Foundations Of Amateur Radio

Foundations of Amateur Radio Antennas and propagation are the two single most discussed topics in our hobby, that and how an FT8 contact isn't real. Not a day goes by without some conversation about what antenna is the best one and by how much? In my opinion it's a futile effort made all the worse by so called experts explaining in undeniable gobbledegook, or sometimes even using science, just how any particular antenna is a compromise. The truth is that most conductive materials radiate to more or lesser degree. Sometimes there is enough of that to make it outside your backyard into the antenna of a fellow hobbyist. To make a point, as is my wont, over the past months I've been conducting an experiment. It's the first in a series all related to antennas and propagation. As has been said, the difference between fiddling and science, is writing it down, so this is me writing it down. I'm using the tools available to me to explore the various attributes of my station and how it affects what's possible. I wil

Foundations of Amateur Radio One of the first questions a new amateur asks is "Which radio should I buy?" It's a topic I've discussed at length and the answer "It depends." is unhelpful without doing more research, but after you've done the work, you'll be able to answer it for yourself. A question that is just as important, but not asked nearly enough, frankly, I've not heard it in the decade I've been part of this community, is: "How should I build my shack?" The answer is just as useful, "It depends." So, let's explore what precisely your shack design depends on. Let me start with pointing out that I'm not here to give you answers, you can watch hundreds of YouTube videos, read a gazillion web-pages and get no closer than discover how others have answered this question. It wasn't until recently that I understood that it was a question at all, but airing my frustration at the level of dysfunction of my shack unearthed it and in attempting to answer my own question, I started to explore the landscape. As

Foundations of Amateur Radio Over the weekend I learnt to my chagrin that my shack was not ready for the contest I decided to participate in for an hour. Truth be told, it was probably me who wasn't ready, but I'm going to blame my shack, since it can't argue and besides this is my story. It started off with turning on the HF radio. That involved turning off my 10m WSPR beacon which is transmitting its little heart out 24 hours a day into the one vertical antenna it shares with my HF radio. Turning off the beacon was simple enough, reach into the mass of cable and dig out the USB power lead that plugs into the beacon. Then follow the antenna coax to the correct switch. Whoops, that's the GPS coax, the other one, there's the switch, now switching it to the HF radio. Why didn't the sound change, actually, come to think of it, what sound? Hmm, the audio is going into, nothing, actually, it's going into the audio mixer that's turned off. Turn that on. Then audio at last, nope. Hmm, oh wait, the audio needs to

Foundations of Amateur Radio Identifying the problem is the first step in fixing it and with that I want to talk about emergencies. One of the very first things I was told about our amateur radio community was that we're here for when emergencies happen. Our purpose is to communicate, so in a crisis, we can assist by supplying communication to the situation. I've talked about some of this before. Preparedness in the way of on-air training by contesting, in getting gear ready and even exercises for when this occurs. There are amateur clubs dedicated to putting up repeaters for just such an eventuality. Recently there was a local news item about radio amateurs banding together, sending gear to fellow amateurs who were hit by severe flooding that wiped out their shack and with it their ability to communicate. Another event was a friend who lost a big chunk of his shack when his basement flooded. Across Australia and in other parts of the world in recent times we've been witness to the most devastating fires

Foundations of Amateur Radio The art of amateur radio is many things to many people. For me it's a technological challenge, a learning, a way to broaden my experience, a way to be technically active away from my consultancy. The place that amateur radio takes in your life might be the same, or it might be completely different, as varied as the people I've encountered since I became an amateur. People from all walks of life with different experiences and vastly different stories. Truth be told, in the decade that I've been an amateur, I've spoken to and met people from more diverse backgrounds than in the forty years before that. I make that statement as a person who migrated across the globe twice, travelled through a dozen or so countries, stood on stage in front of thousands of people, taught countless classes and as a radio broadcaster interviewed people from all over the planet. From paraplegic to quadriplegics, from people with terminal diseases to people struggling with their identity, from astronome

