Bald Yak 20: More Pi with the Soap

Foundations of Amateur Radio The thing I think I love most about the hobby of amateur radio is the challenges it represents, not in terms of life or emotional ones, though I will admit that there's some of those .. in no small part due to the variety and complexity associated with being human and a member of the community, more in terms of figuring out how stuff works and then how much stuff there is. I was first licensed in 2010 and since then I've attempted to document the experience of being an amateur and discovering just what that might mean. This week has been interesting, if not quite as productive as I was hoping for. I spent a full day working on SoapyAudio, you might recall, it's one of the potential puzzle pieces in my Bald Yak project. I can report that it compiles fine on a Raspberry Pi 2, and when I get a moment I suspect that it will also work just fine on a Pi Zero. When I got to the point of packaging it all up, I spent hours trying to get my head around the Debian packaging system. For reasons I don't understand, nobody appears to have written anything that monitors the standard 'make install' step, save for one project called 'checkinstall' which has some serious bugs, like overwriting the system password file, and is not recommended. While in the middle of that adventure I discovered that SoapySDR and associated modules, utilities and support tools are already packaged in Debian. I'll confess that I emulated a stunned mullet when I noticed that. While this might mean that I essentially spent three days shaving a Yak for apparently no good reason, it did allow me to discover that SoapyAudio is currently receive only, but adding transmit doesn't look like an unsolvable problem. I still don't know why I went down the compilation steps but it allowed me to peruse the source-code which helped discover how some of this hangs together and I'll hasten to add that my understanding is currently incomplete at best, but that's par for the course. After discovering the existing packaging I installed 'soapyremote-server' on the Pi and it worked out of the box .. something which I'm happy to say is a regular occurrence with Debian packages, perhaps this is why packaging is so complex, another thing to investigate as time permits. I then added an external USB sound card with the audio going into the rear DATA socket of my FT-857d, and together with the CT-62 compatible USB CAT cable, that's Computer Assisted Tuning, allowing remote control of the radio, the Pi was ready to be the network interface to my copy of GNU Radio. Well, not quite. There's some secret incantations that I have still to divine, but thanks to random forum posts with hints at how to format the command string required, I'm making progress. GNU Radio can see the Soapy Server, has passed the checks to control the radio, which happens behind the scenes thanks to Hamlib, but stumbles on the audio card side of things. If it weren't for other life affirming activities in my diary, I would be reporting success, but I can tell you that I can taste it. Now, why does this make me excited? Well, it means that I can now use my FT-857d across the room, technically across the Internet even, to receive and process RF within GNU Radio. You might recall that this is one of the stated aims of this whole endeavour. In terms of "50 things to do with an SDR", this one will end up in the "Listen to conversations on the 2-meter amateur radio band" pile. While it's not particularly exciting to listen to the local repeater across the room, something which I can do by turning up the volume or getting a long headphone lead, it represents a small milestone in the pursuit of my Bald Yak project which aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio. It's called Bald Yak because by the time I'm done, the Yak is likely well and truly shaved. So .. micron by micron I'm getting closer. Also, "like a stunned mullet" means to be dazed and uncomprehending, feel free to use it in public. I'm Onno VK6FLAB

Foundations of Amateur Radio Previously I've talked about a piece of software called SoapyAudio. It's part of the toolkit called SoapySDR which in turn is part of a whole ecosystem called the Pothos framework, coordinated by Pothosware, founded by Josh Blum. I'm mentioning this for two reasons, first to give credit to Josh and the many contributions he has made to the Software Defined Radio ecosystem and second, to indicate that there's several moving parts here. SoapyAudio is a module that connects an audio device, like a microphone or a speaker, more on that in a moment, to a tool called SoapySDR. This allows you to connect to that device, either directly, or over the network, from within any Soapy compatible SDR tool, like Cubic SDR, SDRangel, Quisk and SDR++ to name a few. Said differently, you can use the SoapyAudio module to pretend that your sound card is a Software Defined Radio, and use the associated SDR tools to use it. While interesting in and of itself, the idea comes into focus if you consider that you could connect your analogue radio to the sound card and now you have actual radio frequencies coming into your card, which you can use as an SDR. This works because SoapyAudio also includes Hamlib support, which in turn means that you can send commands like: Set the Frequency, or Set the Mode, to your radio using Hamlib, better yet, if you do this within your SDR software, all this happens behind the scenes. Now, before I dig in too much more, I mentioned a microphone and speaker. When you connect your radio to a computer, the microphone or line-in socket is used to receive audio from the radio, it leaves the radio and enters the computer via the microphone and gives you the ability to receive audio, alternatively, when you connect the computer speaker to the radio, it leaves the computer and enters the radio, to transmit audio. Right now I see no evidence that SoapyAudio supports the ability to transmit, and the ecosystem overview shows the module in a different location than the other radio modules. It might well transpire that none of this is going to work long-term, but the point of this is to learn how it works and to get an understanding of how data flows back and forth. Ideally, I'd end up with a module that would integrate into GNU Radio using the existing SoapySDR integration, but I'm nowhere near that, and my ongoing computing challenges keep banging me in the face, so small steps. If you're not quite sure how this is supposed to work, your radio is connected to your computer using audio in and out, as well as a serial or USB connection. The computer is running SoapyAudio which uses Hamlib to control the radio