 I'm Jenny List. I'm a bunch of friends from Oxford Hack Space. And here are some things we're doing in Oxford Hack Space. I'm here to talk about WISPA, which is a radio protocol. The Grandly titled piece was asked for a blurb. You vs. the atmosphere, an almighty struggle. I hope it doesn't turn out to be a disappointment. Now, next slide. I'm going to introduce amateur radio because I'm guessing there will probably be one or two radio amateurs amongst you, but there'll probably be one or two who aren't. So you'll probably have sort of have preconceived ideas what amateur radio is, you may well have seen things like the Tony Hancock Hancock's half hour radio amateur sketch where he took the piss out of us. I'm afraid some of those things are true. What is amateur radio? It's licensed experimentation with radio. This goes back to between the wars. Radio was just becoming established as technology its own right. It was the exciting cutting edge thing of its day radar and all sorts of things like that hadn't yet been invented. And naturally there were people like us who wanted to experiment with it. And fortunately government saw that this had potential to develop a sort of cadre of people who were experts and could produce what became an electronics industry. And so they licensed people like us to experiment with this exciting new technology. We're given specific frequency bands that we can play with and we can more or less give or take a few things do what we want within those frequency bands as long as we don't interfere with anybody else outside those frequency bands. And we will have to pass an exam to get a license and when we have a license we're given a call sign in the UK it's off-com but all the countries have their own licensing body. My call sign is Golf 7 Charlie Kilo Foxtrot Golf because it's a British call sign. I think there's G's, there's 2's and there are M's are British call signs. And Golf 7 because it was a Class B call sign back in the day from the late 1980s. And Charlie Kilo Foxtrot which is a simply a sequential number of digits. I believe nowadays they give out vanity call signs but back in the day we had real call signs. It's an international worldwide community. This predates the internet by 60 years or whatever. I believe the only place in the world that doesn't have amateur radio is North Korea. So if you ever find a North Korean radio amateur you'll have millions and millions of radio amateur geeks queuing up just to have a contact with him because he is the rarest person on the planet. We're rooted in maker culture. Back in the day you couldn't go out and buy a radio you had to make your own before the war and so a huge culture of both making your own kit and sharing your own designs appeared. Richard Storman was probably a gleam in his father's eye at this point. There was no open source movement. People just shared designs. You'll find if you are a radio amateur you'll find you're using designs with sort of very old sounding call signs. Like for instance you'll find people using an antenna called a G5RV that was developed by a bloke in Gloucestershire in the 1940s and 50s. He just shared his design with the world because it was a good design and everybody wanted a good antenna. There are loads of examples of things where radio amateurs have between them, developed things, refined them, swapped them around, come up with new designs. In a way it's a sort of a prototype for the sort of maker culture that we all know now. It's a multi-faceted pursuit and we come back to the Tony Hancock thing. Unfortunately there is a certain type of radio amateur who gets their licence, goes out and spends a thousand quid on a very fancy Japanese box of tricks and fancy antenna and thinks they're the dog's watsits because they work the world and they will often think oh I've got a very old call sign with my Japanese rig and my fancy antenna so I can look down on you who've got a new call sign but you build your own kit and I don't. Unfortunately it's all true. I mean if you go down on 80 metres on a weekend morning you'll find endless old gits talking about the war and their allotments but fortunately it's a multi-faceted pursuit. There are as many different things to pursue in amateur radio as there are radio amateurs. Okay some people go out and buy fancy rigs and collect countries around the world to work. Great that's their thing. My thing is building toys, building little boards and tiny little transmitters. I don't really care if I never work anybody off the transmitters I've made have sort of proved they work and yeah I've made myself a little rig and never worked anybody on it. That's my thing. Somebody else's thing will be something completely different. You probably won't hear this said very often but now is a very exciting time to be a radio amateur. Because traditionally it's an analogue thing. I mean there will probably be many radio amateurs who will go, aha, no. Because obviously the basic form of radio amateur is Morse code which is very digital. Even use a finger. But traditionally all the circuitry has been analogue. You'll have an analogue receiver, you'll hear stuff in the speaker, whatever. It's a very exciting transition