 All right, let's give it up for Skyler here. So as you already heard, I'm Skyler St. Ledger, and today I'm going to talk to you about software-defined radio and open source and why you care about it. So first I want you to think about how many radios you have on you right now. So you probably might be thinking none of them, but you actually, just in your phone, have four or more radios. You have cellular radio, Wi-Fi, Bluetooth, and GPS. When you go home and you click your garage or opener, that's another radio. You sit down on the couch, turn on your ceiling fan, that's another radio. Radio transmitters and receivers are all around you. You just don't notice them. But there's one thing that these all have in common that differentiates them from software-defined radio. They're all very specific. The radio in your phone has one radio or one subsection of a radio IC that just does Wi-Fi. Another thing for just Bluetooth or just GPS. The your garage or opener, it just opens your garage. You couldn't use it to make a phone call or do something like that. Software-defined radio just goes and it says, instead of having hardware that can only do one thing, it then says, let's move that into software. It makes it where your hardware can do almost anything and the limiting factor is the software that you write. Now you're probably wondering, what are good uses for software-defined radio? So commercially, there aren't that many big applications because software-defined radios tend to be expensive and they tend to be fairly power intensive since what you could optimize in hardware, you now are all doing in software. But they're useful for military applications where you have to have a very, a wide variety of different radio protocols that you're using. And for researching cellular 5G and beyond specifications because you want to be able to very easily change the way you're transmitting or receiving a signal to research that. So with SDR you still need some amount of hardware like this, but it's very minimal. The hardware is just the RF front end which you're receiving is a low noise amplifier and some filters and a mixer. And then that goes into an analog to digital converter to send it to your computer. To transmit, you have pretty much your verse, a digital to analog converter which goes through some filters and whatever and then out in an amplifier out to your computer or your antenna. So this is a traditional radio receiver for in this case it'd be AM radio. And you have your antenna in here. It goes through an amplifier, a mixer that shifts the frequency down to something that's easier to work with. Then it goes through some more filtering and amplifying and is demodulated. In this case this would be AM radio so it takes the amplitude of it and then puts that out to the speaker. This is pretty much what an AM radio receiver would look like with software defined radio. The difference is that right about here you then end up, this is all done in software, the demodulation and the audio part. You still have some of the hardware to receive it because you need hardware but there's a lot less of the hardware and you can change it much more easily because you're doing everything in software. As far as hardware goes, there's a whole bunch of hardware to choose from. This is by no means a complete list. These are just some hardware that I know of and either thing is cool or is cheap. The cheapest one is the RealTech RTL-SDR dongle. This runs you about 10 to 20, $30 on the high end. It started out as actually a TV tuner dongle and someone found out that you can get it to dump the raw data to it. Now you do get what you pay for in that this has a higher noise floor which is what is the quietest signal you can receive and how much effectively static you have in the background. And also it only has about a two megahertz bandwidth which means you can only look at a fairly narrow portion of the spectrum at any one time. There are the things like the FunCube dongle Pro Plus which is a higher quality one. These two are both received only. Everything else here can receive and transmit. The HackRF1 and the BladeRF are probably the two most popular ones. These software defined radio hardware transceivers are both open source. Software defined radio has about a 20 megahertz bandwidth. The BladeRF goes up to I think 40 megahertz. And then there's the USRP which is made by Edis Research. These are like the commercial really nice ones and these are open source as well. The UMTRX is cool because it uses the same hardware transmit receive stuff as the BladeRF but it has two of them so you can be transmitting on one frequency and a different frequency and then receiving on those. There's also the important part of software defined radio is the software. So if you're stuck on Windows, I feel bad for you. You can use SDR-Sharp and HDSDR. SDR-Sharp is closed source freeware. I believe there are older versions that were open source. It's written in C-Sharp and you can use it because it's nice because it installs all the drivers for you. If you're on Unix, Unix, Mac, Linux, one of those BSD, GNU, slash, Linux, whatever you want to call it operating systems, you'll usually end up using GNU Radio which is a framework for taking samples and data from your radio then passing it two different modules to do processing on that and it takes care of all the timing and making sure that