and when you build the application from source, you get them as part of the process. The generator takes several parameters, one of which is the desired signal to noise ratio. If you ask it for a signal to noise ratio of -20 dB, wsprsim will generate the appropriate noise and the desired signal, combine them and build an audio file. You can then use wsprd to decode that file. If you repeat this many times, you end up with some data. How many times? Well, I probably went a little overboard. I generated a set for each SNR reading between 0 and minus 50 dB in 0.01 dB increments and then generated one hundred for each of those. At the point where the process broke down I doubled the resolution further to get a better idea of what was going on. About three quarters of a million tests. It took a while. What did I learn from this? First of all, fal

Foundations of Amateur Radio Have you ever asked yourself a question that turned out to be a rabbit hole so deep you could spend a lifetime exploring and likely never come out the other end? I did. Yesterday. What's a Volt? This came about when I started exploring how to measure the power output of my WSPR or Weak Signal Propagation Reporter beacon. According to the specifications the output level is 23 dBm or 200 milliwatts. If you read the fine print, you'll discover that the power output actually varies a little depending on which band you're on, for my specific transmitter it says that the output on the 10m band is 22 dBm, or 158 mW. That comes with a disclaimer, that there can be some variation on individual transmitters of about 1 dB. So, on 10m, my output could vary between 21 and 23 dBm, or between 125 and 200 mW. With my attenuator connected, the output could be between 12 and 20 mW, and that's assuming that my attenuator is exactly 10 dB, it's not. Measuring anything means to compare it against something else. To give you a physical example. If you look at a tape measure, the distance between the marks is determined in the factory. The machine that prints the lines is configured to make the lines just so. In the factory there will be a specific master tool that determines how far apart the lines are in that factory. That tool is called "the standard". The process of lining up the standard with the machine making the lines is called "calibration". If you build a house on your own with just that tape measure, everything should work out fine, but if you have a mate help you and they bring their own tape measure, from a different factory, their lines might not quite match yours and the fun begins. If you don't believe me, as I've said previously, pull out all the tape measures and rulers around your house and see just how much variation there is. In my house, well, my CNC, there's a standard that came with my micrometer kit. It specifies physically how long 25mm is. I also have a 50mm and a 75mm standard. When I compare the 75mm with the 50mm and 25mm together, they're the same within one hundredth of a millimetre. It's likely that it's better than that, but I'm still learning how to hold a micrometer and not have it overheat and stretch while I'm measuring. Yes, temperature changes the size of things. The point is, in my CNC world, my current standard sits in my micrometer box. At some time in the future I might want to improve on that, but for now it's fine. The standard that I have was at some point calibrated against another standard. That standard was in turn calibrated against another standard and so-on. Eventually you end up with an SI unit of 1 meter as defined by the International System of Units. In case you're wondering, it's defined as the length of the path travelled by light in vacuum during the time interval of one second. One second is defined in terms of the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom. I know right, runs right off the tongue. I can't help myself, that frequency is 9,192,631,770 Hz. Oh, this system is also subject to change. In 2019 four of the seven SI base units were redefined in terms of natural physical constants, rather than relying on a human artefact like the standard kilogram. This is an ongoing process. For example, in 1960, the meter was redefined as a certain number of wavelengths instead of a physical bar in a vault in Paris and there was also not just one bar, there were 30. National Prototype Metre Bar no. 27 made in 1889 was given to the United States and served as the standard for defining all units of lengths in the US between 1893 and 1960 - yes, perhaps surprisingly, the USA is metric, really. One inch used to be defined as "three grains of barley, dry and round, placed end to end lengthwise" but since 1959 is defined as exactly 2.54 centimetres or 0.0254 meters. Back to power output on my beacon transmitter. Assuming for a moment that I had an actual tool available to measure this, I'd still be comparing my tool against another standard. Let's imagine that I could measure the power output of my beacon with an oscilloscope. When the oscilloscope says 1 Volt per division. How do I know that it really is? If you start reading the calibration steps, you'll discover that they state that you need to connect your scope to a reference, another word for standard, and that's if you're lucky. Some documents just wave their hands in the air and say something like "push the auto calibrate button". The Volt is defined as the electric potential between two points of a conducting wire when an electric current of one Ampere dissipates one Watt of power between those points. The Ampere definition involves counting elementary charges moving in a second. It's in the order of a 10 with 19 zeros. Not to mention that there's also a definition of how much an elementary charge is. You get the point, this is a rabbit hole. So, now let's pr