at the moment because you're moving to digital. You're moving to software defined radio, software defined transmitters, software defined receivers. You're moving to wonderful chipsets designed for other things that have loads and loads of cool applications in amateur radio. I was for instance looking at a chipset designed for those 430 megahertz remote control things a week or two ago. For 79 pence you basically get a software defined 70 centimetre amateur radio transmitter. How cool is that? And so all this kind of stuff make it an exciting time to be a radio hacker. At least I think so. So hang on, next slide. Radio propagation. Now there's a problem with radio. It's an electromagnetic wave like light. And if you're in free space out in the deep black of beyond it would just go in a straight line. So if you can see the transmitter you can receive it. Now unfortunately the earth gets in the way and everything beyond the horizon if you can receive it you're not getting a straight line path. You're getting some interaction with the atmosphere. It's being bounced off the atmosphere, it's being bent round the earth. There are multiple different ways that radio get from A to B. It's not just a foregone conclusion that when you hit the button on the transmitter it will reach the other person. It depends on all the factors of the atmosphere, it depends on the power of your transmitter, it depends on the weather, it depends on the terrain. And this is the problem that faces radiometers. And this is one of the facets of amateur radio that many people get seriously into. Just mapping propagation. Next slide. Which brings me on to this guy. Joe Taylor, K1JT. The Americans have vanity two letter call signs. He's obviously got a hidden one. Now Joe Taylor is a scientist. He's a Nobel Prize winner and astrophysicist. I think he's, was it something to do with pulsars? I think his Nobel Prize, you'd have to look it up. I'm afraid I don't know on that one. He is a, his special interest is radio propagation. And he's developed a whole series of digital radio modes, transmission modes, basically ways of encoding stuff onto radio waves, which are designed specifically to test the limits of radio propagation. So to get contact from A to B with usually minimal stuff like just your call sign and where you are with the minimum power possible. Because he's, he's wanting to push the boundaries of science. And this is important because there is a scientific aspect to what I'm about to talk to, which is, we'll talk about, which is whisper. He developed whisper as latest at the time in one of a series of protocols in 2008. Now whisper, the nub of this talk, weak signal propagation reporter. It's a beacon mode, which means that you don't sit and operate your whisper rig into the night. You turn on a box, turn on your computer and go away and make a cup of tea, or go up to Hebden Bridge and do a talk. If you were to type golf 7 Charlie Kilo Foxtrot into the website I'm about to show you, you would find my whisper beacon sitting there talking to the world, and even, I hope, some people hearing it. It's a binary format, so you take your call sign, in my case golf 7 Charlie Kilo Foxtrot. Your power, which, because you want some parameter of how far is this getting on what power. So your power in dB milliwatts, which is a ratio of your power in milliwatts. Your grid locator, which is as best described as the national grid parameter radio. There is a worldwide grid, which is a way, a formula for turning less student longitude into a string of numbers and letters. For instance, my home location in Oxfordshire is India Oscar 91 Lima Whiskey. I should have really have looked up the location for this one and had it pat, but there you go. So you have those text string call sign power grid locator. It's encoded and compressed into 50 binary digits. That is encoded onto the radio wave using frequency shift keying. So one frequency is one, one frequency is zero. Now what makes whisper special? Six hertz total bandwidth. Now six hertz is tiny. If you listen to a whisper transmission on a radio, you'll hear a tone. You will not hear that change. You know it is changing 50 times in a packet, but you won't hear it because your ear just can't register six hertz. Now a typical speech transmission will be about two and a half kilohertz. So that's 2,500 hertz in width. So when you're listening, you're actually hearing a 2,500 hertz slice of radio. Now to get heard in that 2,500 hertz, you have to puke out a lot of power from your antenna for the guy at the other end to hear it. Now the whole point of having a six hertz bandwidth is because it's such a tiny slice of radio you're listening to, the transmission power required to get heard at the other end is also relatively tiny, which basically what makes whisper so interesting from my point of view for mapping propagation. It's very, very strict timing in whisper. Your transmitter would have to be synchronized to world time. People will do it with a GPS receiver. I do it with NTP over the internet. So typically a whisper or transceiver will be connected to the internet because it's the quickest way to do it. And even UTC minute, every whisper transmitter in