the data gets where it needs to go. GROSmo SDR provides hardware drivers and interfaces to GNU Radio so it makes it really easy to connect this radio to GNU Radio or any other radio. And then on Mac and Linux there's GQRX which is a nice piece of software just for browsing the spectrum. There's also software for Android which lets you either connect a either HackRF or real tech dongle to your phone using a USB on the go adapter and you can view the spectrum that way. And there's also an ADS-B receiver which I'll talk about more. So now we're gonna get into some demos. You're all supposed to be excited now. Yeah, hopefully they don't break. If they do, it's your fault. Change my display. Nice thing about running on Mac is you don't have the display issues that you normally have with Linux. Okay, so this is GNU Radio companion. And this makes it easy to prototype or do SDR software. And what it will let you do is, it effectively lets you make a flow graph type thing. So what you have here is a flow graph that's fairly simple. And what it does is it takes the radio in. It will then take, it'll then show you an FFT of it which takes the radio signal which samples it over time and it will then convert it to frequency. And it then multiplies it by a sine wave to shift the frequency down so it's centered. It then filters it and will put it out over audio. So this we can use to listen to an FM radio station. Now one thing you need to do for this is you need to find the radio station. So to do that there's this nice piece of software called Osmo-com FFT. And if you have a GPU in your computer that's supported, you can use this thing called Phosphor. And what Phosphor will let you do is, so this is loading the software on my radio and it will work. And what Phosphor will let you do is it will use your GPU to accelerate the processing of the FFT. So you get a really nice looking waterfall spectrum view which will open. So this is it. So first I want to turn up the sample rate. 20 mega samples per second should be good and turn up the gain and make this bigger there. So what we're looking at now is the FM broadcast band and I should turn up the gain a bit more. Longer antenna. It helps if your antenna is tuned for the wavelength that you're receiving. So FM is, or at least in this, it's fairly low frequency. So you'll want a longer antenna. Frequency tends to be very relative. For some stuff, a few hundred megahertz can be high frequency. For other stuff, a few hundred megahertz is very low frequency. So what we're looking at here is we're seeing, actually I need to set it to the right antenna port. One other thing is some software find radios of multiple places you can connect an antenna. Make sure you choose the right one or else you'll wonder why things aren't working. And anyways, with this you can look at the FM radio spectrum and this should work. There, so now this should work better. So a few things here are there's your sample rate which is how many samples does it take a second? In this case it's 20 million. And a sample is actually a pair of numbers. It samples it as a complex number. So you have the real and the imaginary portion. So this is much better. So if we look at this here, what we'll see is there are, so each of these peaks here is where there's a RF energy present in the spectrum. In this case we're looking at the spectrum from 90 megahertz to 110 megahertz. So this is the FM broadcast band. And if we look here we'll see here's a station, here's a station, here's another station. And because of the GPU acceleration you can actually see the colors, the coloring here is telling you effectively where to signal spend the most time. And then down here you can actually see the audio data as it's being modulated. So with FM radio it's frequency modulated so the frequency will vary. If we zoom in on a station, what you can do by tuning to, let's see, which should be good. And let's go to our six megahertz bandwidth, or a sample right there. So if we look in here we can see some of the stations more clearly. And let's see, this 97.7 should be good. One other important thing to note is that you'll typically get what's called a DC offset which is where due to the way the sampling on here, on the radio is done, you'll end up with the, there will be a peak at zero depending because it shifts the frequency down and there's usually some offset there. So just make sure that if you're trying to see something you ignore that effectively. So if we look here you can see here is a radio station. And you can see the voice data that's being modulated, here's another one. FM radio stations are nice because they are really high power so you can see them pretty much anywhere. Some radio stations will have what's called HD radio which I don't see any here that have it. But if they do have HD radio what you'll see is that you'll have the voice data in the middle and then you'll see these two effectively square peaks around the edge and those are digitally modulated audio data and that if you have an HD radio receiver it can demodulate that and give you voice from that so that like HD one, HD two or whatever. And the cool thing is the way it's modulated if you have an old radio as you tune across it it just sounds like static but if you have a radio that can actually pick it up and receive it you'll hear the voice data. So now if we say, let's say you