and uses SoapySDR to send and receive both control and radio signals through a tool called soapy-server, which I think will all run on a cheap Raspberry Pi which is in turn is connected to the network to another more beefy computer running GNU Radio and the SoapySDR module, allowing you to both control the radio over the network as well as receive and transmit. Well .. at least that's the plan. In order to bring that grand idea closer to fruition, I've just spent the past two days putting together a set of instructions, in the form of a Dockerfile, to attempt to help make that happen. I'll note upfront that this is a work in progress and there were plenty of trips to the local Yak Shaving compound to sharpen my blades, but I think by now you'll understand that this is par for the course. I'm sharing all this with you because in amateur radio and in any complex endeavour, progress is made by making small incremental improvements. We're up to the 19th, or 20th, if you count the introduction of my Bald Yak series and so far I have only very little tangible assets to show you. I suspect that this is going to be the case for some time to come. Perhaps my journey should be viewed as a way to pursue the things you're interested in and document your progress along the way, rather than a journey towards a product that you can install tomorrow morning after you've had your morning coffee. If all that made your head explode, don't worry, you're in good company. I embarrassed myself in front of all the HamSci community the other day when I proposed to use a spectrogram to capture and understand Ionosonde data, rather than raw IQ. I still don't know what I was thinking. I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I witnessed a fellow amateur attempting to guilt another into using LoTW with comments about how their QSO partner would appreciate confirmation via the service, even if they didn't care for it. Before I continue, if you're unfamiliar, when two amateurs make a contact, or a QSO, with each other, then there's generally a log entry at both ends to record the event. Some amateurs, myself included, save up these contacts and count how many continents, countries, states and other entities are recorded in the log. Several amateur radio organisations allow you to claim an award for such a record. However, before they accept your word for it, they require confirmation of the contact, something that the amateur community refers to as a QSL. To recap, a QSO is the contact, a QSL is the confirmation of that contact. Traditionally this was achieved with postcards, known as QSL cards, transported across the globe through various postal services, and coordinated by so-called QSL bureaus, often run by the amateur radio peak body in each country. With the advent of the Internet, much of this process has turned electronic. LoTW is an example of an electronic QSL service, run by the ARRL, the American Radio Relay League. It's not the only such service, but today I'm looking specifically at the Logbook of The World, or LoTW. As I said, LoTW is not the only service and anyone telling you that you must use it is selling you something. Now, that's not why I don't use it, and again, you're free to, but you're not required to. For me there are several issues with LoTW. Having used it for a period, I feel comfortable in expressing some of its shortcomings, but I note that the last time I used it was almost a decade ago. I'll acknowledge that things might have improved or changed, but I have no evidence to suggest that it did. Let's start with how it works. You create a log in a specified format, using an application called TQSL you sign that log, ostensibly linking your identity to that log, then you upload that signed log to LoTW and wait for confirmations of contacts with other LoTW users. Signing is a process where you add information to a file that proves to the recipient that the log was created by you and wasn't modified in transit, which requires that you have a file called a certificate, which is created and sent to you via email by the ARRL, after they've authenticated you. So, first of all, in my opinion, the level of security is absurd and exceeds that of my bank, or my tax department. In addition, proving your identity comes with hurdles if you're not in America where an amateur who registers receives a postcard with an authentication code, made possible by the central database held by the FCC. For everyone else, the ARRL requires that you: "must send a copy of his/her Amateur Radio operating authorization in addition to a copy of one other government-issued document indicating his/her identity", via the post, snail mail, stamp, envelope, the whole thing. I'd also like to observe that at no time has the ARRL linked your identity to your email address, since they haven't asked for it at any point in the verification process. If that's not enough of a security nightmare, in Australia and other parts of the world, amateurs no longer hold a personal license, instead they are members of a so-called class license. There's no public record stating my ownership of my callsign, just that it's allocated. With increased privacy concerns, this is happening elsewhere too. In other words, proving that you are who you say you are is getting increasingly difficult and even if you did, you're sending that information to the ARRL, who you might recall paid a ransom to hackers who infiltrated their network. I've asked and never received a response about what actually happened to the information they continue to hold in relation to me, well that and an email from 2013 which states that "Data is never removed from LoTW." Even so, let's say that you are comfortable sending your information to the ARRL, the process of signing a certificate requires renewal on a regular basis and if you manage to forget, you have the privilege of starting all over again. Let's move on. It's important to remember that this process is to confirm a radio contact between two radio amateurs in order to get a piece of paper to hang on your wall saying that you did so. How do you know that the person you made contact with on-air is the same person who confirmed your contact? Radio isn't authenticated in any way, why should the confirmation be? Remember, before the Internet, this was done with postcards. Security and authentication aside, there's plenty more issues. I hold the callsign VK6FLAB. Several times a year, that callsign is permitted to be AX6FLAB. I like to operate portable in many different locations. Sometimes I sign "/QRP" for low power, generally if the other station is very high power and they're struggling, adding QRP can sometimes act as an incentive