Foundations of Amateur Radio Propagation, the art of getting a radio signal from one side of the globe to the other, is a funny thing. As you might know, I've been experimenting with WSPR or Weak Signal Propagation Reporter and for about a year running a beacon on 10m. Out of the box my beacon uses 200 mW to make itself heard. I couldn't leave well enough alone and I reduced the output power. Currently a 10 dB attenuator is connected to the beacon, reducing output to a notional 20 mW. I say notional, since I haven't actually measured it, yet. With so little power going out to my vertical antenna, a homebrew 40m helical whip, built by Walter VK6BCP (SK), and tuned to 10m with an SG-237, it's interesting to discover what's possible. Last night my signal was heard in Denmark. Picked up by Jorgen OZ7IT, 13,612 km away. That report broke another personal best for me, achieving 680,600 kilometres per Watt. I was stoked! I shared a screen-shot of my report with friends. One friend, Allen VK6XL, asked a very interesting question. "What makes you think it was short path?" Before I go into exploring that question, I need to explain. If I was to fly from Perth to Sydney, the popular way to travel is across the Australian Bight, over Truro, north of Adelaide, clip the northern tip of Victoria, over the Blue Mountains to Sydney. The distance is about 3,284 km. This route is known as the great circle route, more specifically, the short great circle route. It's not the only way to travel. Instead of heading East out of Perth, if I head West, I'd fly out over the Indian Ocean, Africa, the Atlantic Ocean, the Americas, the Pacific Ocean and finally arrive at Sydney. That journey would also follow a great circle route, the long great circle route. It's about 37,000 km long. You might notice that I wasn't very specific with either the path or distance. There's a reason for that. None of the tools I've found actually provide that information, other than to point out that the entire circumference of the planet is about 40,000 km and that it's not uniform since Earth isn't a perfect sphere. You might be asking yourself at this point why I'm spending so much energy worrying about taking the long way around and how that relates to my 20 mW WSPR beacon. In amateur radio we refer to these two travel directions as the short-path and the long-path. Radio signals travel along the curvature of Earth bouncing between the Ionosphere and the surface. How that works exactly is a whole different topic, but for the moment it's fine to imagine a radio signal skipping like a stone on water. As a stone skips a couple of things happen. If the angle at which it hits the water is just right, it will continue on its journey, get the angle wrong and you hear "plop". Every skip is slightly lower than the previous because the stone is losing a little bit of energy. Every time the stone touches the water it creates a splash that ripples out in a circle from the place where the rock hit. These ripples also get weaker as they increase in diameter. Consider what happens if you skip a rock across concrete or sand instead of water and if you really want to geek out, there's also wind resistance on the rock. A complex equivalent dance affects a radio signal when it propagates between two stations. For success, enough radio energy needs to reach the receiver for it to be decoded. For our signal to make it to the other side of the globe it must bounce between the Ionosphere and Earth's surface. Every bounce gets it closer to the destination. Each time it loses a little bit of energy. This loss happens at the Ionosphere, at the surface and in between through the atmosphere. To give you a sense of scale, my signal report from Jorgen in Denmark was -28 dB. It started here in Perth as 13 dB, so we lost 41 dB along the way. We're talking microwatts here. I'll note that I'm avoiding how this is exactly calculated, mainly because I'm still attempting to understand how a WSPR signal report actually works since it's based on a 2,5 kHz audio signal. As I said, enough energy needs to make it to the receiver for any of this to work. There's an assumption that less distance means less energy loss. It's logical. A shorter distance requires less hops and as each hop represents a specific loss, less hops means less loss. But is that really true? There's nothing stopping my beacon signal from taking a different route. Instead of travelling the short-path, it can just as easily head out in the opposite direction. Theoretically at least, my vertical antenna radiates equally in all directions. The long-path is mostly across water between Perth and Denmark. What if hops across the ocean were different than hops across a landmass? Turns out that they are in several ways. For example, there's less energy loss in a refraction across the ocean, how much less exactly is still being hotly debated. Much of the data is empirical at the moment. It gets better. What if I told you that the re