wanna listen to the station at 97.9 megahertz we can go over here and say that our station is at 97.9 megahertz. And now this should work. You need to close this and run. So GNU Radio Companion will take your code and decide it doesn't like it. So, yes, much like other GNU software. So what it does when it works, which I think it will work X Quartz and stuff on a Mac can be pain. See, can we hear this? Okay, so if this works, sample right, center field. I might need to turn up the gain. And this is why software defined radio usually isn't used in commercial applications. It doesn't work. Also, like my fan on my computer is going, okay, here. Let's see. Is the audio on the VGA cable connected to the sound? So no, so I'll just have you listen. Junior, that's a Spanish radio station. So you can do that. Right now it's using much of CPU because that's a lot of work to process all this. Another thing you can do is you can actually demodulate what's called RDS or Radio Data System data. And that is in FM radio. You'll have data that's, once you demodulate the data or the modulated signal, you'll get audio data. Except there's actually a lot more, so human hearing goes from about zero to 20 kilohertz. They transmit about up to 15 kilohertz of audio frequency. Then there's a bunch of other stuff. So in that is the lowest part, zero to 15 kilohertz, is the left plus right audio, so that's mono. And above that you'll have the left channel minus the right channel. The reason they do that is for your radio to receive stereo, it adds them and subtracts them to get the left and right channels. And by using that you can then get stereo, but if you have a really old radio, it just picks up the mono audio. There's also some stuff that will give you information on what the radio station is. And this is called RDS or Radio Data System. And this is how on your radio in your car it says, this is whatever radio station and you're listening to whatever song. This runs and it will. We tune it to that same station and turn up the gain. And so what you see here is that there's actually an slight offset, so we do 0.8, see. Let's try and find another station that might come in better. So when this works, okay, that was a comma. I'm guessing probably to turn up the gain more. So it should be, actually, that's what it is, the antenna. So the problem actually is the same thing I had earlier and that the antenna is set to the wrong thing. I don't usually listen to the radio and I usually really don't do this for reasons like this. No, it was using the, so that's actually how strong FM radio is, instead of using this antenna it was using the other port and that's where you're getting nothing now. So there now I can turn up the gain and this could come in better. So this station doesn't broadcast RDS. And also you, let's see, there a way to see that. That's a great position. GNU Radio is a pain on small screens because apparently according to them, small screens don't actually exist. So you'll end up with like, it's off the bottom and you can't see that part, which is always fun. And this doesn't like, does that work? No, so, let's see. So if I can get this to show it off to the, where you can see it, you can see there at the bottom it shows the, like what station is, I guess I want. I can't remember it, let's see. So if you can move that down, now this should work. And of course the configuration is like here for numbers that you know what all the docs are, right? Okay, this is not helping. Move that down, the other one just needs to be moved up here. GNU Radio Flow Graphs can get quite large. So let's see, put this one down. Now this thing about GNU Radio Companion is it will tell you if there's an error before like everything breaks and it'll usually be fairly helpful. And also you don't need to, it takes care of a bunch of the stuff for you. The interesting thing about GNU Radio is it's actually, while it generates, so here you can see this now. So that worked. So this station doesn't broadcast it. You said 103.104.3, I can type. They do not want gigahertz. If I can find, okay, so here it is. So what you're seeing is this is the data coming in from the station and RDS is a fairly low bit data rate system. I think it only is a few thousand symbols per second or something. But if we look, we can actually view the constellation. And the constellation is effectively it's saying like on the X and Y axis or sometimes it'll just be one axis. This is how the data is being sent and every sample is plotted as a dot. So like if it's AM radio, you'll see one line and it, you'll have dots everywhere it's sampled. In the case of, in that line, we'll present amplitudes. In the case of frequency modulated radio, this would be frequency. I don't remember exactly what RDS uses, but when this is nice, you'll have two clusters of points. In this case, it's not receiving the signal really great. So you're getting kind of this all over, but the idea is you'll get it and then you can look at the other things. This is the, this is the audio. It goes about 15 kilohertz of left plus right. And there's this pilot tone, which tells your radio receiver that it's doing stereo. And then further up on the, and this is an audio frequency now. You'll have other things like there's some other data. This is RDS and then your left minus right audio. And it's done as a double side band audio thing. And then