to complete the contact. Sometimes I sign Portable, or Mobile, depending on the situation and when I'm moving, I'm not in a specific location. Why am I raising this you ask? Well, turns out that you need to make a new location for every single one you're operating from. You also need to register each callsign and each variation, since apparently VK6FLAB and VK6FLAB/QRP are two different stations and if I sign with AX6FLAB, I need to request another certificate. So, this is increased convenience .. apparently. Then there's the argument that you're missing out. Let's get this straight. As far as I can tell, the bulk of LoTW users are American. For me, a contact with America is a single log entry to add to my continent and country list. Tell me again why I should care about this when I'm not in America? There's a list of 340 DXCC entities, which you can buy from the ARRL for $5.95 plus shipping, because of course in this digital age there's a shipping charge. In other words, this is the ARRL attempting to own the notion of confirming contacts between radio amateurs and in my opinion, being obnoxious about it. Here's another issue. If this was really so marvellous, why hasn't any other peak body adopted the Logbook of The World for their system? Why is there not a WIA version, an RSGB one and for each of the various countries who have closed their local QSL bureau due to lack of funding, since the postal burden on them has exploded to become nonviable? I think that LoTW is a solution looking for a problem, peddled by people who have something to sell and while there was a time that it might have been bleeding edge, that ship has sailed. You're free to use it, but I wouldn't recommend it. If you have never stepped into this, alternatives to explore include ClubLog, eQSL, QRZ, OQRS and plenty of print on demand QSL card services. And if you're searching, apparently QSL is also Queensland Sugar Limited, so pay attention. I should also mention that there's SOTA, Summits, POTA, Parks and other On The Air services that will happily take your log and confirm contacts. Here's a thought, how about we use the fediverse to federate and decentralise the process, or perhaps we might use something as mundane as email. If you want to use LoTW, by all means, go right ahead, but I won't and if I knew how, I'd get the ARRL to remove all my records from it, mind you, I'd have to trust them at their word, because I can't log in to check. I'm Onno VK6FLAB

Foundations of Amateur Radio Recently I discovered that the antenna that I had connected to my WSPR or Weak Signal Propagation Reporter beacon was not a 40m antenna, instead, it turns out to be a 15m antenna. The how and why of that mix-up isn't particularly helpful, so instead I set out to remedy the situation. Step one was simple, go into the garage and pull out the antennas and check if I had forgotten about an 80m antenna. As it happens, I'd forgotten about a 17 megacycles antenna. At the moment I couldn't tell you if it was intended for Maritime or Amateur use, but it doesn't really matter, since I'm not permitted to use those frequencies for transmit and I was on a mission. Oh, I also discovered that you can dislodge two shelves with stuff on them by moving an antenna. Fun. So, 7 MHz, or 40m it is. The antenna mount is clamped with G-clamps to the side of a steel roofed framework that's bolted to the house. It's been there for about eight years or so. From time-to-time I change over the antenna depending on my mood. Today I wanted to move the mount and after taking it down decided that it could do with a little maintenance, least of which due to the fact that the feed-point connector had detached itself. I also needed to remove the ground wire, which turns out to be a bit of a palaver, since my socket wrench adaptor has gone walkabout and the 10 mm socket that fits into the next size is too large. Eventually I found an imperial socket with a matching wrench to undo the thing. Then I set about moving the mount to a new location, tucked inside a tree, so plenty of branches to poke me in the eye, or the belly, depending on which was handy at the time, and discovered that the steel beam was thicker, to the point that my G-clamps were 2 mm too small. So, I spent some quality time comparing hardware store offerings, finally found a bigger G-clamp for a reasonable price, but in the process discovered customer reviews and photos showing that the clamps fail if you hand-tighten them. Me being the "if you can move it, it's not tight" kind of person, figured that this would not work. Found F-clamps at a different hardware store and went on my merry way to get one. The hardware store was undergoing maintenance, so hammer drills and stuff everywhere, more fun. After getting back home I discovered that the new location was great in theory, but in practice it turns out to be less than spectacular, since the beam has a slight curve in it, making for a poor clamping surface and no place to put two clamps. Back to the original location. Using the new clamps, fighting for space, I realised that I could re-use the old clamps, so swapped them over. Then I got to the point of connecting the feed-point and discovered that my 40m antenna is missing the mounting thread and the all-thread inside the old antenna wouldn't budge, neither would any of the threads in the other two antennas. So, at this point, three hours in, I came to the realisation that this was going to be a 15m antenna or no antenna. So, 15m it is. There is one actual change. I discovered that the feed-point connector is actually an SO-239 socket and the connector to it was a standard banana plug which in turn was connected to a BNC connector, with the shield connected to ground. I realised that I could use a BNC to PL-259 adaptor instead to connect the RG6 coax to my antenna. This means that the coax is now directly connected to the feed-point, rather than through a weird cobbled together BNC-to-wire-split-thinga-ma-bob-contraption. It looks very pretty. Measuring the result also shows some changes. On both 40m and 15m the SWR is still the same, on 10m it's a little worse and on 2m it's significantly better. All in all, I think this is a perfect example of 17 steps backwards and 18 steps forward. I suppose it could be worse. I'll let you know how the beacon goes. Now, I should probably log this. Something like: "QTH HF antenna mount maintenance, nothing changed, 15m antenna, PL-259 to BNC adaptor to replace homebrew wire splitter. 3 hours." I'm Onno VK6FLAB

