Foundations of Amateur Radio

Foundations of Amateur Radio Recently I spent some quality time digging into the origins of a word in common use. In doing so, I contacted the Postal Museum in the United Kingdom and received a lovely reply that included a photo of a document in their archive. The document, a Post Office Circular from Friday, December 30, 1904, number 1641, introduces a new service offered by the Post Office. Let me read to you what it says, and I quote: "Telegrams to and from Ships by Wireless Telegraphy. "(To be noted at Telegraph Offices only.) "With the present Circular is enclosed a list showing the wireless telegraph stations in the United Kingdom worked on the Marconi Company's system, and the hours up to which telegrams can be received at those stations for transmission by wireless telegraphy to certain ships fitted with Marconi apparatus. By another notice in this Circular, Postmasters and others concerned are requested to enter the names of the stations in the Code Book with the necessary particulars. Ships will be issued for insertion in the Post Office Guide. "On and from the 1st January, 1905, Telegrams may be accepted from the public on the following conditions:- "Subject to the Inland Regulations with regard to counting, the charge, which must be prepaid in the usual way by means of stamps, will be at the rate of 6 1/2d. [six-and-a-half pence] a word, with a minimum of 6s. 6d. [six-and-a-half shillings] per telegram. "The name of the wireless station will in each case pass as one word in the address. "The word 'Radio,' which is not charged for, should be telegraphed in the Service Instructions." When I read that, it made the hair stand up on the back of my neck. The introduction of a Wireless Telegram service, under the service heading of "Radio", with a photo of the actual document that introduced it into the world. I also learned that there's a dozen pennies in a shilling and over the years before decimalisation in 1971, the composition of coins changed, which made converting this into today's money interesting. As an aside, the Royal Society has a wonderful article: "The science of money: Isaac Newton's mastering of the Mint" Back to radio, this is 1904 bleeding edge technology and it's priced accordingly. The starting price for a radio telegram on new years day 1905: six bob and six; or three florin and sixpence; or a crown, a bob and a tanner; is worth just over 34 Great British Pounds today, that's just on 45 US Dollars, or nearly 69 Australian Dollars. That's the minimum price. The price per word, sixpence and halfpenny [sixpence hayp-ny] is just over 2 Great British Pounds today, nearly 4 US Dollars or almost 6 Australian Dollars. Compare that to the price of SMS, which started at about 21 cents here in Australia, today it's about 3 cents per message of 160 characters. This seems like a lucrative business to be in, but I digress, again. From my current, and ongoing research, it appears that until this point, the early 1900's, the word "radio" was always accompanied by another word, for example in this context, "radio telegraphy", another combination of the day is "radio active", as well as "radio tellurium", which today we know as polonium. Moving on, the response I received from the Postal Museum included other gems, including a reference to the "1904 Wireless Telegraphy Act", from the 15th of August, 1904, where I found something fascinating, from Section 2 paragraph 1: "Where the applicant for a licence proves to the satisfaction of the Postmaster-General that the sole object of obtaining the license is to enable him to conduct experiments in wireless telegraphy, a license for that purpose shall be granted, subject to such special terms, conditions and restrictions as the Postmaster-General may think proper, but shall not be subject to any rent or royalty." I think that's the birth of amateur radio licensing in the United Kingdom, right there. As an aside, because I cannot help myself, the...

Foundations of Amateur Radio If you use a word often enough it starts to lose its meaning. The other day, during breakfast, well, coffee, whilst playing one of our start-the-day with a smile word games, the word "RADIO" turned up. I grinned and pointed out that this was my favourite word, to which my partner mentioned that in Italian, it's referred to as "La Radio", which made us both wonder where it actually came from, did the Italian language import the word, or export it, given that Guglielmo Marconi was Italian? A quick search advised us that it came from Latin, radius, meaning "spoke of a wheel", "beam of light" or "ray". Fully enlightened we finished our coffee and got on with our day .. except I couldn't stop thinking about this. Having recently spent some quality time looking into the history of the RF Circulator, I figured searching the patent records might be a solid way to get some handle on where this word "radio" came from. Initially Google Patent search unearths the oldest as being from 1996, not very helpful. Adding 1900 as the end date filter turns up a radio cabinet patent with a filing date of 1833, except that it was published and granted in 1931, which is confirmed by the patent itself. This level of corruption in the data affects at least a dozen patents, but I daresay that there's plenty more like that. 1857 turns up a patent with the word "broadcasting", in the context of "broadcasting guano", so, nothing much has changed in nearly 170 years, but I digress. Adding quotes to the search term unearths a patent from 1861, apparently iron roads, locomotives, large slopes and small radio curves relates to the other meaning of the word radius, in Spanish. 1863 gives us ruffle stitching, "made upon the radio", but the patent is so corrupt that it's pretty much unreadable. 1871 unearths an electromagnetic engine, but the text has so much gibberish that I suspect that the word "radio" is a happy accident. 1873 shows us a "Wireless signalling system", bingo, the patent shows us transmitter and receiver circuits, antennas, messages and frequencies and a whole bunch of relevant radio information, except that the date on the patent itself is 1919. And you wonder why people argue about who invented what when? I'll spare you the gas apparatus, petrol lamps with cigar cutter, running gear for vehicles and bounce to 1897, "Method of and apparatus for converting x-rays into light for photographic purposes", the first occurrence of "radio", in the form of "radiograph", complete with pictures of the bones of a hand drawn meticulously from presumably an x-ray. I confess I'm not convinced. Using the United States Patent and Trademark Office search for the word radio gives you 54,688 pages with 2.7 million records, ordered in reverse chronological order with no way to skip to the last page. The World Intellectual Property Organisation finds the same Spanish iron paths patents, but unearths "A Differential Arrangement for Radio Controlled Race Cars" from 1900, but inside we discover it's really from 1979. Seems this level of corruption is endemic in the patent field, wonder who's benefiting from this misinformation? Meanwhile, still looking, I discovered the Oxford English Dictionary, which claims that the earliest known use of the word "radio" is in the 1900's, but the earliest evidence is from 1907 in a writing by "L. De Forest", but you are granted the privilege of paying them to actually see that evidence .. really? On 18 July 1907, Lee de Forest, made the first ship-to-shore transmissions by radiotelephone, which adds some credence to the claim, but I have to tell you, I'm not particularly convinced. Taking a different approach, starting at Guglielmo Marconi, his first efforts in 1894 showed the wireless activation of a bell on the other side of the room. Six months later he managed to cross 3 kilometres realising that this could become capable of longer distances. The Italian Ministry of Post and...