here's your RDS data, which works decently well-ish. So that is one use of software defined radio. Another use for it is you can actually see what's called ADS-B. And ADS-B stands for Automatic Dependent Surveillance Broadcast. And this is used on airplanes too. So it's part of the FAA Next Gen program and it's designed so that instead of just having the airport's radar get radar reflection off the metal body of the plane and then ask the plane's transponder, what are you? The plane will continually broadcast its location, altitude, and airspeed. So you can receive this very easily. You can actually receive it using the, this is an RTL-SDR dongle. And these things are actually quite amazing in what you can receive with them, considering how low cost their construction is. One other nice thing is if you buy one and have a soldering iron, it can be helpful to shorten the antenna lead just so it's not as unruly as it is otherwise. But there's some software called Dump 1090 and that will allow you to do, it's called Dump 1090 because the signal's transmitted on 1090 megahertz. And this will allow you to receive it. If you do dash dash net, it'll allow you to do it over network interface, which you can view when this loads. So this is receiving the data and if once and it sets up a server so you should be able to receive signals once this loads. Actually, oh, that's what it is, right? Dash net. Yeah, it should be 8080. This was working earlier, connecting. So this should work. So when this works, you can see airplanes and where they are. So if you wait, so anyways, what this does when it does work is you'll see actually airplanes on a map if they broadcast their GPS coordinates and you'll then see that you can actually look at where they are, how fast they're going, their airspeed. And the cool thing is that you don't need transmit, which is good because you don't need a license or anything. And also if you can't transmit, it's much harder to get in trouble. There isn't, except for a few things like pagers, there isn't really, you can't really get in trouble for receiving a signal. With radio, you always should make sure that if you're transmitting, you are licensed to transmit and you're transmitting on the right frequency and you aren't doing anything illegal. At scale, there's a ham radio licensing thing, which if you want to get into this, I would advise that you do. And it's generally a good idea to make sure that you know what you're transmitting and where you're transmitting it before you transmit. Using something like a new radio, you can actually do a lot of the stuff all in software and not need to go into hardware unless you actually want to transmit. So some other things you can do with, I'll leave this running and see if this comes up with anything. So there's, so the new radio and a lot of such refined radio, we use what's called complex numbers to sample it, which it's done because it makes the math a lot easier. So for AM radio, what you'll have, they have a waveform and its amplitude will change based on how the signal is modulating. So a very easy way of receiving it is just to kind of average over that signal and do what's called an envelope detector where you say what is the amplitude? The problem with that is though that when you're doing that you then need to be able to, your, the frequency of your signal needs to be high enough that when you average it, you can still hear what you're doing. If you use complex numbers, which it effectively is you have a pair of numbers, you can then you do, where is it? So you can actually, so if you use complex numbers, what it ends up doing is in the radio when it samples it, it mixes the signal by and shifts it down with two sine waves that are out of phase. So one sine wave will have its peak here, the next sine wave will be over 90 degrees. And what it will do is you'll get two different signals from that. So one is called I, which is the in phase or real signal and the other is called Q, which is the imaginary or quadrature signal. It's wonderful that they chose I and Q and I is the real one and when in math, I is the imaginary constant. But it is capital I because that is totally an easy to discern difference. So with complex numbers, what you'll end up happening is when you look at like just the real or complex portion of it, it's effectively looking at the side. So this here is showing a, what's called phase shift key signal which is where you have a sine wave and the amplitude doesn't change, the frequency doesn't change, but what happens is the phase change. So it's effectively like it's going up and down and it shifts over when that happens. So you can look at it here and you can receive that fairly easily. But if you look at the different, like if you effectively change where your real plane is, you then it can go away. So if you look at it from this plane, you don't see that phase change at all. But using math, which is fairly complicated and a pain to understand and Wikipedia is horrible at explaining complex mathematical ideas. You can turn it into a complex number in which the amplitude is actually the distance from the center of the circle. So if this was voice or AM modulated data, you'd look at the distance from the center here and you would see that you'd have this wobbling around here showing when it's closer in its lower amplitude, when it's further out its higher