Foundations of Amateur Radio One of the oldest means of electronic messaging is Morse code. Developed by Alfred Vail and Samuel Morse and sent for the first time on the 24th of May 1844, Morse code changed the way we communicate. For nearly a century it was required to become a licensed radio amateur until in 2003, the International Telecommunications Union or ITU left it to the discretion of individual countries to decide if a budding amateur needed to demonstrate their ability to send and receive in Morse. With that decision many thought that the end of Morse code was only a matter of time. They were wrong. Turns out that use and progress of Morse code continues at a surprising rate. Searching for scholarly articles on the subject, you'll discover that it's used, for communication by quadriplegics, for information exchange between IoT or Internet of Things devices, as a way to secure information combining DNA and Morse code, as a method for gesture recognition, as a research tool for psychologists interested in learning methodologies, for training neural nets, for REM sleep research and plenty more. Learning the code is an activity that sparks joy or dread, depending on whom you ask. For me it's been a decade of anticipation with little to show for it. How to learn is a question that prompts as many answers as there are people within earshot and most of those disagree with each other. If you do ask, you'll discover that there are dozens of websites that offer to teach you, podcasts and audio files, bits of paper, buzzers, software and video, images and cheat sheets, the list is endless. You'll also discover two terms, Koch and Farnsworth. Both are intended means of learning. You'll find proponents of both methods wherever you look. You'll also hear from people who learnt the Army way, whatever that means, there's people who were taught not to send before they could properly receive, those who were taught the opposite and everything in between. There's discussion on the topic, heated even, but very little in the way of actual hard data. There's some research. In 1990 the Keller Method from World War 2 was explored. The method involves playing a Morse letter, followed by a gap where the student is expected to write the letter, followed by a voice prompt of the letter. Interesting, were it not for the fact that it looked at nine students and only at their ability to master the alphabet. In 1960, 310 airmen were subjected to 14 tests to determine their ability to learn Morse. No idea what the research outcomes were, since the Journal of Applied Psychology doesn't appear to share their research unless you pay for it. There are reports of actual science behind the Koch method of learning, but I wasn't able to find it, though it's repeated often. It's only with the introduction of computers that actually using this method of learning has become practicable and recently popular. As you might know, I've been attempting to learn Morse code for a while now. I've tried many different things, including Farnsworth, Koch and others. I publish versions of my podcast as Morse code audio only. They're published every week and there are a few people who listen. I also attempted to make stereo audio files with a computer generated voice in one ear and a Morse word in the other, I generated flash cards, I tried learning the code as dits and dahs, but in the end, nothing really worked for me. About a month ago I came across a video on YouTube by Electronic Notes. It contained the Morse alphabet as audio and flashed the letter visually on the screen whilst the audio was playing. There's also a video with numbers and a combination of the two. It gave me the idea for something entirely different to try and in preparing to talk about this, it turns out that there's even research to suggest that I might be on to something. I discovered that in 1994, sixty healthy people were tested to determine if learning Morse code in a rehabilitation setting was best achieved using visual, auditory or a combination of both. The research conclusion was that the combination works best. My idea is a video that shows an individual word whilst Morse code for that word is heard. There's no dits and dahs on the screen, just the word, written in English, and the Morse code for the word. The speed is 25 Words Per Minute, or WPM, and it's played with a side-tone of 600 Hz. Each video is an entire podcast, lasts about 30 minutes, and plays at full speed. I'm already beginning to notice that some words sound like a sound blob in much the same way as when I learnt a new language, so I'm hopeful that this will finally get me on my way. It's early days and the video channel is an experiment, so please comment to share your thoughts on the experience. Who knows, I might have introduced a new way to learn. Now all we need is some research to compare it to other methods, Koch, Keller, Farnsworth and Onno, hi hi. You'll be able to find this article on YouTube too,

