 theory that amateurs use, I didn't think to bring it today, there's a book the size of a phone book, so at this size it's 3,800 pages and that's just RF, there's another book almost that size for antennas. So it's a very very big field, most people don't need to know even a tiny subset of that, but certainly if you want to start designing products that feels radio, transmitters, amplifiers, that kind of stuff, you need to get into some fairly arcane stuff. Tonight there's no hardware. I'm just going with a quick run through about amateur radio in particular and why that way it's useful and then if time permits I will touch on the two fundamental things that make electronics useful for making radio, how it is we actually make radio waves with electronics. To put it into some sort of perspective there are basically two ways to use what are called intentional transmitters, so I hope I just stuff that happens to admit RF that we don't license like motors and drills and two questions, but things that deliberately transmit signal tend to fall out into a license free and a licensed category. The license free is typically low-powered devices, the industrial sign of the medical, the obvious ones, so Bluetooth, Wi-Fi, garage door openers, ZigBee, wireless microphones, hundreds of different applications operate in some fairly small chunks of spectrum that are available for use without a station license or operator's license at very low power levels. The other is licensed and again these are samples rather than a full list but we all know about radio and TV stations. Mobile network operators are of course now the big one and they are sort of buying larger and larger pieces of spectrum. You also land mobile, typically fleet management type systems, most of those predate mobile phone systems and but they often stay in use because they have characteristics that mobile phones are badly, things like push-to-talk or something rather than push-to-talk instead of calls. Marine is the same thing but for ships and then of course amateurs who have the the interesting added characteristic that at least in theory, that's a good moment, it's the only situation in which you can make your own transmitter and operate it without having it put through regulatory approval. So it's like it is right in the middle of people want to make their own electronics. IDA's answer is it's specifically that it's self-training communication, technical investigations, people who authorize, that is to say licensed and without pecuniary interest. That doesn't mean it can't be related to your profession, in fact a lot of amateurs are competent engineers but it's that you can't be operating a communication service for the purpose of some business specifically. Amateur radio has been around a long time. This year is the centenary year since the first US amateurs were formally licensed. This was not long after radio started being used because amateurs were playing with it and wanted to experiment. This is sort of even prior to the World War II boffin era where guys looking in their garages were inventing things that changed the course of war. It was at this point there were still a lot of people playing with it out of interest rather than in the context of a formal institution, a corporation or university. And so the licensing arrangement and the public service obligations for amateur radio have been around for a century this year. But, sort of roll forward and from 69 when the internet or most strictly speaking ARPANET was created and then selling mobile and then mobile internet and now mobile broadband and new universal penetration, it's like why do it? We now have this omnipresent comms network that's really easy to use, extremely reliable, lots of bandwidth, lots of applications, so why bother? And that actually turns out to be quite complicated. There are many answers. There are a whole lot of different things people do with amateur radio and because it is something you can do with more or less as you wish, people take some regulations, people do a whole range of very different things with it. I didn't find quickly relevant photos for Tibet but Haiti. Same thing, amateurs can walk in, literally walk in with the gear on their back and set up and operate communications infrastructure when there is nothing. In a space where there's no power grid, no phone grid, no buildings, an amateur walking with a pack full of gear and set up a working comms station, they can operate certainly over dozens of kilometers, potentially over thousands, depending upon a number of variables. So these get used in emergency situations to forward messages back and forth between sort of the connected network of the rest of the world and either sort of individuals in need of help or emergency workers who can deploy ahead of the mobile network being recreated or indeed the power network being recreated. Not much good having a working phone if there's no power to the phone towers. So yeah, these are guys in operating in Haiti, these sorts of antennas sort of yell, this was assembled by amateurs, but that's fine, it works. And in this kind of situation, they can bring it up and running fast. They don't need much coordination, although once they're on air they can and do coordinate. And equipment is available for deployment in these situations by various organizations specifically for this kind of problem. Another reason that it's of interest is the project that Jimmy talked about that Harish has a workshop about