Foundations of Amateur Radio Recently I explored the use of a radio device aptly described by a fellow Aussie Electronics Engineer, "ozeng", as "Absolute witchcraft." .. I'm talking about an "RF circulator", one of which is sitting quietly on my desk, roughly 60 mm square, 30 mm thick, weighing in at just under half a kilogram, unexpectedly with a 200 year history. Let the spelunking commence .. The moment you start reading the "Circulator" Wikipedia page, you'll see this sentence: "Microwave circulators rely on the anisotropic and non-reciprocal properties of magnetised microwave ferrite material.", with a helpful reference to "Modern Ferrites, Volume 2: Emerging Technologies and Applications", a 416 page reference that promises to dig into the nitty-gritty, showing 55 hits for the word "circulator". Anisotropic you ask? It's the property that describes velvet, rub it one way, it's smooth, rub it the other way and the hair stands up on the back of your neck. Wood is another example, easier to split along the grain than across it. While we're at it, reciprocity in physics is the principle that you can swap the input and output of a linear system and get the same result. If you know me at all, it should come as no surprise that I went looking for an inventor. There's over twelve-thousand patents referring to a "circulator", including more than a handful relating to Nuclear reactors. In 1960, a prolific Jessie L Butler came up with patent US3255450A, "Multiple beam antenna system employing multiple directional couplers in the leadin", which states: "This circulator has the characteristic that energy into one port will leave another port to the exclusion of a third." If you recall, that's the exact phenomenon I used to describe the "RF circulator" on my desk. So, job done, we have our inventor. Not so fast. The patent goes on to say: "Circulators of this type are discussed in an article 'The Elements of Nonreciprocal Microwave Devices' by C.Lester Hogan in Volume 44, October 1956, issue of Proceedings of the IRE, pages 1345 to 1368." The IRE is the Institute of Radio Engineers. I found a copy of that tome, thank you worldradiohistory.com, which includes the following sentence: "Until a few years ago, all known linear passive electrical networks obeyed the theorem of reciprocity. Today several different types of passive nonreciprocal microwave networks are in practical use". A footnote refers to an article by Lord Rayleigh, "On the magnetic rotation of light and the second law of thermodynamics" and includes images of an optical one-way transmission system from 1901. In that 1901 article, Lord Rayleigh in turn refers to a paper published sixteen years earlier in which he observed that light polarisation can be made to violate the general optical law of reciprocity, using a system that consists of two so-called Nicol prisms, a crystal that can convert ordinary light into plane polarised light, invented by William Nicol in 1828. Using two prisms, arranged at a 45 degree angle, you can make light go through it in one way, but not the other. Lord Rayleigh, also known as John William Strutt, in a very sparse footnote, states: "That magnetic rotation may interfere with the law of reciprocity had already been suggested by Helmholtz." Further digging gets me to an 1856 publication of the "Handbuch der physiologischen Optik", or the handbook of the study of how the eye and brain work together, where Helmholtz says that, translated from German, "according to Faraday's discovery, magnetism affects the position of the plane of polarization." This gets us to 1845, where Michael Faraday experimentally discovered that light and electromagnetism are related. His notebook has the following sentence, paragraph 7718 written on the 30th of September 1845: "Still, I have at last succeeded in illuminating a magnetic curve or line of force and in magnetising a ray of light." Today we call that the "Faraday effect" The best part? You...

Foundations of Amateur Radio The other day I saw a post by fellow amateur Gary N8DMT who mentioned an "RF circulator" and a PlutoSDR in the same sentence. Amplified by a response from a fellow Aussie Electronics Engineer, "ozeng", who helpfully added a link to a Wikipedia article about circulators, it finally twigged that I had such a gadget in my possession and for the first time I realised how I might use it. Now, before I continue, I'll preface this with a disclaimer, this is a hand-wavy description of what this very interesting device does. "ozeng" calls it "Absolute witchcraft." and that's an apt description if ever I've heard one. Imagine for a moment a radio with separate transmitter and receiver connectors, attached to the same antenna using a T-piece, as-in, there's a run of coax coming from each connector, joined together with a T-piece, which in turn is connected to an antenna. The aim of this, don't do this at home contraption, is to avoid the need for two antennas, but, and it's a big one, doing this will very likely destroy your receiver the moment you transmit for the first time, because likely half the transmission will go to the antenna, while the other half makes its way to the receiver, which is not going to be something you want to happen, unless you like the smell of magic smoke. You might think that adding an attenuator, something that reduces the power on the receive port would help. Well, yes, it would, but as a side-effect, it would also reduce the signal coming from the antenna. At that point you'll decide you need a switch. Initially you might switch this manually, but that's a pain if you're wanting to transmit and receive continuously and need to remember in which position the switch is in. The next step is to use an electronic switch, like a relay. It can trigger based on some signal from the radio when it's transmitting and turn off the receive path during a transmission. This raises an issue with delay. Do you trigger just before you hit the PTT, as-in, time-travel, or do you delay the transmitter until after the relay has switched, which will cut off the beginning of your transmission? You'll likely have heard this kind of issue when listening to a station using an external amplifier. Their signal either jumps from low power to high power after they key up, or you miss the beginning of their callsign. Not to mention that if you get the delay wrong, you blow up the receiver, fun for people watching, not so much for the equipment owner. Even if you get the timing right, you cannot transmit and receive at the same time. Of course an obvious solution is to have two antennas, but soon you'll discover that when you're transmitting and receiving on the same frequency, even using two antennas, you'll have the exact same issues. It's why the local 10m repeater here in Perth, VK6RHF, has the transmitter in one location and a receiver 12 km away, connected to each other via a 70cm radio link. Other solutions in this space are cavity filters, duplexers and diplexers. These all require that the transmit and receive frequencies are different and the equipment is generally tuned to a specific pair of frequencies. Physically cavity filters can be massive, not to mention fragile. So, solving the issue of having a transmitter and receiver together on the same frequency is one that is challenging to say the least. It's a common issue, think about mobile phones, satellites, broadcast transmitters, and even your own amateur radio station. An RF circulator is a device that solves this in an extremely elegant way. For starters, it's a passive device, which means that you don't need to power it, there's no moving parts, no switches, no delays, no external controls, it's a box, generally with three sockets or ports, though versions exist with more. At a basic level, it works like this. A signal inserted into port one, will only come out of port two. Similarly, a signal into port two, will only come out...

Foundations of Amateur Radio The other day I received an email from Frank K4FMH asking me about an idea I'd worked on some time ago, namely the notion that I might monitor solar flux at home using a software defined radio. At the time I was attempting to get some software running on my PlutoSDR and got nowhere fast. Before I continue, a PlutoSDR, or more formally an ADALM Pluto Active Learning Module by Analog Devices, is both a computer and a software defined radio receiver and transmitter in a cute little blue box. I've talked about this device before. It's an open design, which means that both the software and hardware are documented and available straight from the manufacturer. Out of the box it covers 325 MHz to 3.8 GHz. You can connect to a PlutoSDR using USB or via the network, wireless or Ethernet, though I will mention that neither of those last two is currently working for me, but more on that later. Encouraged by Frank's email, I set out to explore further and came across a 2019 European GNU Radio days workshop, which discussed some of the tools that are available for the PlutoSDR, accompanied by two PDF documents walking you through the experience. One comment around why the PlutoSDR uses networking as one of the connectivity options spoke to me. From a usability perspective, networking makes it easier to access the PlutoSDR from a virtual machine, since most of the time that already has network connectivity, whereas USB often requires drivers. As you might recall, network connectivity is one of the many things that I'm trying to achieve with a project that I'm calling Bald Yak, since by the time we're done, there's not going to be much hair left from all the Yak Shaving. The Bald Yak project aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio. As a result, I set about trying to actually walk myself through those PDF tutorials .. and got stuck on the first sentence on the first page, which helpfully states: "The necessary prerequisites have been installed on the local lab machine." It went on to supply a link to a page with instructions on how to acquire those very same prerequisites. Two days later, after much trial and error, I can now report that I too have these installed and because I cannot help myself, I made it into a Docker container and published this on my VK6FLAB GitHub page. To put it mildly, there's a few moving parts and plenty of gotchas. As an aside, if you think that installing Docker is harder than installing these tools, I have some news for you .. trust me .. by a long shot .. it's not. Right now I'm working on writing the documentation that accompanies this project such that you can actually use it without needing to bang your head against the desk in frustration. Mind you, the documentation part of this is non-trivial. For reasons I don't yet understand, my Pluto does not want to talk to the network directly over either WiFi or Ethernet, and connecting over USB through a virtual machine inside a Docker container is giving me headaches, so right now I'm connected across the network to a Raspberry Pi that's physically connected to the Pluto. As a result, I can now use the tools inside my Docker container, connected to the Pluto through the Pi and if you're curious, 'iiod' is the tool to make that happen .. more documentation. At this point you might well ask, why bother? This is a fair question. Let me see if I can give you an answer that will satisfy. Monitoring solar flux typically occurs at 2.8 GHz, which is outside the range of RTL-SDR dongles which top out at about 1.7 GHz. For the PlutoSDR however, it's almost perfectly within the standard frequency range. One of the tools that is introduced by the talk is an application called 'iio-scope', which as the name suggests, is an oscilloscope for 'iio' or Industrial I/O devices, of which the PlutoSDR is one. As an aside, the accelerometer in your laptop, the...