Foundations of Amateur Radio About a year ago I set upon a new adventure, to determine if the dummy load I own, traditionally seen as a device that doesn't emit any RF, to determine if it was in fact imbued with the ability to absorb RF, rather than share it around like an antenna might. At this point you might be shaking your head, but this wasn't embarked upon lightly. I had spent several years experimenting with lower and lower power levels and came to learn that even 10 mW can make it to the other side of the planet, 13,945 km away. In other words, extremely low power can, under the right conditions, make it across the globe. So, with that in mind I connected a dummy load to my WSPR beacon and configured it to transmit across each band between 80m and 10m and then set-up an RTL-SDR dongle to monitor those same bands as well as the remainder of the amateur bands within the range of the dongle. I did this because I wanted to make sure that if there was any chance of a harmonic appearing unexpectedly, there'd be a good chance I'd see it. Then for a year I did nothing. Well, not exactly, but we'll get to that. After downloading 16 months of WSPR reports I extracted all the records that had my beacon in it and separated them into two groups. Those that had VK6FLAB as the reporting station and those that didn't. Both contained a significant number of signal reports. After doing some analysis, charting the efforts and discovering other phenomena, I can report back a little of what I learned. The dummy load does radiate, but I only saw reports from the dongle which is in the same room. I have already talked about this and at the moment the working theory is that the coax between the beacon and the dummy load radiates, or the beacon itself does, or something else, because the RTL-SDR dongle is clearly and accurately decoding WSPR signals. I'm not sure how I'd go about verifying where the radiation is coming from exactly or if I'd need equipment that I don't have or know about. That said, somewhat to my surprise, the signal reports were not static, varying considerably by as much as 40 dB. Notice that we're talking about a signal that is being, at least ostensibly, transmitted into a dummy load and being received on an external antenna. The signal reports don't appear particularly affected by time of day or band, that said, there's a visible range of reports across the year, but it's hard to observe anything definitive since most of September and October is missing. At this point I cannot tell you why that's the case. More on this in a moment. I did notice that some odd things happened to reports throughout the year. For example, on 40m, the reports were significantly poorer in the first half to 2025. 17m and 15m on the other hand were worse in the second half of the year. On the 25th of April here in Australia we're permitted to change our callsign to use AX as a prefix, so my VK6FLAB callsign would be AX6FLAB. On that day I configured my beacon to use 40m and connected it to the antenna for the first time in a year. I had several reports across the Great Australian Bight over 2,000 km away. At midnight UTC the next day I changed the callsign back to its normal VK prefix and changed the bands to use 80m, 40m, 15m and 10m, and left it connected to the antenna. While the antenna is a mono-band antenna, I wanted to know if it would still radiate on bands it wasn't intended for. Turns out that yes, it does, very nicely in fact. Since activating it like this, I've been heard by 79 different stations, as far away as 15,649 km in the United States, and in Antarctica as well as across Europe and several reports in Africa, the bulk in the Asia Pacific. Something curious though. I noticed that there were no reports on 80m and only a few on 40m. Pretty evenly split are reports on 15m and 10m. This was odd to me, since I would have told you that the antenna is a 40m mono-band antenna. You might recall, built by Walter VK6BCP (SK), I was given several antennas that are essentially helically wound verticals. I've used these ever since. I was adamant that I'd changed my antenna to 40m. After scratching my head for a bit, I decided that measuring might be a good idea. I discovered that the SWR, the Standing Wave Ratio, a traditional measurement of antenna effectiveness, on 80m is infinite, it's high on 40m, over 3 to 1 on 15m, just on 3 to 1 on 10m and similar on 2m. In other words, this is probably a 15m antenna. Now here's some things to observe. Based on reports across Australia, this antenna still radiates my 200 mW beacon on 40m, even though the SWR is 17.5 to 1, yes, you heard that right. This by way of noticing that the SWR has a relationship with how your antenna functions, but you might know, a dummy load has a perfect SWR of 1:1, in other words, the SWR is one way of characterising your antenna, but clearly it's not the final word on the ability of your antenna to get on-air and make noise. I've said it before, any antenna is better than no antenna. This left me with a growing sense of unease. Several of my measurements are missing, I wasn't using the antenna I thought I was, I don't recall exactly when I switched over from my 10 mW antenna experiment to my 200 mW dummy load, and no doubt there's other things that are lost, like local thunderstorms that encouraged me to disconnect my external receive antenna, or when I rebooted a frozen computer that wasn't decoding anything, or when the internet was down, not reporting to WSPRnet.org. Some of these things I can reconstruct. For example, I can roughly see in the logs when my beacon was reconfigured to 200 mW, but was it still connected to an antenna, or did I immediately connect the dummy load? I came to realise, probably again, that I should keep better notes beyond those that make it into my weekly efforts here. So, I built a "lab-notes" tool that will help with that. It's on my VK6FLAB GitHub page and consists of a single bash script that takes care of business. The notes are also stored on GitHub, so you can follow along. Feedback welcome. Admittedly, this still requires that I take notes, but at least one friction point has been removed, namely a place to make such notes. Feel free to make your own. In the meantime I'm going to figure out if I have an 80m antenna lying around and if I can use it with my beacon across multiple amateur bands. I'll make a note when I do. I'm Onno VK6FLAB