Foundations of Amateur Radio Having been able to call myself an amateur for over a decade, it might come as a surprise to you that it wasn't until a couple of weeks ago that I thought about attenuators for the first time. They're a curious tool and once you come across them, you'll never be quite the same. Before I dive in you should know that an amplifier is an active tool that makes things bigger and an attenuator is a passive tool that makes things smaller. To look at, attenuators are diminutive to say the least. The ones I have in my kit look like barrel connectors, a male and female connector and seemingly not much else, but looks can be deceiving and I'll mention that shape isn't universal. The purpose of an attenuator is to reduce the power of an RF signal by a known amount, preferably without distortion or any impedance mismatches. When you go out hunting and gathering, your choice of connector is the first obvious selection, but soon after you'll be asked for a frequency range, an impedance, a power level and an attenuation level, so let's take a look. I have some attenuators with N-type and SMA connectors. There's options for every connector under the sun, so consider what you're using with your gear and remember to think about your measuring equipment connectors as well. In my case my shack is pretty much SMA the whole way, but a friend had some broadcast N-type attenuators and I was unable to resist. The next thing is impedance. In my case 50 Ohm, but there's options for other choices like 75 Ohm for TV based attenuators. The purpose of an attenuator is to reduce power. It does so by converting power into heat and more power handling means more heat. Too much heat and the attenuator starts letting out the magic smoke, so consider how much power your RF source is generating. Putting out 5 Watts? Then make sure that you don't connect a 1 Watt attenuator to that radio. Now for the attenuation level. It's described in dB or decibel. At first the numbers look bewildering, but pretty soon you'll be familiar with how it hangs together. A 3 dB attenuator will halve the signal, so a 10 Watt signal will be reduced to 5 Watts and a 200 mW signal will be reduced to 100 mW. If you have a 6 dB attenuator, it will halve again, so 10 Watts becomes 2.5 Watts and 200 mW becomes 50 mW. A 10 dB attenuator is a little more than 9 dB, so you could try something along the lines of a bit more than half again, but you don't need to. 10 dB attenuation is essentially moving the decimal point. A 10 Watt signal with 10 dB attenuation becomes 1 Watt. A 200 mW signal becomes 20 mW. If you have a 20 dB attenuator, it moves the decimal point two places, 10 Watts becomes 0.1 of a Watt, or 100 mW and 200 mW with 20 dB attenuation becomes 2 mW. You can connect two attenuators together and combine their values by adding them together. For example, combining a 10 dB attenuator with a 3 dB attenuator makes for 13 dB attenuation which moves the decimal point and then halves that. All that's fine and dandy, but what's the point? Well, imagine that you want to measure the actual power output of your radio. If you were to pump the minimum power level of my Yaesu FT-857d into a NanoVNA you'd blow it up, but if you added say 20 dB attenuation, that 5 Watt would become 0.05 Watts or 50 mW which is half the power rating of the NanoVNA. If you're not confident that your radio is actually putting out 5 Watts, you could add 30 dB attenuation and have a safe margin at an expected output of 5 mW. I mentioned that attenuators don't all look like an innocent barrel connector. That's because if you have to attenuate something with higher power levels, you'll need a way to dissipate heat, in much the same way as a dummy load has cooling fins, higher power attenuators can come with cooling fins too. On the inside of this contraption is a simple circuit made from three or four resistors which combine to attenuate your signal. If you're inclined to build your own, there are plenty of online calculators to be found that show how to put an attenuator together. One thing I've skipped over is the frequency range. Most of us are having fun with HF, VHF and UHF, generally below 1 GHz, so most attenuators will be fine, but if you are playing at higher frequencies you should take note of the frequency range specified for the attenuator. While on the subject of frequency range. You can easily measure the actual performance of an attenuator using a NanoVNA. Connect Port 1 to Port 2 through your attenuator and using the magnitude trace you can see just how much attenuation it provides. Be sure to set the intended frequency range and calibrate without the attenuator before measuring. Now that I know about attenuation, I cannot imagine a life without, but to be fair, I was in blissful ignorance for more than a decade, so this might not apply to you, yet, but one day perhaps you'll find yourself thinking about adding some attenuation to your tool kit. I'm Onno VK6FLA

Foundations of Amateur Radio It's common knowledge that power, as in output power, makes your signal heard in more places. If you've followed my adventures you'll also know that I'm a firm believer in low power or QRP operation. It all started when I was told that my shiny new amateur license was rubbish because I was only allowed to use 10 Watts. Seemingly the whole community around me shared that opinion and slogans like "life's too short for QRP" are still commonly heard. As a direct result of that sentiment I decided to explore and document just how much I could actually do with my so-called introductory license, the Australian Foundation License. I've now held it for over a decade and I'm still exploring and writing. One of my first acts of rebellion was to lower my radio output power to its minimum setting of 5 Watts and half legal power was sufficient to prove my point. Although I'm still regularly being encouraged to upgrade, my second act of defiance is to keep my Foundation License until I decide that I need more. I'll let you know if it ever happens. One more well known so-called "fact" about our hobby is that if you use low power you'll really only get anywhere on the higher bands, 2m, 70cm and above. There's plenty of reports of amateurs using a low power handheld radio to talk to the International Space Station and my own satellite internet used 1 Watt to get to geostationary orbit. On HF on the other hand, 5 Watts is as low as you really want to go. Making contacts is a struggle and often frustrating, but when you do, bliss! About a year ago I took delivery of a WSPR beacon. It's capable of transmitting on all my accessible HF bands using 200 mW. Given my antenna situation I've configured it to transmit on the 10m band, 24 hours a day, thunderstorms excepted. When making the purchase decision I had no insight into how my beacon would perform. 