Foundations of Amateur Radio The other day I went on my first POTA or Parks On The Air adventure, this time I was on my own. If you recall, my power company announced yet another planned network outage and I felt that I could use this time without electricity to my benefit, for a change. As is traditional, I did all the prior planning to prevent pretty poor performance. I made a list, checked that all the items on the list were in my kit, packed the kit days before, put it all ready to go in the hallway the night before, packed the car on the day and set out on my adventure. I will confess that I was slightly more sweaty than anticipated when I set off because the umbrella in the boot of my car has a nasty and recurring habit of getting in the way, specifically it stops things from getting pushed right to the full depth of the boot. Mind you, it wasn't until I started getting agitated that I realised that it wasn't the umbrella's fault entirely this time, since as it turns out, the folding chair that I was attempting to jam in place doesn't actually fit longways into the boot. Anyhoo, I set off and visited the local petrol station. I was not prepared for a customer to spend 15 minutes dribbling the last bit of diesel into their pretend Sports Utility Vehicle, but he looked like he was up for a fight, so I smiled sweetly and waited for him to pay and move his box on wheels. After paying for my own fuel and driving off, the pressure in my bladder had gotten beyond the "cross your legs and hope for the best" stages and I swiftly made my way to the nearest shopping complex where a local pharmacist helpfully told me that there were no toilets in the building and that the local hotel or fast food joint were the place to relieve the pressure. One problem .. they were both closed. At this point I was in pain, and discovered that I couldn't read the screen on my mobile phone in the lovely sunlight, because it was set to battery saving mode, since my charger was at home where the power was out. After disabling the battery saving mode I opened the local public toilet map shortcut on my phone, and discovered that fortunately the shortcut still worked, opening up my default browser, which suddenly didn't want to display a map. Copied the URL to another browser, still in pain, finally a map. Click on the nearest icon and it navigates me there from Darwin, or over 4,000 km from where I actually am. Luckily it has the GPS location which I copy and then paste into my mapping app, and I can finally navigate to the nearest toilet. Several comment worthy navigation moves later, I drive into the car park, lock the car, painfully shuffle to the building, do my business in the very clean facilities and then decide that I should just stop, sit, and take a breath. So, I get in the car and discover that my partner was right when they heaped scorn on our newly acquired thermos cup. It really does hurt your nose when you try to drink from it and the sharp edges in your mouth do nothing to make the experience joyful. Meanwhile there's some trucks moving around in the car park and a guy walks up to the car to ask me if I can move because they want to move a third, or was it forth, truck into the space. I swallow my sip of restorative coffee, wipe the now wet bridge of my nose, and move the car, only to be blocked from leaving the exit thanks to the slowest reversing truck I've ever encountered, one who then proceeds to sit at the next intersection for five minutes without indicating where it was going. Are we having fun yet? I finally made my way to the main road where I attempt to calm my nerves with the help of a Morse code edition of my podcast. It's been the only exposure I've had to Morse for way too long. This accompanies me to my first destination, breakfast. I'm going to skip past the drivers in the centre lane driving at 10 km per hour below the posted speed limit, or the ones who think that jumping out of a side street in front of...

Foundations of Amateur Radio Recently my local power company notified me of a planned network outage, that's code for, we're turning off the power and your choice is to deal with it. If you've been paying attention, you'll note that this is not the first time this has happened in recent times. On this occasion I want to make a difference and actually use the day wisely. Coincidentally, the 750th instalment of F-troop is coming up and traditionally we try to find an excuse to get outside and set-up a station in a local park somewhere. If you recall, I recently went outside and came across a new park, one with picnic tables, gazebos, toilets and all the mod cons required for a party. Combine these unrelated events and you end up with testing the idea of running F-troop, a weekly net for new and returning amateurs, from this park, which also neatly turns that into a POTA or Parks On The Air activity, which raises several logistical questions. The first one being, what is the radio noise like in this park, followed shortly by the question, can I hit my local 2m repeater, any 2m repeater, or the local 10m repeater? If the answer to those questions is unsatisfactory, I might be required to rethink my plans. Combining those questions with a power outage at home seems like the perfect excuse to go out into the bright day to get on air and make some noise. One challenge. Having removed my radio from my car several years ago to accommodate the replacement of the transmission, I never did replace it and never used my radio in the car again, which truth be told is not a situation I ever imagined when I first installed it many years ago. This leads me to creating a list, which should come as no surprise, a list with what I need to bring as a minimum requirement to test the questions I need answers to. I will confess that the "making a radio packing list" skill-set has atrophied in recent times, so I started small. I'll need a radio, and a suitable antenna, in my case, at least two, one for 2m and one for 10m. Then there's the question of power, at which point I discovered that my trusty portable sealed lead acid batteries have finally died, not bad after 15 years, well, 12 years of regular use. Likely they would have continued to be of service if I'd used them in the past three years, mainly hampered by the death of my 12 volt battery charger. If you feel like I'm going off track, you'd be right. That was the exact experience I had when I started building my list. I added a digital multimeter, an antenna analyser, an antenna tuner and coax, then realised that I needed to check if the coax adaptors were the right ones and so it continued. The upshot is a preliminary list with 15 items on it, in various stages of fully populated, for example, I know I have a 2m and 70cm antenna in the garage, but I haven't touched it in years, so I need to go find it, and the battery in my digital multimeter needs checking, you get the idea. It's a good thing I started this caper well over a week before the planned outage, so at least I have half a fighting chance to get it to the point of usefulness before my screen turns black due to the threatened lack of electricity. It occurred to me whilst I was in the middle of this extended list creation process, that I was essentially replicating what I might have experienced the very first time I went outside with my station in 2011. In coming to that realisation, the stress levels that were building steadily at that point, pretty much dissipated with the understanding that I'd already done this and survived the experience. In other words, there was nothing worth stressing about. So, this leaves me with a question for you. What does this process look like for you, how do you prepare to get on-air and make noise, what steps do you take and what do you avoid, are there things you might share with a new amateur and if so, how will you do that? I contemplated sharing the list in a public place, but...