amplitude. For the frequency is represented by how fast the signal goes around the circle. So the faster it is, the higher frequency. So for FM radio, you could then look at how quickly does it rotate around the circle? For phase shift keying, you can look at which direction does it go and when there's a phase shift, that direction changes. So complex numbers make this math a whole lot easier because you aren't dealing with, okay, so if I average out this for AM radio or trying to measure the distance between peaks and FM radio or trying to keep track of the phase as much in phase shift keying, you can just look at it as a complex number. So there are many, many, many other radio modulation systems. AM, FM and phase shift keying are probably the most common ones, but there are many other ones. A common other one you'll see is Gaussian frequency shift keying, which, so frequency shift keying is where you change the frequency of your wire transmitting. So you'll transmit usually a single tone and you'll just vary its frequency really quickly. The Gaussian part is just, it does some shaping of the signal to have it give it better transmission characteristics. When you're transmitting a signal on the RF spectrum, there tends to be a lot of noise and interference in other stuff. One of probably the biggest sources of that is in 2.4 gigahertz, you have Wi-Fi and Bluetooth, along with a bunch of other proprietary RF things, like wireless mouse and whatever. Those can, what? Yes, and they'll also interfere with each other. So they'll end up, see is this, okay there. So what you'll end up wanting to do is design a modulation that's really robust. What is the, so this isn't picking up any planes still. If you have multiple devices connected at once, it can be kind of finicky to get them to all work. The easiest solution is just unplug it. But if you're, so there are all sorts of modulations in another really, really busy portion of the spectrum is 900 megahertz, which it's also in what's called an ISM band or industrial, scientific and medical. And when an ISM band is effectively a, anyone can use this band provided you follow some rules. Those rules are, you're limited by power and a few other things, like there's some limitation on how much of the spectrum you can use it once and whatever. But if we go to the 900 megahertz band, the sample rate, turn up the gain, and I need to set that to the other port, oh TX slash RX, so if we go up to 900 megahertz, so we'll see a whole bunch of stuff. This is actually fairly interesting. So if you see, so what we can see here is there's a whole bunch of stuff. What, so if you look, if you, there's usually digital packet radio stuff in here. This stuff here, I'm guessing is probably interference from something. One thing that's interesting is your display and your computer, because there's often a digital interface. In digital you have a square wave and the square edge of that wave, it effectively goes up to an infinite frequency because when you have any signal can be periodic repeating signal. You can accept it just in that period out to infinity then you can make it any signal. Can be represented by summing a bunch of sine waves at different frequencies and different amplitudes. And a square wave, because it goes up really quickly, how quickly that edge rises determines the maximum frequency of that. Soon like the interface between your laptop and its display, you'll usually get a bunch of, or a signal generated that if you're careful you can actually kind of receive and see what's on your display. It's hard to do and I know someone tried it and they were mediumly successful. They're interesting, so this is probably some noise like that. But if you look here, so up here at around 930, 929 megahertz these are pagers. Down here this is probably some, a lot of the stuff, 900 megahertz is digital modulation so this is something actually, for this shortening the antenna helps because it's higher frequency so you'll end up with shorter wavelengths and you'll want your antenna matched to your wavelengths. So if you look here, this very quick bursty stuff is a digital modulation. It's using what's, it's probably using a technique called spreader, it's a wide band modulation and that it goes from I'd say about five megahertz wide. It does that so if there's a signal in the middle that interferes with it, it's more robust against it. And if you look how it's some very short quick bursts that tells you it's probably digital thing. You'll see there are some, the lighting's not the greatest here, but there are some other bursts here and that's all using this fairly limited of about 20 to 30 megahertz portion of the 900 megahertz spectrum. You have a question? I think so, I'm not entirely familiar with all the spread spectrum stuff. It could be. Direct sequence spread spectrum is a fairly common one I believe. If we go down to about 800 megahertz what we'll see here is more stuff. This is probably a cell tower or does that, yeah, we're around 800. I'm guessing this is a cell tower. They tend to have around, if you tell cell towers around 700, 800 megahertz, I think then like 1,800-ish megahertz. 