the world will start transmitting. It takes about a minute and 50 seconds to transmit the whole packet of data. Now this at the bottom can survive a minus 28 dBm signal to noise ratio. That basically means it can hide in the noise. You wouldn't hear it and the computer can still detect it. It can survive conditions where you simply wouldn't be able to even know that there was a station there if it was a voice station. I borrowed this table from Carol Milatso, KP4MD. She's done quite a lot of presentations on whisper in the state, so didn't actually have a license on her website, so I may have nicked this, but I hope she won't mind. This compares the amount of power you'd need to do the same job with various different radio modes. At the bottom you've got a single sideband, that's your speech radio that most radiometers use. And underneath you've got teletype, which is the oldest digital mode. Imagine that as like a 50 board mode M connected to a radio. Below that you've got Morse, CW, Continuous Wave, and then you've got several different varying digital modes. That's a JT, Joe Taylor mode, same guy who developed whisper. And at the bottom you've got whisper. Now on this side you've got the equivalent power that you would need. So to get the same distance in single sideband on a given frequency you'd need 25 kilowatts to what you'd need 5 watts of whisper. So as you can see whisper is a very, very efficient way of getting radio waves around. Now I find it's kind of funny. Carol Milatso's American, she thinks 5 watts is a small power. It's about 500 times the amount I use for my whisper transmitter. Whisper's great, you can talk great distances with tiny power. But what makes it really powerful is a big data aspect. Every whisper receiver is connected to the internet. And every time it hears something it sends that into a centralized database. This happens to be a map that I grabbed from the screen earlier in the week. There's me, golf 7 Charlie Kilo Foxtrot in Oxfordshire. And I've got pretty tiny power on 20 meters which is 14 megahertz. So I'm not getting across the world. But I'm instantly just on an ordinary day getting all the way across Europe. Now I think this is why Joe Taylor did it. Because he's a scientist, he wants data. He doesn't want to say I've worked in these countries. He wants to gather data, he wants to model the atmosphere. And this is, to me, is where whisper becomes really powerful. Because every spot gets uploaded. It's been running for six, seven years, something like that. And there are now, what's it, 320 million spots in the database when I looked earlier in the week. And it's going up by about 350,000 spots a day. So that's a huge trove of data. And of course it's all downloadable. So open source, you can do what you want with it. If you are interested in the atmosphere, in the properties of the atmosphere, you've got an enormous trove of year upon year of atmospheric data ready to play with. And that makes it very, very powerful indeed. You can say, OK, I know that there's a high pressure coming up from the Atlantic. And you might say, hey, now I know from experience that that means I'll get a particular lift in a particular direction. But now you can model that. You can go to the data and say, right, find a time in the past when a similar high pressure or whatever, a similar time of year or a similar auroral event or a similar ionisation of the atmosphere and model on real data. This provides you with an unbelievable trove of data that you would never have had in the past. That's the extra angle that the internet brings to otherwise a fairly dry radio protocol. So how do you do whisper? Whispers, at its most basic form, distributed as a piece of software. It's a GUI package, Mac, Windows, Linux, GPL'd. It works through your sound card. It's connected to a single-side band transceiver, a typical radiometer might have in their shack. It's a software-defined radio, but probably not as you would understand it. What a single-side band receiver does is it takes that little 2.5 kilohertz slice of radio and shifts it down to audio. Effectively, if you listen on a sound card, you can do all your software radio maths on that audio, and you've basically got a software-defined radio that works on that little 2.5 kilohertz of radio. What you're seeing here is a waterfall. Each one of these slices is one whisper packet, so one minute and 50 seconds. That is 200 hertz wide, the 200-hertz segment of whichever band that this happens to be tuned to at the moment. Each one of those lines is a whisper packet that this receiver has picked up. The really cool thing about it being software-defined radio is it doesn't have to listen to just one. It can have 20 different packets appearing, and sometimes you will see stripes like this with lots of packets, and it will log them all. And because they're only 6 hertz wide, they're all on different frequencies, and the maths is quite up to spotting them, it's got one minute and 50 seconds in which to do it while it's receiving the next one after all, and a lot of people will just leave this running in their shack. Personally, I don't like doing this because it means I have to leave a radio, a computer, and various other things running, and I think it's power hog, but that's what people do. And it's a perfect example of what I was talking about on radio being an exciting position of software-defined radio starting to appear. 