Foundations of Amateur Radio One of my favourite activities is contesting. Essentially it's a time-limited activation of your station for the purposes of testing your skill and station against other participants. Contests are controlled by rules as varied as the amateur community itself. That said, there are common terms and concepts and if you're not familiar with them, they can lead to confusion and disappointment when you inadvertently break a rule and see your hard work vanish into thin air. I will note that what I'm discussing here is not universally true, so read the rules for each contest you participate in, something you should already be doing since rules are refined over time and it's rare to keep the same rules between years. A contest starts and stops at a specific time, often expressed in UTC, or Universal Coordinated Time. You should know what your local timezone is in relation to UTC and take into account any variations like Summer and Winter time. Any contacts made outside these times don'

Foundations of Amateur Radio After weeks of attempting to get some noise, any noise out of my PlutoSDR I have finally cracked it. Not sure if cracked it refers to my sanity or the outcome, but beeping was heard from the Pluto on my radio, so I'm doing victory laps around the house, all conquering hero type affair, complete with whooping and hand waving. In the end it all came down to serendipity and truth be told, I know it beeps, I've heard it beep, it does so on a predictable frequency, but why it exactly works is still a mystery that has yet to be discovered since the documentation I have isn't sharing and the example code I have contradicts what I'm seeing. For context, a PlutoSDR, or Pluto, is a very capable software defined radio, perfect for experimentation. I've talked about it before in the context of using it as a receiver. My most recent efforts involved coaxing my Pluto out of a corner after it sat there sulking for weeks. Turns out that not only was my USB power lead broken, which caused the

Foundations of Amateur Radio The other day I took delivery of a shiny new circuit board populated with components and connectors. Knowing me, you'd assume that I'd been the recipient of some kind of software defined radio gadget and you'd be right. One of the connectors was a micro USB socket, intended to be used to plug the hardware into a computer and to drive the circuit board. The board came to me by way of a friend who saw it online, waxed lyrical about it and for less than $35, who could begrudge this exploration into a new toy? Once it arrived, it sat on my shelf for a few weeks, enticingly packed in an anti-static bag, transparent enough to see the device inside, taunting me to open it up, plug it in and have some fun. Today I opened it up and started researching my new gadget. It didn't come with any user manual, no URL, no model number, but it did have a callsign on it, so I started there. I'll note that I'm not going to repeat that callsign here for a number of reasons, which I'll get to. My

Foundations of Amateur Radio One of the topics I've been talking about lately is the idea that we might be able to measure the performance of your radio in some meaningful way using equipment that can be either obtained by any amateur, or by introducing a process that allows results to be compared, even if they have been generated differently. Recently I came up with a tool that automatically generates a spectrogram of an audio recording. That on its own isn't particularly interesting, but it's step one in the processing of an audio signal. In addition to the spectrogram, I also created a tool that generates a tone frequency sweep, think of it as a tone that changes frequency over time, let's call it a sweep. If you combine the two, you can generate a spectrogram of the sweep to give you a starting point or baseline for comparison. You can build on that by using your radio to transmit that sweep and record the result using a receiver. In my initial experiments, I used an RTLSDR dongle to receive the audio

Foundations of Amateur Radio Recently I've spoken about measuring the frequency response of your radio and what the benefits of doing so might be. Today I've got some progress to report and some initial discoveries. Again, this is preliminary, but then all of this hobby is experimentation, so that should come as no surprise. Let's start with the mechanics of what I'm doing and a "duh" moment I need to confess. The aim of this process is to transmit a known audio signal, receive it, record it and create a spectrogram from it. This allows us to compare the original spectrogram against the received one and show just how the audio path has been affected by getting the audio into the transmitter, the processing by the transmitter, the propagation between the transmitter and receiver, the artefacts introduced in the receiver and any recording device. To begin this process I started off with an audio file of my voice. That wasn't very helpful, since it's a complex signal and comparing my voice before and after i