Foundations of Amateur Radio Several years ago, I forget exactly when, I was gifted a device called a "Wio Terminal". It's a micro-controller in a box with a screen, buttons, Wi-Fi, Bluetooth and a boat load of sensors, ports and more. It's intended for experimentation and truth be told, exactly the right gift for a geek like me. It even has rubber feet to stop it from sliding off the desk, well, slow it down at least! The thing is, it remained sealed in its box until this week, when I finally gathered enough unrelated information, something I often refer to as "puzzle pieces", to understand what this device might do and how I might use it. Given that I'm talking about amateur radio, and not software development, I'll only mention that I got my initial "hello world" working and observe that I have some radio projects in mind for it. What this experience revealed to me was that complexity is hard, not to mention frustrating, and not limited to my adventures with computers. Let me elaborate. In amateur radio the answer to a great many questions is a phrase I've used before: "It depends", a valid, but ultimately immensely irksome response. Over the years I've attempted to dig into what exactly "it" depends on, with varying levels of success. While Earth rotates on its axis, that answer is unlikely to change, but I think I can make it potentially less aggravating, and here's how. When you come across a question where the answer is: "It depends", stop worrying about exactly "what" "it" depends on, instead, keep the question in mind whilst you go about your life. Looking back at my Wio Terminal experience, that's exactly what I did. While there's the frustration of not being able to report to my friend that I'd done anything useful with it, by having it float around my desk, albeit still in the box, I regularly noticed it, and when going about my day I'd continue to gather puzzle pieces that eventually hit a critical mass. In other words, whilst gathering apparently unrelated, facts, skills, articles, example code, cables, computing resources, how-to documents, forum posts and the like, including having discussions with others, eventually I had enough to realise that I had the answer to my question that wasn't "It depends", instead, I had a clear, well, clearer, understanding of what kinds of things I needed to achieve to make progress. Now I'll be the first to acknowledge that this journey isn't always a gentle stroll in the woods, "bear with a sore tooth" has been levelled more than once, but the point remains, figuring out how things work isn't a linear process and once you are aware of that, life becomes, well, at least in my mind, more interesting. Again, what does this have to do with amateur radio? Well, let's look at some innocuous questions that an amateur might ask: "What radio should I buy?", or "What antenna should I get?", or "Given the current propagation, can I make a contact with my friend on the other side of the planet?" The answer to each of these questions is: "It depends." If you have been in this community for a time, you'll understand some of the things "it" depends on, but the longer you are here, the more aware you become of other things "it" depends on, in other words, your understanding of the problem reveals that there are more considerations at play that might not be immediately obvious. At some point you'll get to the next unhelpful response in amateur radio: "Try it and report back." Equally annoying, since, at least on the face of it, you'll invariably be left with the feeling that nobody cares, least of all the person you asked. While I'll acknowledge that this is sometimes the case, on the whole, the response really reveals that there are too many unknown variables to form any coherent overview. That said, as the person answering, providing a range might be helpful to at least get a sense of what space to play in. What I mean by that is, sometimes figuring out what needs to happen involves multiple considerations which each impact on the solution in subtle and different ways. When you're learning about a problem, you might not know what those considerations are, but as time goes by, while you're presumably collecting puzzle pieces, your awareness increases. During the week, I saw a post by Christophe ON6ZQ announcing a tool called "HF Propagation Lab" (https://on6zq.be/prop), described as "A browser-only teaching instrument for amateur radio operators. It explains what live space-weather numbers suggest, how each band may react, and which ionospheric mechanism is probably doing the work. It is a teaching model, not a substitute for beacons, skimmers, WSPR, or listening on the air." What this tool does is give you a feel of the propagation landscape you're playing in, what variables impact in what way, in your ability to make contacts. In other words, it's a way to learn about the unknown variables associated with propagation. So, when have you been the recipient, or donor, of the phrase: "It depends.", or "Try it and report back.", and what might you do to improve things next time? I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I went for a walk around the block for the first time in a while. It's something I did for a time and then for several reasons, mostly to do with health, didn't. For me it's the mental equivalent of having a shower with the added benefit of not having to dry my hair, in other words, it's a place I go to with the intent of generating shower thoughts. During my walk, away from the forces pulling me in all manner of directions, none of which have anything to do with amateur radio, away from my keyboard, away from my screen, away from technology challenges, although I'll admit that my phone was in my pocket, I took about twenty minutes to walk and daydream, to follow my thoughts and to see where they'd end up. I got to this point because sitting at my desk I was getting nowhere trying to put together my thoughts in any sequence at least resembling coherence. While it's happened before, it's not something that occurs often. The day before I'd started writing, almost as-if possessed, about what amateur radio means to me, but during my walk I started wondering about the people who leave this hobby and the community embracing it. I've often said that F-troop is a weekly net for new and returning amateurs, both people who have a license that's still hot off the printer, and others who have one typed up on an IBM Selectric, signed with a quill, ink faded with age, paper yellowed by sunlight, potentially with coffee mug rings on it, stashed somewhere in a drawer. I wondered about those returning amateurs and asked myself about the nature of leaving a hobby. It occurred to me that people leave for many different reasons, and it would be foolhardy to consider that all of those reasons are controllable by our community. While bullying and arguments exist, each responsible for their share of people leaving, it seems to me that some amateurs leave because there's too much other stuff going on in their lives, things that actively or passively prevent amateurs from participating. This is difficult for me to relate to because