25 years ago, when I got my licence, software-defined radio didn't even exist. I mean, if you were probably the military or something, you probably had some incredibly expensive kit which probably isn't even near what you can buy for 100 quid nowadays. Technological advancement has given us the ability to do what is quite hefty computing on an ordinary commodity desktop, which opens up whole new vistas for an old pursuit. This is more my kind of thing for whisper. If you have a tiny protocol, it makes sense to have a tiny transmitter. You don't need a thing capable of kicking out 100 watts and talking to Australia with SSB when all you want to do is kick out a few milliwatts. These are a couple of commercial ones. They're both based on embedded microcontrollers. That one, I think, is a pick, but it might be an atmail, but it's using a direct digital synthesiser module to basically generate RF directly. The one below is a pick and a voltage-controlled oscillator. They're both different ways of achieving the same thing. I think those cost in the region of 20 or 30 quid. I think that one, if you buy the display board, costs closer to 50 quid. But these are just buy the kit, solder it up, plug it in, connect an antenna, and off you go. The power is so tiny. You don't even need to worry about the antenna being tuned. It'll just work. It's great. This is what I use. I use a Raspberry Pi. A Raspberry Pi comes with a really neat piece of hardware. It's got a clock generator, which is designed to provide clocks for external peripherals. But, effectively, it's a synthesised RF source that will work from low kilohertz up to about 250 megahertz. It's just a 3.3-volt IO line, but a 3.3-volt IO line can sink about 10 milliwatts. 10 milliwatts, as you saw earlier, from my little map there, can get you into an awful lot of places. I made a little board. I actually put this on Kickstarter. It's basically a prototyping board for experimenting with radio with a Raspberry Pi. Unfortunately, it didn't make it on Kickstarter, but this isn't actually such a bad thing. I'll tell you why it didn't make it. I thought I could make 200 of these, and about 180 people decided they wanted one. But there's a lot to be said for having a Kickstarter that fails, because, of course, if your Kickstarter succeeds, you actually have to ship the thing. Whereas if it fails, you just say, oh, well, I really put work in, but you don't have to do a damn thing. I am pursuing putting that on sale and producing a version 2 with slightly different IOs and a little bit more prototyping space, but that'll be sold on an individual basis. So I won't have to kickstart to do me hard work for me. On there, there's a circuit. That is a low pass filter. It's an LC network. Effectively, it gets rid of frequencies above a certain amount. The reason for that is the Raspberry Pi kicks out square waves, and one of the properties of square waves is you get the frequency you want. You get twice the frequency you want. You get three times the frequency you want, and that's great. You just better hope that your local airport's emergency channel or your police or whatever on one of those harmonics. So that's one of the reasons why they make us do an exam to get an amateur radio licence is to teach us that you've got to do things like that. Oop, running out of time. I didn't write the software. Off the shelf, just download it from GitHub. Whisper software, just a command line. You just run it, job done. If anybody fancies rewriting it to work with the Raspberry Pi 2, you're a better coder than I am. It phones home to use NTP to get the frequency bang on. I've covered all the other things on there. I put together a more information thing. If you're interested in amateur radio, Radio Society of Great Britain is your first stop there. They like to style themselves as they run amateur radio, but they're basically the old farts I think they'll run amateur radio. Maidenhead grid locators, that's the grid system used in Whisper. It's called Maidenhead because it was a conference in Maidenhead where they decided which system they were going to use. Whisper, that's K1JT's Joe Taylor's homepage. Whispernet, that's where you can mine the data. You can type my call sign in and see how little I've worked. Some quite interesting stuff. There's a supported whisper for Arduino and PIC. There are quite a lot of things out there on the internet to build your own if you're interested. There's Whisper and Pi, the thing I use. I'm Jenny List, Jenny Alto on Twitter. That's my website, languagespy.com. Eventually you'll be able to buy that little board there. It's a bit confusing. Instead of in business, I spent the last five years working with dictionary data for Oxford Dictionaries. My business is actually a language technology business, but you've got to bring some money in somehow. I've started producing amateur radio kits. It's funny how things take you. That's why it's languagespy.com. I hope that's been illuminating.