Foundations of Amateur Radio During the week I was reading a comment from another amateur about digital modes. Tucked inside that comment was a phrase that could easily have been overlooked, but it reminded me that there is plenty to learn and test in the field of amateur radio. The phrase, "requires actual understanding of audio level paths" was uttered by Chris, VK2CJB and it prompted a brief conversation at the time, but I've been working on it ever since. Where I arrived at is an attempt, incomplete as yet, to design a mechanism to show the impact of various transmitter settings on the received audio in such a way that you can test your own gear and see the result. Before I explain how I'm doing this, let me describe why it's important. Using a radio in concept is pretty simple, if you yell into the microphone, the audio comes out distorted and if you whisper, it might also be distorted, but in a different way, neither is conducive to communication. One way to improve this is a tool called the ALC.

Foundations of Amateur Radio On the 6th of June, 2004, two Brazilian amateurs Roland, PY4ZBZ and Arnaldo, PY4BL made a historic contact on 40m. The distance was not particularly significant, only 70 km, but the mode was. Using 2.1 kHz bandwidth, so it could fit within an amateur radio SSB transmission, they used software created by Swiss amateur Francesco, HB9TLK to make the very first HamDream exchange. This technological advancement represents the birth of what we now call HamDRM and Digital SSTV and how it came about is an adventure that needs documenting, since what we have is written in a combination of Portuguese, German and English, cobbled together from broken websites, archives, source code, commit comments and lost links. To provide some context, there is a broadcast radio mode called DRM, or Digital Radio Mondiale. At this point I should mention that this has absolutely nothing to do with Digital Rights Management with the catchy acronym of, you guessed it, DRM. As you might expect, this acrony

Foundations of Amateur Radio A couple of days ago, after months of anticipation, an unassuming little box arrived on my doorstep. Inside the box was a nondescript electronic device with two SMA connectors and a USB socket. Other than the branding, there were no markings on the device and it came without any instructions. It did come with a couple of SMA adaptors, which came in handy. A little research later determined which of the two SMA adaptors connected to an antenna and which connected to a radio. The gadget itself is called an upconverter. It's an interesting little device that essentially mixes two frequencies together, creating two new ones, start with say 720 kHz and mix it with 120 MHz and you end up with 120.720 MHz and 119.28 MHz. In other words, if you mix two frequencies together, you end up with both the sum and the difference of those frequencies. If you have a radio that can listen to 120 MHz, but cannot listen to 720 kHz, then using an upconverter, you can, as it were, expand the frequ

Foundations of Amateur Radio A little while ago I mentioned in passing that I was considering implementing a parrot repeater to help determine how your radio is performing. Discussion afterwards revealed that not everyone had the same picture in mind, so I thought I'd share with you some of what I'm considering and why. Most of the modern radio landscape revolves around hooking a computer up to some type of radio frequency capable device. Commonly it's the audio and control signals that travel between computer and radio, but there are plenty of examples where raw data makes the journey, like in the case of an RTL-SDR dongle. That journey is increasingly made using USB, the cable, not the sideband, and limits are based around the maximum speed that a Universal Serial Bus has. Essentially the amount of data that you can process is limited by how fast your computer can talk to the radio. For my parrot repeater, I'm imagining a device that can receive RF from any radio and process that signal to determine wha

Foundations of Amateur Radio The other day I received an email from a fellow amateur, Elwood WB0OEW. We've been exchanging email for a little while and having been in the hobby since before I learnt to ride a bicycle, he's always got some interesting insight into something I've said and an encouraging word to share. This time he introduced me to a project he built and published a couple of years ago. It's a variable frequency standard, built from parts and, at the time, costing all of about $150, more on that shortly. Compared to the microwave oven sized HP-606A signal generator sitting on my bench in bits, with some diligent layout, this project could fit inside one of the valves that drives that massive hunk of equipment. As an aside, truth be told, I'm a little afraid of the HP. It managed to pop the RCD, a residual current device, or safety switch, in my house and in doing so, took out the UPS that powers my main workstation, so, not unexpectedly, I'm reluctant to repeat the experience. Once I understa