200 mW is stretching even my love of low power, but I hooked it up and turned it on and waited. It came as quite a surprise that my beacon was heard over 15 thousand kilometres away, not once, not a couple of times, but regularly. When I came up with my November challenge to see if I could improve on that I made an almost throw away comment about reducing power to see if I could still make the distance. A couple of weeks ago I hooked up a 6 dB attenuator to my beacon, reducing the power from 200 down to 50 mW. It came as quite a surprise that my signal made it to the same receiver in the Canary Islands. My kilometre per Watt calculation shot up, quadrupling my previous record. Just imagine, 50 mW making its way over a third of the way around the globe, bouncing between the ionosphere and the planet, just like any other HF signal. At that point I realised I had learnt a few things. You don't need stupid power to make a distant contact on HF either. I started wondering just how little power was needed to get out of the shack. Yesterday I hooked up a 10 dB attenuator and within ten hours my now 20 mW beacon broke my own kilometre per Watt record again and based on the signal to noise numbers from previous contacts, I see no reason for that record to stand for very long. Once that happens I've got plenty more attenuators to play with and I'm not afraid to use them. Now I'm on the hunt for an attenuator that will reduce my main radio output from 5 Watts. I'm told I should aim for double the power rating, but I also have to consider how to connect my antenna coupler which needs 10 Watts to tune, but that's a project for another day When was the last time that you used really low power? I'm Onno VK6FLAB

Foundations of Amateur Radio Recently I discussed the concept of a VFO, a Variable Frequency Oscillator. It's an essential building block for our amateur radio community. In describing the idea behind it, while making an error in one of the CB radio frequencies, thanks to Ben VK6NCB for picking that up, I skirted around how a VFO actually works. In reality the VFO is a collective term that describes a whole range of different methods to vary a frequency. Naturally I continued my exploration and discovered a whole range of documentation on the subject. I even started writing about how one common method, a Phase Locked Loop or PLL, works and how a VCO, a Voltage Controlled Oscillator, operates as part of that. I'll come back to those shortly. In doing my reading, since, as is often the case, I use my weekly contribution to the world as a method to learn things. I'll investigate a topic and attempt to describe who came up with it, what it means, how it works and what its place is in the world, the who, where, why and what of it, if you like. I suspect that comes from my very first introduction to broadcast radio where that was one of the very first things I was taught, thirty years or so ago. If you've followed along for the decade I've been at this you'll know that I also intersperse such learning with observations about the things that I'm interested in. This is such an observation, a meta view if you will. I discovered somewhat to my chagrin that the ways that an essential component of our hobby, a system called a Phase Locked Loop, was described in such academic terms, complete with formulas and detailed circuits and even component lists, spread over pages and pages of verbiage, or explained in YouTube videos lasting an hour or more. Of course there were some little gems, ElectronicNotes on YouTube manages to cover the basics in little over six minutes, but that's a rare example. It reminded me of a website that I've been using to fill in the gaps in my understanding of SDR or Software Defined Radio and Digital Signal Processing or DSP. The PySDR.org site is an online textbook written by Dr. Marc Lichtman. He says about his method: "Instead of burying ourselves in equations, an abundance of images and animations are used to help convey the concepts [...]" My weekly efforts have always attempted to do exactly that and I found myself in a place where such a thing didn't appear to exist for the concepts behind the PLL and VCO. My obvious response to that would be to write the missing document and as I said, I have a first draft of it sitting on my computer. There's only one problem. I don't yet "grok" the concepts. If you're unfamiliar with what grokking is, it means to understand intuitively and emphatically. It also means that unless I can describe it in less than a single page of A4 paper I don't understand what I'm saying and you'll get bored waiting for me to make a point. Here's my point. How