Foundations of Amateur Radio The pursuit of amateur radio is a glorious thing. On the face of it you're forgiven if you think of it as a purely technical endeavour. Far be it for me to dissuade you from that notion, but permit me to expand into other areas that rarely get a mention when we discuss this amazing hobby. It's the place where you go to communicate with other people, who live a different life, doing the things that they enjoy. It's also the place for finding an excuse to go outside and set-up your station on the side of a mountain, or a park, a museum or a lighthouse. Then there's the joy of finding new friends who introduce you to other aspects of life, super computing, the medical field, tow truck driving, radio astronomy and electronics, to name a few. While I was the first person in my school to save up their summer job earnings to buy their own computer, a Commodore VIC-20, I never did come across this. "It is pitch black. You are likely to be eaten by a grue." is a phrase that might mean something to you, or not. To set the stage, it's the 1960's, you're a science fiction author and you need a ravenous predator. With origins in Danish and Norwegian, "grue", from gruesome, seemed to fit the bill for Jack Vance while was writing his Dying Earth series, mind you, Robert Louis Stevenson used it in 1916 in a short story called "The Waif Woman", writing "and a grue took hold upon her flesh", which is more gruesome than predator. Flash forward to 1977, you're writing an adventure game for a PDP-10 mainframe computer whilst, let's call it studying, at MIT, and you need a way to stop people wandering off the map, and so the text adventure game "Zork" got its famous phrase. I'm mentioning this because I wondered if anyone had used their love for Zork as an excuse to set-up a server on HF radio that you could play with. I'll confess that I spent way too many hours looking at this and it appears that you can use the software "direwolf" as a way to get packet radio to work across amateur radio without needing anything more than a radio and a computer with a sound-card. There's even an article by Rick Osgood titled: "How to Setup a Raspberry Pi Packet Radio Node with Zork", though I will mention that it relies on hardware to connect to a radio, rather than use "direwolf". There's a few moving parts, but it looks like this is totally doable, there's already Docker containers for both Zork and direwolf, even a container called "packet-zork", and a multi-user version called "MultiZork", so how hard can it be? I jest. As an aside, because I'm a geek and I can, there's a common misconception that a Docker container is equivalent to a virtual machine. For lots of reasons, that's not true. A better way is to think of it as a security wrapper around an untrusted application. Speaking of untrusted, while we're all essentially bipedal lifeforms with a similar set of attributes, on a daily basis we seem to discover more and more reasons to find fault or demonise differences. Contrast this within the global community of radio amateurs, where we have this "weird" activity that we all seem to share. I think that the most under-reported, perhaps even undervalued aspect of our hobby is that it's an excuse to talk to someone else. It's like a force of attraction, the glue, the one starting point that you know another amateur has in common with you. So, next time you venture outside, either in real life, or virtually, consider, at least for a moment, that there are other radio amateurs among us, also having fun. I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I came across an article written by programmer, artist, and game designer "blinry" with the intriguing title: "Fifty Things you can do with a Software Defined Radio". Documenting a weeks' worth of joyous wandering through the radio spectrum it explains in readily accessible terms how they used an RTL-SDR dongle to explore the myriad radio transmissions that surround us all day and every day. As you might know, I've been a radio amateur since 2010 and I must confess, even with all the things I've done and documented here, there's plenty in this adventure guide that I've yet to attempt. For example, when was the last time you decoded the various sub-carriers in an FM broadcast signal, including the pilot tone, the stereo signal, station meta and road traffic information? Have you ever decoded the 433 MHz sensor signals that your neighbours might have installed, weather, security and other gadgets? Or decoded shipping data, transmitted using AIS, or Automatic Identification System, and for context, we're only up to item 12 on the list. One of the biggest takeaways for me was that this is something that is accessible to anyone, and is a family friendly introduction to the world of radio that amateurs already know and love. The article touches on various applications that you might use to explore the highways and byways of the radio spectrum, including SDR++, SDRangel, WSJT-X, QSSTV, and even mentions GNU Radio. With enough detail to whet the appetite, I learned that SDRangel, developed by Edouard F4EXB and 70 other contributors, has all manner of interesting decoders built-in, like ADS-B, Stereo FM, RDS, DAB, AIS, weather balloon telemetry, APRS, even VOR. As it happens, you don't even need to install SDRangel to get going. Head on over to sdrangel.org and click on "websdr" and it'll launch right in your browser. Once you're up and running, you can use your RTL-SDR dongle to start your own small step into the wide world of radio, amateur or not. Sadly the PlutoSDR does not work on the experimental web version, so I had to install SDRangel locally. That said, I did get it to run and connect to my PlutoSDR which worked out of the box. The user tutorial is online and the Quick-Start walks you through the process of getting the software installed and running. One thing that eluded me for way too long is the notion of channel decoders. Essentially you configure the receiver, in my case a PlutoSDR, and start it running. You'll be able to change frequency and see the waterfall display, but nothing else happens, and there's no obvious AM, FM or other mode buttons you'd find on a traditional radio. Instead, you'll need to add a channel decoder, cunningly disguised as a triangle with circles at the corners with a little plus symbol at the top. You'll find it immediately to the left of your device name. When you click it, you're presented with a list of channel decoders, which you can add to the work space. This will do the work of actually decoding the signal that's coming into the software. SDRangel also supports M17, FreeDV, RTTY, FT8 and plenty of other amateur modes, and includes the ability to transmit. Oh, did I mention, it can also connect to remote kiwisdr receivers? I have to say, it's a joy to see software that I've previously looked at and admittedly shied away from, actually doing something with the radio spectrum around me. I will confess that SDRangel has a lot of moving parts and it's like sendmail, user friendly, just picky whom it makes friends with. So, time to dig in, play around and bring it to the next amateur radio field day "Show and Tell" and share with the general public just how interesting the radio spectrum around us can be. I'm going to work my way through the 50 items, just for giggles. What are you waiting for? I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I went for a walk, I know, shock-horror, outside, daylight, nature, the whole thing, in a local national park, for the first time in too many years. Almost immediately I noticed that this would be an excellent location for an activation. If you're not familiar, it's an amateur radio excuse to set-up a portable station in a new location, in this case, potentially something called POTA, or Parks On The Air, but you don't need to find a formal activity with rules to get on air and make noise. I commented on how easily accessible it was, that it had picnic tables, gazebos for shelter, nearby toilets, free BBQs, ample parking, lots of open space, and no overhead power lines. I saw one solar panel on a pole and no evidence of any other electrical noise sources. It wasn't until later that I realised the act of noticing this, in that way, with those details, is not something I would have done before becoming a radio amateur. I'd have looked at the same location, considered its beauty and serenity and perhaps in passing considered that we could have a family gathering, or a place to come back to when I wanted some peace and quiet, or a place where I might have a BBQ with friends. Not that those things went away, just that I noticed other things, now that I'm an amateur. It made me consider just how much this hobby has irrevocably changed me. I know I've mentioned this before, since becoming an amateur I cannot walk down the street without noticing TV antennas pointing in the wrong direction, but this change in me is not limited to that. Now I cannot help discussing the best place to put a Wi-Fi base station in a building, or thinking about and checking on solar activity, wondering about battery capacity, RF interference, trees to potentially use as sky-hooks for wire antennas, power company substations, pole-top transformers, random weird and wonderful antennas and probably more. The point being that this hobby opens the door to a whole new way of looking at the world and I don't think I've overstated, if I say that amateur radio has literally changed my world view. In considering this, I suspect that it's related to a cognitive bias known as the Frequency Illusion, where you notice a specific concept, word or product more often after becoming aware of it. You might for example have experienced this with the brand or model of radio you use and suddenly discovered that there's lots of other amateurs talking about that particular piece of equipment. I've seen this with recurring topics during the past fourteen years of the weekly F-troop net. For example, every couple of years someone discovers magnetic loop antennas and starts talking about how they've built or bought one. The conversation inevitably goes past variable capacitors, through air variable capacitors, on to vacuum variable capacitors and then the conversation generally stops. While it's happening, multiple people come on the same journey, only to follow the exact same path. Several years later, the cycle repeats. Don't misunderstand, I welcome the discussion, point people at relevant resources and help them on this journey. I'm commenting on the recurrence of the journey, not the nature of it because it's easy to take this example and hold it up as "there's nothing new in this hobby", but nothing could be further from the truth. In my opinion, the level of complexity associated with radio communications is infinite and anyone, including you and I, can contribute to the discovery associated with it. So .. what things have you noticed that were caused by this somewhat eccentric hobby and perhaps the phenomenon of Frequency Illusion? I'm Onno VK6FLAB