for me, amateur radio is an intrinsic part of my life, in that it often quietly shapes how I view the world and learn from it. I see it when I notice a television antenna pointing in the wrong direction, when I install a new Wi-Fi router somewhere, when a signal is lost to a manned mission around the Moon, when I open the garage door and when I read that researchers at the National Institute for Standards and Technology, better known as NIST, have developed a new method for creating chips that process photons similarly to how traditional chips process electrons which can generate a rainbow of colours, though they didn't use the letter "u" to describe them. While those examples might be somewhat obvious, amateur radio is also there when I see someone share a tiny electronic paper screen on social media and I consider how I might use that when I go portable. It's there when I'm walking in a park and when I'm looking at a beach, it's there when I see metal artworks or painters poles at the local hardware store and when I watch a movie with radios anywhere on screen. It's there when the topic of physics arises and when some electromagnetic phenomenon occurs. Like radio waves and air, it's pretty much part of my daily existence. I will add that this same depth of connection exists between me and computers. Watching "Flight of the Conchords" I cannot help but notice that Murray's computer keeps changing and that I miss the Commodore Vic 20 sitting behind him surrounded by ever changing New Zealand tourism posters. In other words, I cannot imagine ever not having radio or computers in my life. I'm mentioning all this because my experience isn't universal. While I'm sure that I'm not alone in this deep affinity, the community as a whole invariably ranges between people who could take or leave the hobby at a moment's notice and those who couldn't live without it and beyond our community there are people who are, depending on your perspective, blissfully or woefully, unaware of our existence. All this to say, your experience of this hobby is not the same as that for everyone else, neither is your experience of life. This is revealed more clearly in what we think the hobby means, whether or not FT8 is a blessing or a curse, contesting is ridiculous or amazing, why 40m is better than 20m or vice-versa and if the hobby died when the ITU stopped requiring Morse code, or saw a rebirth. It should be obvious by now, but I think it's important to be explicit. Amateur radio is your hobby. It's what it means for you. Not for your mate, not for me, not for the people in your club, the local email list or social media. Just you. So, use this as an opportunity to think about this, in my not so humble opinion, absolutely amazing hobby and what place it has in your life. I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I came across a post on mastodon.radio by Keith W6KME announcing the resumption of the Micro Field Day, spelled using the 12th letter of the Greek alphabet, Mu. This was news to me, since I didn't know they'd stopped, let alone existed at all. Being the curious type, I stopped to investigate and discovered an initiative that could, and in my not so humble opinion, should, be replicated all over the planet. Essentially an informal monthly gathering of amateurs with their portable set-up, ranging from hand-held radios through lightweight backpack gear suitable for SOTA or POTA, or Summits or Parks on the Air, to car portable stations where your vehicle acts as the carry mule and perhaps the base of your antenna. In other words, it's for anyone who brings along their radio to play or if you're not yet ready to do that, come and participate as you feel inclined. So, what of the resumption, you ask. It turns out that the activity became so popular locally that some parks required paid bookings and insurance, which is somewhat challenging if you're not actually an organisation. The closest I've ever come to a Micro Field Day is when we celebrated a milestone anniversary for the weekly F-troop net that has now been running for over 15 years. The Bored Net Group website has plenty of information about what they get up to during a Micro Field Day, Random Metal Objects On The Air, shared club activities, picnic lunches, and activations at local lakes, landmarks and other places of interest. I'd also like to make a point here about documenting your activities so the rest of the community can learn from your experience and the Micro Field Day isn't the only, or even the first activity that the group organised. Special mention to Zak N6PK who started hosting the BORED net four times a day during the COVID-19 pandemic lockdown in March 2020. You'll find the full story when you check out their site at theborednet.net for that and oodles more inspiration. While I'm perfectly happy sitting at home behind a computer reading research on the resource comparison between half a dozen algorithms for calculating a Fast Fourier Transform, that's not the only thing that amateur radio represents. When I started running F-troop there was no place for new and returning amateurs to gather and ask questions and share their experiences. Today the log shows at least one new callsign for each week we've been on-air, representing nearly a thousand amateurs who activated their transmitter and shared their experience. There is no organisation behind F-troop, it's a couple of amateurs who regularly turn up and participate to act as a welcoming voice into the diverse community that represents amateur radio. In other words, it started because I felt like it and it continues because people keep coming back. The Micro Field Day is exactly the same in that it was started to scratch an itch. I'm making this explicit because some amateurs appear to be under the impression that they'll need a local club or organisation to organise activities for them. I'm here to tell you that you can start such an activity with your friends. Ultimately, where do you think clubs come from? So .. what are you waiting for? Get on-air and make some noise! I'm Onno VK6FLAB