1.9. If we go further down we can actually see a TV station. TV stations in North America use a modulation scheme called ATSC which stands for, I don't remember what it stands for, but that it's a fairly, what it does is it takes an MPEG transport stream, then modulates it and transits it out RF and then it puts a carrier or a pilot tone that is fairly easy to see. So if we look here, this is, it's also six megahertz wide which makes it fairly easy to identify. So if we look here, this is probably, let's see if we problem-tuned it a bit longer. So over here this is probably a TV station. If we look here, let's turn it up again. So we'll see that here's the pilot tone at 648 megahertz then at six, wait, 654 which is about here, actually wait, that's actually probably not one, let's see. Or is it four megahertz, I can't remember. So there's a whole bunch you can see. On the FCC website you can actually view the licenses for TV stations. One cool thing about ATSC is that the channel number does not correlate to the, California, does not correlate to the, yeah, so there's a virtual channel number which is what you see and then there's a channel it transmits on. So you could have something that's like channel number two but it's actually transmitting on what would be the channel number 38 or whatever. This is done to make licensing and sharing the spectrum easier. See that, should work, I want, I was? Okay, yes, okay. No results. So here you can see a bunch of stations, loads, I'm surprised it doesn't have more. Okay, so you can see that this is on channel five which is, Wikipedia has a nice list, North American television frequencies. If we go down to channel five, that is on 76-ish megahertz. So due to the way the FM, or the broadcast bands have gotten divided up, you have the low channel which is between zero and 14, your channel number is zero to 14 which is everything that, which is VHF or very high frequency. Then you have much higher channels, I think started around 500 megahertz that is UHF or ultra high frequency and that's the rest of it. Let's see, let's see, 12 is, so in this case, it's channel number 12 and their virtual channel isn't filled in. You'll sometimes see, so here you can actually see there's the, yeah, so if we look here, I'm gonna guess this is probably a station at 200 megahertz or let's see. So it can be sometimes hard to tell, ATSC is a very, you can find a station, do you have a strong station near here? Okay, okay, so here, that should be the pilot signal. So what you're seeing here is the, here's the pilot signal which is offset slightly to 210.31 megahertz and then up around here, you're actually, this portion here, you're seeing the actual data that's being transmitted and ATSC, you'll actually see that it's fairly finicky that if I, how wide is it? It's, yeah, six megahertz across the whole thing. So from 210 to 216, except you're getting a bunch of other stuff. So this here actually, what I think, so what this here is, this is the, wait, where? You can't see that, or you can see these little, so this is probably the wireless microphone I'm wearing and it's actually, okay, maybe not. So this is some wireless, okay, I think it's wireless microphone, but what's happening is this isn't what the signal is transmitting on. What you're getting is out of band transmissions and that you either have a, this is either getting interference from it because it's really close, so it's interfering or what you're seeing is that the microphone has some spurs or harmonics, which is, in fact, it's trying to transmit at whatever frequency it's transmitting at, I think, 500 megahertz. Yeah, you're getting a harmonic, so you try and filter it out, but some stuff leaks through. So if you're over there, you won't receive it, but really close, you're receiving it and that's what this probably is. You'll also see there's a bunch of digital bursty packet stuff here that isn't part of ATSC and that's something else. So effectively, RF is a very, it's like being in a bar where everyone's shouting except, and you're trying to have a conversation with someone. This is why you have organizations like the SEC who license it and try and help with this. Don't get them mad at you. If you're transmitting, know where you're transmitting on. Listen first, make sure there's nothing there. And then, when you're transmitting, use the lowest power necessary because that, a person two miles away doesn't need to hear you if you're transmitting in your own house. That's about all. Does anyone have any questions? So right, okay. How large is the slice that we're looking at? So the RF spectrum goes from, depending on how you define RF, a few hundred kilohertz up to hundreds of gigahertz what we're looking at is, I think, 10 megahertz wide. 208 to, yeah, 10 megahertz wide. This radio, the USRP can go up to, I think, 60 megahertz wide. See, yeah, it can do up to 60 megahertz or 54. And that, so right now we're viewing a fairly large portion of the spectrum. These O's here are actually saying there's a buffer overrun in that there was, we're getting more data than we can process, but you're looking from 186 megahertz to 240 megahertz. Depending on what you want, so like FM radio has about, I think like half, or no, 500 kilohertz is about, as wide as it goes, wide band signals like Wi-Fi that's either 20 or 40 megahertz wide. Does anyone have any additional questions? This is the B200, full disclosure, I visited them and they gave it to me. I also have a Blade RF as well. If you wanna see it later, you can come look at it. The USRP, B200 slash B210, the only difference between those