Foundations of Amateur Radio The other day I came across a how to video on becoming a radio amateur. It's a recurring kind of publication, the kind that I've contributed to in the past. I wondered what it would take to leave the hobby. First of all, I'd have to let my callsign lapse. That's easy enough, but I paid for five years, so it's going to take a while. When it has finally ceased being mine, have I stopped being an amateur? For one, my qualifications would still be in the regulator's database, likely well beyond my breathing years. I wonder if they implement the right to be forgotten? Another thing I'd have to do is stop knowing about how antennas work in day-to-day situations. I'd have to stop noticing the location of free to air television antennas, mobile phone towers, Wi-Fi antennas throughout the community and even the network in my home. I'd also have to say goodbye to all the friends I've made around the place. There's hundreds of people scattered around the globe who with a single word mi

Foundations of Amateur Radio After discussing the notion that it's not really possible to determine how your gear is performing without measuring, several people commented that in the good old days an amateur was expected to have sufficient equipment to test performance of their gear. I flippantly pointed out that once upon a time, computers ran on punch cards too. That's not to dismiss the notion of testing, but rather that times have changed. Testing equipment that was suitable in the 1980's is still available around the place, but expect to pay for it. Some of it is still relevant, some less so. Even if you do acquire suitable equipment, how do you know if what you're measuring is real? How do you know if the frequency counter that you have is accurate, how do you know if 1 Volt is 1 Volt, or 1 second is 1 second? As I've said before, measurement is the act of comparing two things. If you think that's ludicrous, consider the rulers and tape measures in your home. They all indicate the same measurement,

Foundations of Amateur Radio When you spend some time in this hobby you're likely to find equipment with similar performance for vastly different pricing. At one end of the spectrum you might compare a cheap $25 hand-held radio to a $450 one. At the other end, a $1,500 SDR or Software Defined Radio against a $4,500 one. Those examples are for brand name devices, which generally speaking have published specifications, come with regulatory approvals, a wide user base, reviews and a distribution network. If equipment is found to be operating out of specification, a regulator might seek a remedy or ban the sale of the equipment. Those various sources and processes make it possible to compare those devices in a structured way to discover just how deep into your pockets you need to reach in order to acquire a shiny new gadget. If you buy any of these devices in the used market, you have no way to determine just how far from the factory specifications the device you're contemplating has deviated. Is that waterpr

Foundations of Amateur Radio For some time now I've been discussing the potential of weak signal propagation and its ability to create a live map from the data that your own station transmits. There are several systems in place that show a map of where and when your station was heard in the past little while. Using 200 milliwatts, I've been transmitting a WSPR or Weak Signal Propagation Reporter beacon on 10m for the past few weeks. At the moment, the furthest away my beacon has been heard is 13.612 km away. That's an 0.2 Watt signal heard on the other side of the planet, on 10m. As distance goes, it's a third of the way around the globe. I must point out that there's no way of knowing if this signal travelled the short path or the long path. If you've heard those terms, short and long path but were wondering what they mean, here's how it works. If I get on my bike at my QTH in Perth in VK6 and peddle East until I hit Sydney, I'll have crossed Australia, taken about 184 hours and travelled about 3.746 km.

Foundations of Amateur Radio One of the regular topics of conversation in amateur radio, especially for those new to the community, is where to start? The sheer volume of available options is often overwhelming. If you've never encountered the complexity associated with this amazing hobby the experience can be disheartening and even demoralising. In my early years I was results driven. Getting on air, making noise, logging a contact, adding a country, winning a contest, rinse and repeat, get better, do more. There have been numerous occasions when I came home from one of my adventures disappointed, sometimes bitterly so. That happened for quite some time, until one day I realised that the journey in and of itself is the reward. That might sound disingenuous, so let me illustrate. This week I set-up an automatic beacon in my shack that can be heard by stations around the planet, letting me know just how far my signal can travel at any particular moment, using my own station antenna and local propagation.