Foundations of Amateur Radio The other day fellow amateur Randall VK6WR raised an interesting question. Using his HP 8920A RF Communications Test Set, which you might recall from our adventures in measuring radio harmonic power in 2023, that report is on my Github repository, but I digress, Randall wondered if the signal strength he was seeing on several radios were the same and discovered that in fact they were not. It made Randall ask who set the standard and following on from that, what does this look like in the real world? In 2014, episode 149 of the series "What use is an f-call?", I published an article titled "The simple S-unit". In it I referred to a standard for S-units defined in 1981. Unfortunately, I didn't provide any references, so, armed with more than a decade extra experience, Randall encouraged me to investigate. Twenty seconds into my search, I discovered IARU Region 1 Technical Recommendation R.1, which has four statements related to the topic at hand. Under the title "STANDARDISATION OF S-METER READINGS" it states that: 1. One S-unit corresponds to a signal level difference of 6 dB, 2. On the bands below 30 MHz a meter deviation of S-9 corresponds to an available power of -73 dBm from a continuous wave signal generator connected to the receiver input terminals, 3. On the bands above 144 MHz this available power shall be -93 dBm, 4. The metering system shall be based on quasi-peak detection with an attack time of 10 msec +/- 2 msec and a decay time constant of at least 500 msec. So. Job done, right? Yeah, nah, not so much. The web page I quoted from is linked from the Wikipedia S-meter entry and was archived in 2005 and at the time existed on a Swedish domain in the home directory of Kjell SM7GVF. The page has two additional interesting things, the words "Brighton 1981" and "Torremolinos 1990", both of which refer to IARU conferences. The reports for these meetings are online. In searching for any reference to the definition of the S-unit, the 1990 report shows that resolution "83-1" had the status of "Action completed", whatever that means. The 1981 conference document has all manner of interesting references, including "Log Forms and Summaries for International Contest Use", "Meteor Scatter qso procedure" and the definition of the standard way to determine Morse Code speeds using the word "PARIS" followed by a 7 bit word space, to name three. The one we're interested in is called "BM/134 - S-Meter Standards", appearing on page 33 and 34 of the 1981 report. It's a photocopy, so you can see the text from other pages superimposed. I'm making this observation because this is essentially a standards document, intended to be adhered to by industry and the amateur community. It gets better, or rather .. worse. The text that is referenced by Wikipedia uses numbers for the four elements, where BM/134 uses letters. The third item in BM/134 says that it applies for "bands above 30 MHz", but the document I just quoted appears to be unique in saying that it applies to "bands above 144 MHz". The fourth item, dealing with the way that the meter responds has been altered on BM/134. The text "+/- 2 ms and a decay time" are in a different font and at an angle. Worth noting that the change includes "ms" twice, rather than "msec" as the unit for milliseconds used elsewhere. Searching for a phrase within the standard, I discovered the Region 1 HF Manager Handbook v7.01, which appears to include the S-meter standard in chapter 11.1.2, but closer inspection reveals that the fourth item is missing, the one about quasi-peak detection. This is significant because the S-meter standard is based on a CW signal, not an SSB signal, which fluctuates. There's no reference as to where or when this was removed or by whom. These changes are repeated in subsequent versions of the HF Managers Handbook. There's other differences too, instead of using millivolt and microvolt as shown in the original BM/134 standard table, all units have been converted to millivolt for no discernible reason. The new table, including typo, is also copied everywhere. While we're at it, the original standard contains the letters "V", "E", "R", "O", "N" at the top. They don't show in the HF Managers Handbook either. This is curious, since last time I checked, those letters signify an organisation that at least some here will recognise, the "Vereniging voor Experimenteel Radio Onderzoek in Nederland", known to the the people who don't speak fluent Dutch, as the peak body for amateur radio in the Netherlands, VERON. Searching its website does not reveal their contribution to this standards document, which I have to say, is par for the course, much of our amateur radio history is poorly documented or archived, if at all, something which I've spent plenty of my time attempting to remedy over more than a decade, one article at a time. Moving on. The phrase I mentioned earlier bears reading out in its entirety. From BM/134: "We hope that the current recommendation will be followed by all equipment manufacturers, so that in a not too distant future one will know how to interpret the strength report of the other station." It goes on to say: "Societies should advise as much as possible their members about equipment manufacturers adhering to this recommendation and shall try to avoid publication of receiver designs which do not in principle use the recommended standards." Which brings me to you. What have you done lately about this? It's only been 45 years. Perhaps it's time to implement this? I can tell you that preliminary results show that the S1 level sensitivity associated with the radios that Randall showed me are reporting S1 when really they should be reporting about S4. You might wonder why this is the case? Calibration appears to be the underlying cause. While S9 itself is variable in accuracy, as-in some radios are more accurately close to -73 dBm, others are consistently 5 dB shy of that. When an S4 signal is reported as S1, then the 6 dB step size is not correctly implemented. Similarly, when an S9+20 is reported by a signal that's only 16 dB stronger than S9, there's more fudging going on. The differences between a signal with and without preamp are also worth noting as being inconsistent. In other words, the level and steps associated with S-meter units are all over the place, which is interesting, since the authors of the standard already alluded to this when 45 years ago they wrote: "Simple means for calibration of at least the 6dB level ratio should be published." While we're digging for causes. Why is there not a standards library associated with the IARU, where documents like BM/134 exist and with it their current level of application? Before you tell me, money, I'd point out that in 1981, IARU Region 1 had 263,945.88 dollars, or francs, guilders, pounds or glass beads in the bank, it's unclear which, since there's no units stated. At the 1990 conference IARU Region 2 had a reported net worth of $150,000 with $40,000 annual income and Region 3 reported that "its finances are also sound". How do I know? That's in those conference documents too. Curiously, the 1981 report states that "when presenting the 1981 and subsequent accounts the Treasurer would also prepare a brief report which would explain the reasons for items of such expenditure for which the purpose was not obvious." I wonder what happened to those explanations? So, what is the current status of BM/134 and what are the legal implications of me publishing it on my Github page? While we're at it. I realise that I can "fix" the Wikipedia page, but where do I point it at? I'm Onno VK6FLAB