is the B200 can receive and transmit as one receive and transmit port or can receive on one frequency and transmit on the other. The B210 has twice, so it can receive on two different frequencies and transmit on two different ones. The Blade RF can receive on one and transmit on another one at the same time. These are what's called full duplex. The Hack RF is half duplex and you can only transmit or receive on one frequency at a time. Is there any other questions anyone might have? Just raise up your hand, I can hand you the mic. Are you licensed? I have a ham radio license, yes. In addition, I'd like to remind everyone don't sue me. I have kind of a non-technical amateur question, but when I move around the house at various times, it interferes with just my FM home radio. And also I notice that occasionally, it seems like at certain points in the room, the hair will stand up on my arm, you know, I swear it happens, I don't know if that makes sense, but can you explain that kind of, what's actually happening in the house when you're getting that type of? I don't know what's actually happening. I'm guessing here standing up sounds more like static electricity than anything. I'm losing reception buildings, which are made of concrete and metal usually, or commercial ones tend to absorb RF fairly well. Humans are bags of water pretty much, which tends to absorb RF well, especially at 2.4 gigahertz. There's also something called multi-path, which is especially common in urban canyons, where you have skyscrapers, and you're down here, a transmitter is wherever, and that the signal will reflect off, so you might get one signal directly from the transmitter. Another signal that bounces off something to you, and then that's like a bunch of reflections or multiple paths, multi-path, and this can cause problems in that you'll end up with multiple versions of the signal that you'll receive and they can interfere. That's what could be happening. I don't really know though, it's probably one of those. Also you could just have something in the way, toward you go there, the signal is too weak. This is 2.4 gigahertz, you're looking at Wi-Fi, so this here is a one Wi-Fi channel. It is 20 megahertz wide. Here's another one. This is probably some proprietary thing. If you look in the, so Bluetooth in Wi-Fi are very interesting. Wi-Fi, it says I'm on this channel, I'm using it, and it'll then say hang on to send something, everyone else be quiet, it sends stuff and it's done. Bluetooth frequency hops around, and it designs if there's interference that goes right through it. Wi-Fi's approach to interference as it resends, Bluetooth just hops away from that fast and that's not a problem. Bluetooth and Wi-Fi can cause problems that Bluetooth will transmit where Wi-Fi is, and because they don't really talk to each other at all, you can end up with some interference between them. Yeah, 2.4 gigahertz can be a very crowded portion of the spectrum as well. Any other questions? The project you talked about for monitoring planes when you call it 1090? Dump 1090. Dump 1090. In addition to that, is there anything else that's comparable to that to monitor anything else whether it be satellites or? So for satellites, the FunCubeDongle Pro Plus is an interesting, it was really designed for like a, to use a downlink from the CubeSat thing. Ballant Sieber, if you look him up, he's done some work on receiving signals from satellites. So for satellites, effectively what you wanna do is either find a signal or find a satellite. Usually you'll wanna get a dish to get better signal quality pointed up there and then you wanna, for that you'll probably wanna buy some filters and a low noise amplifier to put right on the dish to help filter out the signal because the satellite is way, way, way up there and the signal can be fairly weak when it gets to you. As far as I know, there's not like, with satellites, there's not like a, this is software you can use to find all of them. One of the problems with satellites is they don't always have, they aren't always like a, here's everything, all the modulation data for our satellite. So a lot of it can be reverse engineering stuff yourself. All right, do we have any other questions yet? All right, let me get them out here. Hold up, are the tools that you use in this presentation linked from the slides? No, but Google or whatever your preferred open source search engine is will fix that. Yes, I also have a page of references. Lastly, I would like to, so these are, this is the radio data system software that I used. If you just search Google for, let's see, if you search software, software, I don't want to move those slides. So really the software you care about is probably the new radio in GR Osmo SDR and then GQRX. If you're on OSX, you can use Mac ports to install it all for you, except for GQRX which you can just download from, build from source or download. I didn't show that, but you can use it. Then GR, but this is really all you need. Yeah, I'd also like to thank these people. Jared Boone, he did the complex number visualizer thing. Russ Handorf, and actually all these people have helped teach me about software defined radio. Michael Osmond and Dominic Spill have done the, they do the hack RF and then scale for letting me speak here. Any other questions? Anyone? Before we give them a round of applause, I guess. There we go. Excellent.