Foundations of Amateur Radio I've owned a Yaesu FT-857d radio since becoming an amateur and at the time I was absolutely blown away by how much radio fits inside the box. It's smaller than most of the commercial radios I'd seen when I bought it. I came across a video by Michael KB9VBR, the other day showcasing a wooden cigar box with a complete, well, almost complete POTA, or Parks On The Air, activation kit. I say almost, since Dave KZ9V, the owner of the kit, points out that the box doesn't contain an antenna. It made me wonder how small is small? According to RigPix, the lightest transmitter on an amateur band, in this case, the 5 GHz or 5cm band, is an Amateur TV transmitter. Weighing in at 3.9 grams. The Eachine TX-06 is capable of FM with about 18 MHz of bandwidth with an audio sub-carrier. Of course, that's not a transceiver, but I thought it worth mentioning in case you needed an excuse for something tiny in your shack, besides, as far as I can tell, there's never too much Amateur TV in the world. I've built a crystal radio on a breadboard which is tiny, but it doesn't transmit, so to set the stage, I think we need to limit ourselves to transceivers, that is, a device capable of both transmitting and receiving, on amateur bands. Before continuing I'd like to express my thanks to Janne SM0OFV, for the rigpix.com database that he's been maintaining, in notepad, since 2000. Without the invaluable information documented for the currently 7,512 radios, I'd be spending an awful lot of time hunting for information. Moving on, the FaradayRF board is a transceiver, capable of using 900 MHz or the 33cm band. It comes in at 30 grams, but without a computer it's a circuit board with potential. The PicoAPRS by Taner DB1NTO, is a 2m transceiver specifically for APRS, weighs in at 52 grams and similar in look and a third of the weight of an Ericsson T18 mobile phone. Speaking of mobile phones, the PicoAPRS does WiFi and Bluetooth, can pair with your phone and act as an AX.25 modem. I'll confess, I'm drooling. Moving right along, for 70cm there's a Rubicson Walk 'n' talk, weighs in at 65 grams. Mind you, the RigPix database puts this under the "License-free / PMR446" section which comes with a sage warning, check your local laws before transmitting. There's a few Alinco DJ-C models for different markets that operate on 2m or 70cm, weighing in at 75 grams. The ADALM Pluto weighs 114 grams, but you'll need a USB power supply of some sort to make it do anything. It can operate between 70 MHz and 6 GHz, but the user interface is limited to a single button and LED, so if you want to interact with it, you'll need some external technology. Moving on to HF transceivers, weighing in at 199 grams, without the bag, but all the options, is the Elecraft KH1. Transmits on 40m, 30m, 20m, 17m and 15m and receives between 6 and 22 MHz. It's CW only, but you can receive SSB. If CW isn't your thing, RTTY and PSK can be used on the 40m band with a Silent System Handy PSK 40. Presumably the Handy PSK 20 runs on 20m. Both weigh in at 250 grams. The Zettl P-20xx SSB does SSB, AM, FM and CW, transmits on 10m, 11m, 12m and 15m as well as the MARS frequencies and receives between 14 and 30 MHz, weighs 300 grams. Even comes with CTCSS. Another Elecraft model, the KX2 weighs in at 370 grams, does 80m to 10m and the WARC bands, does SSB, CW and data. Mind you, you'll also need to add the weight for the microphone and paddles, and factor in a computer if you want to do more than PSK and RTTY. The Expert Electronics SunSDR2 QRP does 160m to 10m, the WARC bands and 6m. Weighs in at 500 grams, has a network port and two independent receivers. Operates at 5 Watts. There's no user interface, unless you count the reset and power buttons, so I'm not sure if it can operate on any mode with just a microphone, but given the "Depending on software" disclaimers throughout, I'm going to guess you'll need to bring a computer to make it sing. The Risen...

Foundations of Amateur Radio Over the past nine months or so I've been working on a project that I've called Bald Yak. If you're unfamiliar, the Bald Yak project aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio. One of the, admittedly many, challenges I've set myself is getting data from a radio receiver into GNU Radio across the network, preferably the Internet. Today I can report a small step in the right direction and frankly I can't contain my excitement. Now, I need to acknowledge that I'm geeking out here. It's hard to contain excitement when you find something that seems to speak your language. It also means that I realise that I run the very real risk that I'm going to lose you before you get to why this is a milestone, so let's put that up front before I explain why. To whet your appetite, yes, you can access a KiwiSDR across the Internet and record raw data from it and control the process externally. This is a very big chunk of the problem I've been working on and turns out to actually be live and ready to play with. Fair warning this is technical, there are moving parts. I'll do my best to explain, but if I miss any, feel free to get in touch, you have my address, cq@vk6flab.com. In passing, recently I made mention of the KiwiSDR community and tools that could potentially allow access to a remote receiver, although at the time I pointed out that I wasn't sure if the tools I found could access remote receivers, or if they were intended to access hardware locally. KiwiSDR is one of a group of so-called Web SDR tools. Essentially a website where you can access a remote receiver and tune to the radio signals it can hear. SDR, or software defined radio, is a way to convert incoming antenna signals into the digital realm where computers, and in this case, the Internet, live. Turns out that a tool called "KiwiClient" takes a hostname and a port as a parameter, so much so that the in-built help shows this as the first example. What this means is that you can essentially run a copy of KiwiClient on your own computer and use it to access a KiwiSDR across the Internet. The first commit was on the 8th of May 2017 and thanks to the efforts of about 14 developers, KiwiClient is the software equivalent of a KiwiSDR multi-tool. This is exciting all by itself, but this gets better. You can specify more than one server. This means that you can record two, or more, signals from across the globe, and capture these simultaneously. You can set the decode mode, which I immediately used to tune to a local broadcast station and recorded it from two different receivers across the Internet, allowing me to not only compare the difference in delay between the signals, but also the reception differences. It's fascinating to hear the same station from two receivers, one in each ear, all manner of different propagation artefacts become apparent. Then I got a little more adventurous and discovered that one of the supported modes is I/Q, which means that I can, and did, download raw sample data across the network, which can then be used within GNU Radio. This is important because the aim for Bald Yak is to process the signals separately from the receiver. It gets better. There is a radio fax receiver that automatically saves pages as they are processed, something that you could use to access weather fax services. Then there's a tool you can link to "WSJT-X", which you might recall is an application that can decode weak signals. Not only that, the tool supports "fldigi", a digital radio mode application. Both those applications can control the radio using Hamlib rigctl, which means that KiwiClient supports changing frequencies of the receiver, across the Internet, though truth be told, I haven't yet tested that .. my available computing resources are still strictly limited. Oh, the software also has the ability to record waterfalls, do scanning, and provides tools...