Foundations of Amateur Radio The thing I love most about this amazing hobby of amateur radio is the sheer size of the community and the depth of knowledge that comes with it. Case in point, the other day I mentioned the spark gap transmitter at Grimeton in Sweden. A few hours after releasing my comments into the void I received a message from Paul SA7CND who lives, wait for it, 153 km from the transmitter. He's been on-site while it was running, transmitting on 17.2 kHz. Paul pointed out that the Grimeton transmitter is not a spark gap transmitter at all. It's actually an Alexanderson alternator, an entirely different beast, and all the more interesting for it. Invented by Swedish electrical engineer and inventor, Ernst Frederick Werner Alexanderson, he received a patent for it in 1911 whilst working for General Electric. He died in 1975, aged 97 with 345 patents to his name. Before I dig in, because you know I will, the transmitter at Grimeton was officially opened on the 1st of December in 1924. Built to increase Swedish independence after World War I revealed its vulnerability to foreign controlled transatlantic telegraph cables. Serving as a telegraphy station capable of transmitting traffic across the Atlantic ocean the station was in regular service until 1996. Unlike its scrapped brethren, the Grimeton transmitter is currently operated several times a year as a functioning transmitter using the callsign SAQ. Announcements are made on the station mailing list and the website at grimeton.org, but generally on Alexanderson Day in July and Christmas Eve in December. You'll need to tune to 17.2 kHz, something you can do with a sound-card, or with an SDR. Sound-card you say? Yes. Not for audio, but for RF. Connect an antenna to the microphone centre-pin input and have at it. Note that this will likely be highly susceptible to noise, so filtering and experimentation are to be expected. There's several tools around to play with this, GNU Radio, Quisk, SuperSID and SAQrx. Also, there's plenty of other VLF, or Very Low Frequency stations to listen to. I should probably add this as a 51st thing to do with SDR, but I digress. Back to Grimeton. As the last remaining functional Alexanderson alternator transmitter, it was added to the UNESCO World Heritage List in 2004. You can visit and see first hand what radio history looks like. As I said, if you pick your day, you can even watch it working. Failing that, there's plenty of YouTube videos showing the entire process, it's an absolute monster. There's even an amateur radio shack on-site with the callsign SK6SAQ. The website says that it's open sporadically, so I'd recommend you contact them before heading to Grimeton. I'll note that at the time that this station was being commissioned in 1924, it was already being superseded by valve oscillators, which brings me to how it works. Depending on where you live, you're likely familiar with the 50 or 60 Hz alternating current associated with household electricity. In 1891, Irish experimental physicist Frederick Thomas Trouton pointed out that if you could run an alternator at high enough speed it would create an alternating current at radio frequencies, said differently, creating a continuous wave at radio frequencies. Much experimentation followed and many giant shoulders supported this effort. It goes a little like this. Use an electric motor designed to spin at 900 revolutions per minute. Connect it to a gearbox. Connect that to a rotor with multiple poles. Then run the motor with a clutch to vary the speed. If that's not enough, to produce high power, the clearances between rotor and stator have to be kept to a millimetre. Then there is cooling and lubrication to consider, not to mention dealing with thermal expansion and contraction of a fast spinning and closely toleranced disk. At Grimeton, the whole transmitter weighs in at 50 tonnes, pretty much the opposite of portable operation. The rotor at Grimeton is a 1.6 meter diameter disc with a 7.5 cm thick edge with 488 slots milled into it, each filled with brass. The motor at Grimeton runs at just over 711.3 revolutions per minute, the gearbox has a ratio of 2.973 and the whole contraption generates 17,200 Hz. If you get the sense that you're balancing an elephant on top of a needle, you're almost there, but if you consider that keying the transmitter changes the load and currents, it's more like an elephant being shoved by a train, balancing on top of a needle. At Grimeton, the motor is loaded by one of three liquid resistors, which each consist of a two metre high container filled with water and baking soda. The liquid level is controlled by separate pumps, varying the resistance. Whilst transmitting, a second liquid resistor is added, reducing the resistance to regulate the speed of the motor to maintain the overall speed and the associated frequency. The resistors generate heat which is fed through a heat exchange to the station's water cooling system. The third resistor is available as a spare. The remarkable thing? It works. So much so, that there were several stations built and operated across the planet. There's more. This system is also capable of Amplitude Modulation, and with it, the ability to send the human voice across the airwaves. As an aside, there is a rotating spark-gap transmitter by Canadian electrical engineer and inventor Reginald Fessenden who is said to have given voice to radio in 1900 across a 1.6 km distance, but that's a tale for another day. The frequency that Grimeton transmits on, 17.2 kHz, means a wavelength of nearly 17.5 km. The antenna at Grimeton is "only" about 2 km long, in other words it's a compromise antenna. I'm making a joke here, but also a point, every antenna is a compromise. Any antenna is better than no antenna. Meanwhile, the antenna at Grimeton looks like a string of high voltage pylons with eight wires strung between them. Each of the six towers is 127 meters tall, with a cross arm that's 46 metres wide. Every tower holds a vertical radiator, connected to the ßground via a coil to tune the phase and capacitance of each radiator. So, spark gap this is not, well at least not intentionally. This remarkable piece of engineering makes me wonder if you can use the same system to spin a modern motor, say the spindle of a CNC, and use it to get on air and make noise. Now all I need is someone to talk to. I'm Onno VK6FLAB