do you learn concepts? What is it that you do to discover new topics of interest and how do you progress through the various stages between discovery and grokking? For me it's about puzzle pieces. It's always been puzzle pieces. Little nuggets of information, almost trivial on their own, but after a while you get to a point where you have enough of them that you can start joining them together to grasp a more complex concept. Here's a puzzle piece I discovered today. Impedance: The difference between an explosion in air and one under water is impedance. It's little concepts like that which make me get out of bed and discover what's on the horizon next. I'm also learning about double and triple conversion superheterodyne radio which I believe has a one-on-one parallel application in Software Defined Radio and Digital Signal Processing. Once I figure out how to describe it to you, I'll let you know. The point of all this is that learning things is as much about understanding as it is about explaining. Feel free to point me at new and interesting basic concepts. I'm Onno VK6FLAB

Foundations of Amateur Radio One of the many acronyms that define the world of amateur radio is VFO. It stands for Variable Frequency Oscillator. That doesn't explain much if you're not familiar with the purpose of it and just how special this aspect of amateur radio is. Much of the world of radio beyond our hobby, like broadcast television, WiFi and Citizen Band or CB, to name a few, uses radio spectrum in a particular way. On a television you change channels to switch between stations. Similarly, a WiFi network uses specific channels to make your wireless network a reality and the same goes for CB, different channels to make yourself heard. Looking specifically at CB for a moment, if you look at channel 8 for example, depending on which type of equipment you have, your radio might be using 27.055 MHz, or 476.575 MHz, or 476.6 MHz. Each of those frequencies can be described as CB channel 8. The first is on the 27 MHz or 11m band, the second is if you're using a 40 channel radio, which is now depreciated and the third is if you're using an 80 channel radio. If you look at digital broadcast television, channel 8 is on 191.5 MHz. On WiFi, channel 8 is on 2.447 GHz or 5.040 GHz. You get the point, depending on where you are as a user of radio spectrum, channel 8 might mean a whole host of different things and as I've described with CB radio, that might even change over time. Harry Potter needed magic to reach Platform Nine and Three-Quarters at Kings Cross Station to get to school. In a channelised world, getting to an in-between frequency is not possible if you're using licensed equipment, unless you're a radio amateur, then you can use magic to get into the gaps. That magic is called the VFO. You might recall that our radios use many different frequencies internally to be able to filter out specifically what signal you want to hear. Most of those frequencies are fixed, in fact in the vast majority of cases these are actually tuned and calibrated to work in a very specific way. The one exception is the VFO, it's by nature variable. It's likely calibrated, but it's not fixed and that allows our community to tune our equipment to any frequency we desire. The traditional user interface for this is a big knob on the front of your radio, colloquially referred to as the dial, as-in turn the dial to change frequency. This allows us something quite rare in radio land. We can be frequency agile. It means that if there's interference at a specific frequency, we can tweak our VFO and slightly modify where our radio is tuned. You use this almost subconsciously when you're on HF trying to tune to a particular station. In the world of software radio there's likely no knob. You type in a number and the variable frequency oscillator in the radio is tuned to another frequency and the output signal, or transmit signal if you're making noise on-air, changes to another frequency. Digital modes like WSPR, which generally use a very specific frequency also vary that frequency but in a different way. You set your radio to the appropriate so-called dial frequency, let's say 28.1246 MHz on the 10m band and then the software alters the signal by up to 200 Hz to change within the available audio range of your radio, altering between a low of 1400 Hz and a high of 1600 Hz, making the actual WSPR frequency on 10m between 28.1260 and 28.1262 MHz. I'm mentioning the WSPR example because while we're frequency agile in our hobby, we do use channels as well. There's a specific set of frequencies set aside, channels if you like, for WSPR, FT8 and other modes. We do the same on the 2m and 70cm bands where we have rules for where repeaters are allowed to be. It means that we get the best of both worlds. We have the stability and institutional knowledge where repeaters or some modes go, but we also get to play in any spot we want. For example, there's nothing stopping me and a friend setting our radio to some random frequency within our license allocation and outside pre-allocated space and run a WSPR transmitter there. Only the two of us will know about it, well at least at first, but it allows us to experiment away from any other users who might experience interference from our tests and exploration. The VFO is what makes our hobby so very interesting and it's what makes it possible to do weird and wonderful experiments. I'm Onno VK6FLAB