Foundations of Amateur Radio The other day I stumbled on a random post by Gary N8DMT which caused me to view the world in a different way. The post outlined combining a PlutoSDR and an application called SATSAGEN to measure the frequency characteristics of a coupler. Aside from a detailed description, the post includes a couple of excellent photos showing the PlutoSDR connected to the coupler and the output piped back into the Pluto. Before I continue, a PlutoSDR is a Software Defined Radio or SDR, officially it's called the ADALM Pluto Software Defined Radio Active Learning Module. It's essentially a full-duplex radio and computer in a box. It runs Linux and connects to the world via USB, and of course radio, unofficially between 70 MHz and 6 GHz. I've talked about this device before. When I say full-duplex, I mean that it can transmit and receive at the same time. Gary's post triggered something unexpected in me. The notion that you could use two patch leads, one connected to the transmitter, the other connected to the receiver, joined together by a device that you might want to test. It immediately reminded me of another device that was given to me, a NanoVNA, a device that's specifically designed to measure things like impedance, frequency response, generate Smith charts and all manner of other characteristics. Not only that, it also reminded me of another device, a TinySA, specifically designed to analyse spectrum and to generate signals. Both the NanoVNA and TinySA are lovely tools, but in looking at the post it suddenly occurred to me that their functionality, at least superficially, appears to mirror the PlutoSDR, in that you can create a signal and then measure that signal. Turns out that I'm not the first to make this observation. For example, the YouTube channel "From Concept To Circuit" goes through the process of describing precisely the concepts behind both a spectrum analyser and a network analyser while showing the programming code in Python. The channel also provides that code in a GitHub repository, which includes several other very interesting examples, like a beamforming transmitter as well as a beamforming receiver, also covered on YouTube. Another example is a tool I already mentioned, SATSAGEN, by Alberto IU1KVL, which implements a wideband spectrum analyser. Although it's Windows only, Alberto includes information on how to run it using Wine under Linux and MacOS. As a bonus, SATSAGEN in addition to the PlutoSDR, also supports RTL-SDR dongles, HackRF, USRP, RSP1, AirSpy, and many others. If text is more your thing, "retrogram-plutosdr", shows a spectrogram in your terminal window. Check out the "r4d10n" GitHub repository belonging to Rakesh VU3RGP, who says that the "retrogram" project is "hacked from" the "RX ASCII Art DFT" example, which you can find on the Ettus Research GitHub repository. One thing to consider is that the various GitHub repositories I've pointed at, will give you access to the moving parts of how all this works. I will mention that my favourite tool in this space continues to be GNU Radio, but I understand that you might not want to roll your own tool from parts. That said, rolling your own is in my experience a great way to discover precisely what you don't know and to come away learning more, but then, that's just me. Regardless of your chosen tool, I think the takeaway should be that when you try something new, even if it's only new to you, the idea of writing down what you discovered and sharing it, is a fantastic way to grow our community. Remember, just because something is old hat to you, doesn't mean that it is to the person you share it with. Besides, based on the current global birth rate, there's at least a thousand babies born during the past four minutes, some of whom will become radio amateurs, so, share. Said differently, if you come across a person who has never heard of the "Diet Coke and Mentos" thing, it's your job to immediately drag them to the...

Foundations of Amateur Radio Recently I discussed the idea of listening to the radio spectrum across the internet for the purposes of getting signal into your shack when radios, or in my case, antennas are causing you challenges. I continued to explore and discovered a project by Jacobo EA1ITI, called "radioreceiver". Behind that unassuming name lies a tool born in 2014, that allows you to plug an RTL-SDR dongle into your computer, open up your web-browser, and listen to the radio signals that your dongle can receive. In case you're unfamiliar, an RTL-SDR dongle is a small USB device, looks a lot like a USB thumb drive, jump drive, data stick or flash drive, basically a hunk of plastic with a USB connector on it. An RTL-SDR dongle generally also has some form of antenna connector. It's typically sold as a digital radio and digital television receiver, but websites like rtl-sdr.com sell purpose built ones. They can be found starting at about $15. I realise that this is using a local receiver, with a local antenna, but it's inside a web browser, which is half of what I expected. When you hit the play button in the bottom of the screen, you'll be prompted by your web browser to give permission to access your RTL-SDR dongle and the fun starts. You'll see a live waterfall, hear audio, and have the ability to tune to any frequency you can reach. Depending on your dongle, typically somewhere between 500 kHz and 1.76 GHz. The application consists of seven files, a total of 352 kilobytes that you can store on any web server and run, with one caveat, in order for your web browser to talk to your dongle, it needs to be served using HTTPS. Jacobo has set-up radio.ea1iti.es and I've set-up sdr.vk6flab.com, both showing the same tool. You'll find the code on my VK6FLAB GitHub repository, and of course on Jacobo's. There are some things you need to know. You will need to use a web browser that supports WebUSB, currently that's Chrome, Edge, Opera and several others, sorry, Safari and Firefox don't .. perhaps it's time to talk to Apple and Mozilla. All is explained if you click on the little question mark at the bottom of the screen, it will even tell you if the browser you're using to read the help is compatible or not. If you have an Android phone, you can run this tool too, although you will need to find a way to connect your dongle to your phone. I'm currently limited in my ability to test this and you may need to install some drivers on Windows and Linux, but MacOS and presumably Android, works out of the box. The software also supports offline operation, so you can load it as a Progressive Web App, or PWA, and use it in the field away from the internet. Did I mention that all the decoding is happening inside the web browser, so you can see which code is doing what .. and before you ask, yes, it's minimised in the browser, which you can make into human readable code, but when you look at the source, it shows precisely what is happening, all written in Node.js, TypeScript and JavaScript. It supports CW, SSB, AM, Narrow and Wideband FM and decodes stereo, something which none of my amateur radios do. You might be able to tell that I'm excited. It's because this is providing the basic functionality of a radio inside a web browser, and I didn't need to install it to get started. On the Macintosh I tested this on, I literally opened the web page, plugged in a dongle and hit play. Just so we're clear, just because this is using a web page on a web server, you accessing it will only give you access to your radio not mine. This of course opens the doors to all manner of other fun stuff which I'm expecting to play with for the next little while, and yes, this is also Bald Yak adjacent, I'm aware. In the meantime, you can play with this right now, sdr.vk6flab.com is the place to go. Word of warning, it's addictive and easy to forget it's a radio with an antenna plugged into your computer, so take precautions when electrical storms are...

Foundations of Amateur Radio One of the many challenges associated with being a radio amateur is actually being able to listen to weak signals. If you're like me and more than half the planet, you live in an urban area, which comes with the benefits and pitfalls of having neighbours. From a radio perspective, there's plenty of noise that drowns out weak signals, so more and more amateurs are finding new and interesting ways to deal with this. Over the years I've talked plenty about so-called web-sdr, or internet accessible software defined radios. Essentially a radio receiver, preferably in a radio quiet area, hooked up to some software that allows you to listen in using a web browser. There's thousands of internet based services across the globe, the most popular of those are websdr.org and kiwisdr.com. As a new amateur you might have visited one or more of these and tuned around to listen to various radio stations and QSOs or contacts between amateurs, on bands that you can't access because you don't have the gear, or frequencies that are drowned out locally by your neighbour's pool pump, air conditioner, LED lighting, solar power inverter, television, motor home, cycle, or whatever else they seem to have an endless supply of behind closed doors. As a crusty amateur, and after about 15 years, I'm probably one of those, you might have started experimenting with building your own, or you might be blissfully unaware of these internet marvels. Either way, one restriction you run into is the ability to do anything other than listen. You might get the option to pick between Upper and Lower Side Band, or AM, sometimes even FM, but generally that's your lot. This means that trying to use such a tool to decode WSPR, or FT8, or RTTY, CW, PSK31, or whatever else takes your fancy becomes a challenge. It occurred to me that if you're able to capture the raw signal from a web browser, you could feed that into your decoder of choice. It would also mean that you wouldn't need any local hardware to start playing. Before you get all hot and bothered like I did. This is a non-trivial process that several others have attempted to wade through with varying levels of success. Much of the documentation I've discovered revolves around virtual audio cables and loop back software, and even the idea that you physically plug your computer's speaker output into your line input, or even hold a microphone up to your speakers. Aside from the lack of elegance associated with such contraptions, they require that you install all manner of weird software, and in many cases deal with permissions, since microphones are generally locked for good privacy reasons. Prompted by the webserial tool by Phil VK7JJ, it occurred to me that if we can talk to actual physical hardware within a web browser, then we can probably use a web browser as an audio source for local decoding software. Before you start hunting for the source code, there is none. I've spent the past few days playing around and although I made a waterfall display inside GNU Radio that used the audio from websdr.org, the results were not amazing, and I created a proof of concept by using a tool called BlackHole on the Macintosh I was using at the time. It's essentially doing shenanigans with audio mapping, not something which I really want to do, but it gives me a pretty picture, or not, as the case may be. More interesting is the progress being made over in the KiwiSDR community, where there is already an I/Q button, in other words, the raw data needed for processing further down the line. I came across projects that link the KiwiSDR to other tools, but it's unclear if that's the hardware, or the web client, I suspect it's the hardware, but I might be mistaken. If you're not sure what this might mean, think about listening to the same frequency at the same time across the globe using multiple web browser tabs, and comparing the signals in real time, or decoding them, or using them for...

Foundations of Amateur Radio Every single radio amateur has come to this hobby with an itch to scratch. Time and again I've seen amateurs around me pursue that particular purpose, only to come out the other end with a look of bewilderment writ large across their face. For some amateurs it means the end of their involvement in the hobby, for others it starts a new journey into the unknown. One of the ways we explore our community is by travelling out of our shack into the big outdoors in whatever form that takes. Popular activities include setting up a radio in a location and talking to others, known colloquially as an "activation". We do this all over the planet. Perhaps the most recognisable of these is IOTA, or Islands On The Air, where a station is erected on an island and contacts are made. As amateurs we cannot help ourselves and seem to have an insatiable need to measure our prowess. We do this by counting how many contacts, callsigns, countries, grid-squares, or in this case, islands, we've managed to put in the log. If an island represents a new callsign, a new country, and a new grid-square, the contact making will turn into a feeding frenzy that can last for days, especially if the station offers multiple bands and modes, making the effort all the more tempting. We don't stop with islands. Summits, with Summits On The Air or SOTA are popular, as are Parks, POTA, and even over a weekend, the International Lighthouse and Lightship Weekend, or ILLW. Some of these activations follow rules set out by amateurs like you and I, who thought it would be fun to track such activations and encourage others to participate. For example IOTA World publishes a four page document outlining what's required for those on the island, activators, and those trying to make contact, or chasers. This raises an important point. Rules require documentation, which leads to discussion and disagreement, and versions. I can show you two versions of the IOTA World rules, neither is dated, of course both are different, so if you're going to publish rules, make sure you add a date or version, preferably both, to the rules document. Disagreements aside, sometimes there are multiple programs with the same name or aims. Two groups came up with the same idea and didn't know about each other, or, a group in a different country wanted to run the show in a different way and a new group was formed. I'm mentioning this because sometimes these groups are antagonistic towards each other and have forgotten that the whole point of this is to have fun. So, what else can we activate? Well, there's Castles and Stately Homes, Bunkers, Beaches, Museums, Walmart Parking Lots and even Toilets On The Air, mind you, Slow Scan Television, or SSTV is discouraged as a mode. The other day the power was off for maintenance in my street and I planned on escaping to the local library, which caused me to search for libraries across Perth. It seems there's pretty much one in every suburb and I considered the notion of activating a library or three, comes with easy access to public transport, a car park, and even toilet facilities, what's not to like? I wondered what might be a suitable exchange so it could incorporate the library itself, promoting amateur radio and libraries, two birds and all. I made a comment on mastodon.radio and it turns out that Frank K4FMH beat me to it, several years ago. Libraries On The Air, or LiOTA. I've been hunting for a dataset of libraries in Australia to give to Frank, but it's been slim pickings, despite there being over 10,000 of them, apparently around 10% of those public. It raises another question, is there a directory of activation types anywhere? I couldn't find one, so I started a list on my GitHub repository. Feel free to add any I missed. Toilet jokes aside, consider that TOTA is being held during the annual Hackers On Planet Earth conference and it will introduce new people to our amateur community, which ultimately might be...

Foundations of Amateur Radio Recently I came across a series of strident posts about the injustice associated with a non-amateur service using the 70cm band. Complete with links to discussions, spectrum plots, angst and even incoherent outrage, all related to the notion that whomever "allowed" this user to transmit on this band was clearly incompetent. Except, that this is probably not the case, or the full story. So, what's going on and why are people incensed? This all started at least six years ago. Since then AST SpaceMobile has deployed seven low Earth orbit satellites and used the 70cm band to communicate with them. Although in the trial phase, there's plans for an additional 243 satellites, and there's at least one other company playing in the same space, Atmos Space Cargo. The outcry from amateurs is around the commercial use of "their" 70cm amateur band. It's an emotional statement, but what is the reality? Before I dig in, let's set some terms. Radio frequencies are globally coordinated because electromagnetism doesn't care about sovereign borders. This coordination is conducted at the United Nations by a body called the ITU, the International Telecommunications Union. Within that body, amateur radio gets a seat at the table from an organisation called the IARU, the International Amateur Radio Union. For the purposes of the ITU, the world is divided into three, Region 1, or essentially Europe, Russia and Africa, Region 2, the Americas and Greenland, and Region 3, the rest of the world. There's more to it, for example, Antarctica is split across all three, but for the moment, that really doesn't matter. Of interest is that the band plan, the agreements that outline which frequencies are set aside for what service, might be defined differently across each of those three regions. To add complexity, each country can be granted exceptions. I don't know the exact mechanics of how this is achieved, but I can guarantee that there's lots of haggling and foot stomping, diplomatically of course. If you're curious how I come to that observation, just look at the absurd list of exceptions associated with each band plan allocation. Further complexity is added by the fact that not all allocations occupy the same frequency range. For example, in Region 1, the 2m band for Amateurs exists between 144 and 146 MHz, in Region 2 and 3 it's between 144 and 148 MHz. Within an allocation there is the concept of shared and exclusive priorities. These determine who "wins" if two stations with a different service are transmitting on the same frequency. Essentially, a secondary user may not interfere with a primary user and a tertiary user may not interfere with either a secondary or a primary user and so on. A primary user can pretty much do what they want, as long as they stay within the allocation and don't interfere with other primary users. As a result, the order in which services are listed, matters. An exclusive allocation doesn't have to be shared at all. Between regions these service priorities might not be the same. For example, in Region 1 between 430 and 432 MHz is allocated to Amateurs and Radio Location, but in Region 2 and 3 it's between Radio Location and Amateurs. So an amateur using that frequency whilst in Region 1 would be a primary user, but in Region 2 or 3 they wouldn't. As an added wrinkle, for example in Australia, that slice is "primarily for the purposes of defence and national security", even though Radio Location is the primary service and Amateurs the secondary one. As a bonus, amateurs in Australia have access to 420.8 to 421.2 MHz as a secondary service, even though the ITU designates this as Fixed, then Mobile, except Aeronautical Mobile, and then Radio Location. Although amateurs are a secondary service, they come after the Department of Defence who are the primary users for those frequencies in Australia. Between 420 and 430 MHz, and from 440 to 450 MHz in several countries, Australia included,...

Foundations of Amateur Radio In the community of radio amateurs scattered around the planet we have a habit of getting together with others to have fun in whatever shape that takes. The obvious ones are HAMfests, car boot sales, raffles and other amateur adjacent pursuits, but we also do things like licence training, weekly on-air nets, contesting, portable activations, climbing mountains, or hills, setting-up in parks, or lighthouses, we set-up on a field day, just for fun, and find excuses, sorry, reasons, for any number of other activities. Some of these are solitary affairs, but many are best enjoyed shared with multiple friends, both old and new ones. Having been a member of this community since 2010 I've come to observe an aspect of this community that is odd, to say the least. We organise all these events, but rarely promote it beyond a single email to three people, if that. It's almost as-if the average organiser thinks that their event permeates the community by magic osmosis. Even if there is any form of promotion, there's sometimes a date and time, but hardly ever does it show that time in UTC, even if it's a radio event, it's like we've forgotten that radio waves pass through time zones, or there is a misconception that everyone on the planet knows what your local timezone is, let alone if it's summer or winter time at the time of the event. So, what does promoting your event look like if you actually want people to know about it? For starters, you should consider who you want to have as a participant. A local HAMfest is unlikely to attract people from around the globe, but Friedrichshafen and Dayton are examples that contradict that notion. A VHF-only event might be intended for local amateurs, but what if it allows for satellite or digital contacts, like say via Allstar, IRLP or Echolink? Similarly, you might run a weekly on-air net, but have visitors from around the planet. The point being, that your audience might not be exactly what you initially think. In other words, there might be people playing from further afield. Consider that when you announce what time the event starts, and finishes. Speaking of finishing, adding an expected closing time is helpful for participants where only one member of the family lives and breathes amateur radio and the rest just want to get on with their respective lives, so consideration is welcome. Aside from telling your audience when and for how long the event goes, adding a location is not optional. You'd be surprised how many events say things like: "it's again in the usual location", or "we're at the community hall" without ever publishing an address. I can tell you, it's fun discovering that the name of the hall isn't unique. Now, for the big one. After putting the information together about the event itself, where and how do you announce it? For starters, on your own website, in whatever form that takes. It serves two purposes, announcing to the world what is happening, but it's also the definitive place where the right information is published. This is important because things change, get cancelled, moved, updated, whatever. Life isn't static, so you need to define a place where the official announcement lives. At this point I'd like to mention that this is often where promotion stops. It's easy to think that in your universe everyone you know is aware of your website, but that's just not true. A single place to publish is not the end of the process, it's the start. Then you need to use things like the local news broadcast, the national news broadcast, the international news broadcasts, contesting websites and calendars, social media, fediverse and whatever else you can get your hands on. You need to include it in your own club news, in club newsletters from other clubs, on the local amateur notice board, you need to talk about the event on-air, share it during on-air nets and if it's recurring, tell the world that it's going to happen again next...

Foundations of Amateur Radio Recently I was given some radio data captured on the 40m band. Using a piece of software called "Universal Radio Hacker", I attempted to decode it. At the time I thought that this might be Morse code, since then I've been told by someone who has been using Morse longer than I've been alive, that it isn't. I shared the data on my VK6FLAB GitHub repository where you can download it and see what you learn, and perhaps repeat what I did, or better still, improve on it. Over the years I've talked a little about how Software Defined Radio or SDR works, essentially it's a glorified Analogue to Digital converter, much like the sound card in your computer, which does the same, albeit at a much lower frequency. As it happens, you can represent the signal that comes into your radio antenna as a series of values. Essentially, the stronger the signal, the bigger the number, the weaker the signal, the lower the number. Let's talk about the characteristics of this signal. It consists of two parallel signals, in opposition to each other. The first signal jumps intermittently between 7 kHz and 40 kHz, where the second jumps between -7 kHz and -40 kHz. The recording is marked 7.06 MHz, so if we think of that as the central frequency, the whole signal sits between 7.02 and 7.1 MHz. This 80 kHz wide signal is not something you'd typically be able to hear using a standard amateur radio receiver which tops out at about 3 kHz bandwidth. It's so wide that you couldn't even hear more than one of the four tones at the same time. Randall VK6WR, who supplied the recording, spotted it on a waterfall display showing a chunk of radio spectrum, in fact, a $25 RTL-SDR dongle could receive this signal. Aside from the fact that this is a really wide signal, well at least in traditional amateur radio terms, it was interesting in that it was heard on the 40m band. As it happens, just after I shared my initial exploration, I was told by several other amateurs that they had heard the signal. I even saw it on a WebSDR in India and attempted to record it, but failed. As it happens, a few weeks ago, I was playing with something called "CAN Bus", or Controller Area Network, a technology that was designed in 1983 and is used all over cars for things like sensors for speed, engine temperature, oxygen level, detonation timing and anything else that's happening inside a car. You might know the end-user view of this called OBD2 or On Board Diagnostics, second generation. I was looking into it because my car has been acting up and I've been trying to track down the root cause. Anyway, I learned that CAN Bus is implemented using something neat, "differential signalling", where two wires each carry the same, but opposite signal, so they can be combined to ensure that in an electrically noisy environment like a car, the information still gets where it needs to go. Seeing the radio signal Randall shared, reminded me of this. Noise immunity is a useful attribute in digital HF communication, so I can understand why it was done like this, but it also means that either signal was sufficient to start to decode the information. We can use Universal Radio Hacker to show us only half the signal using a band pass filter. I then decided that the 40 kHz frequency was "on" and represented by a "one" and the 7 kHz frequency was "off", represented by a "zero". Of course that's entirely arbitrary, there's no reason that it cannot be the other way around, but for our purposes it doesn't matter at this time. That said, we don't yet have enough to decode the actual signal. We need to figure out how long each switch, or bit, lasts, because two zero's side-by-side or two ones side-by-side would look like a long "off" or a long "on". Using that logic, you could also say that the shortest possible duration for a 40 kHz or a 7 kHz tone would represent a single "one" or a single "zero". Of course, this is a simplified view of the world. For example, the data...

Foundations of Amateur Radio Recently I was helping a friend erect their newly refurbished multi-band antenna and during the process we discussed the notion of tuning an antenna that's high in the air. They made a curious response, in that they'd tuned the antenna on the ground before we started. I asked how this would work, since as I understand the process, this changes things once it gets in the air. They assured me that while the actual SWR might change, the frequencies at which it was resonant would not. This was news to me because I've been putting off erecting my own multi-band 6BTV antenna mainly because I didn't really want to face having to erect it, tune it, lower it, modify the elements, erect it, tune it, etc., all whilst standing on the steel roof of my patio. Would this phenomenon be true for my antenna? It occurred to me that I could test this idea, not only for my antenna, but for other antennas as well. In my minds-eye, I saw a video displaying the pertinent attributes of an antenna, SWR, gain, radiation pattern, and whatever else I could think of, animated with the modifications of things like height and ground radials. If this sounds familiar in some way, it's because I've been here before. This time the outcome was slightly different, since I found a tool that can optimise antennas using a genetic algorithm. What I mean by that is an automated process where you can test variations of a thing, in this case antennas. Rather than design each antenna and test it, you essentially generate antenna designs and tweak them to determine the best one. Then you use that to generate the next series of designs. Rinse and repeat until you have what you're looking for. There's a whole field of computer science dedicated to this and unsurprisingly the rabbit hole goes deep. The tool is called "xnec2c-gao" and it's written by Maurizio DC1MDP. The name of the tool hints at its nature, working in combination with "xnec2c", written by Neoklis 5B4AZ and maintained by Eric KJ7LNW, you'll find links to both tools on the xnec2c.org website. How the two tools work together is a beautiful dance. The antenna modelling tool, xnec2c, can read an antenna definition file and detect if it changes, at which point it can redo the simulation, which it can output to another file. The genetic algorithm optimisation tool, xnec2c-gao, can detect the changed output and update the antenna definition file, and the process repeats. Which brings me to a pro-tip, for this to work, you need to configure xnec2c to do two things, detect the changed definition file, and write the output to CSV, both of these options can be found in the "Optimization Settings" menu, just so you don't spend an hour banging your head against the desk. Between the two tools, the antenna definition evolves and you end up with a design optimised for your purpose. The default does this for SWR and gain. Mind you, I tested a multi-band dipole which managed to find some interesting designs, but didn't pick them because a low SWR combined with a high gain, for reason't I don't yet understand, wasn't considered better than a high SWR with a high gain, so there's some work to be done. As a software developer I have a sneaking suspicion that it's adding the two, rather than picking the highest gain combined with the lowest SWR, but I haven't confirmed that. As I said, deep rabbit hole. While we're not yet at the video display stage, for the first time I can get a sense that this might come to pass. There's plenty of work to be done. For example, the antenna display on xnec2c during the process seems broken, there's no way to output gnuplot files during the process, and capturing the various charts in real-time will require work, but all that seems if not easy, at least possible. Meanwhile, I'm attempting to locate an antenna definition file, preferably in .NEC format for my 6BTV antenna, so I can use this combination of tools to discover if tuning it on the ground will work...