in South Asia, which is Serval. Serval is the name of this kind of cat. But it's also a project to establish working off internet IP based applications. So the intention is specifically in disaster recovery scenarios where the network is out to be able to build basic called email, chat, file sharing, information sharing type applications. We've got some servers and radio and mobile phones, principally it's why it's, it's phone centric but think Raspberry Pi is an basic radio. And so in this case, you generally do all this stuff on 2.4 gigahertz, which is one of those unlicensed use options. But knowing how to make intelligent use of antennas to make such an effort to work in a physical area, requires some understanding of area. Apologies for the terrible picture. But a nice idea just because of the, how old the amateur service is, is that we have little license spectrum all the way from 2 megahertz, which was considered the, everything that 2 megahertz was considered useless in 1915. So yeah, let the amateurs have it. So literally everything from 2 megahertz all the way to light was strictly speaking available to amateurs. In practice, of course, commercial applications have been found. It usually is a lot of work of amateurs. And so more and more of the spectrum is now in other users, notably mobile phones, but everything else as well. But there are about 20 separate locations between 2 megahertz and 24 gigahertz that are available for amateurs. So they're almost everything that radio can use to be used for amateurs have a slice available to use. Another big one, I figure some electronics porn is appropriate for this, this group. This is some sort of RF amplifier. I assume I slide so quickly that I don't know what sort. But you in general can't build and operate this kind of stuff in most jurisdictions. If you are not operating in and under a manufacturer's experimental license. So if you take your Zigbee and you start building and I'm touching stuff like this, you're breaking door. I don't know about Singapore and Australia, that's $150,000 fine on the first offense. And jail for the second. They're really, really touchy about it. And there's reasons for this whole services that will collide and cause major economic and safety issues if people step outside the rules. And so the issue is more knowing enough about radio theory to even understand the rules. In fact, to get able to license you have to pass two exams. One is the theory and one is the regs. And the problem is the regs are pretty simple, but the language they're written in is impenetrable to most people. So you've got to learn a lot about radio theory in order to understand what the regulations are controlling. Another really big one is power. So the low power device specs that I mentioned earlier, 2.4 gig, generally one gigahertz above, you're allowed to use 100 milliwatts ERP. Won't explain that tonight. At lower frequencies, the 868, which CFOX uses, 900 megahertz, it's used for a similar sort of ZB type stuff and also for mobile phones, very convenient, but they're right next to each other, are about five times that. And in a sort of XKCD, you know, oh, I didn't see over there kind of a way. Oops, just slide. That's what amateurs can do. And that's in Singapore. In the US, it's five times that number. This is enough to roast a chicken. Right. So you need to know what you're doing, because if you start doing this in your neighbors and your antenna isn't set up correctly, you're doing really bad things to your neighbors or yourself. So this is a very large amount of power. And this is, I say, this is in Singapore, where the limits are quite low. But if you're using the ionosphere itself to propagate radio, this is enough to get you almost halfway in the world, almost to New York, depending upon conditions and who's the other end and all that other stuff. So it's an interesting anomaly that this capability still exists in the modern world at all, let alone in Singapore. Most of the amateurs in Singapore who are active are more interested in this than anything else, although increasingly they don't seem to be that active. I tried to put together a list of stuff amateurs do. This is a sampling, although it's probably 80% of what amateurs do. The public service stuff is generally being able to route traffic during emergencies. It's not relevant in some of Singapore, which is extremely dense, very small and unbelievably organized. But if you take Australia or the US, we do these huge open spaces and periodic, certainly US tropical storms, the amateurs actually come up to run, to be available to deal with emergency traffic where phone networks are out on a periodic basis every couple of years. And then certainly in Tibet, Haiti other places where you really can just turn up. I mean, in coordination with emergency guys of course, but without putting emergency workers in the situation, having to wait for networks to get prepared. DX is just long distance operation. And so this is this big thing about using the 3 to 30 megahertz slice to deliver signal through the ionosphere. And so there's refraction, there's multi-hopper ionosphere and there's skip on the ground as well, where signal is being reflected at the upper body of the ionosphere and the ground. So this whole art, but yeah, that's a 300 htxt by itself, explaining all that stuff always. There's four layers of the ionosphere or three depending on what time of day you look. In the US in particular, there are 300,000 licensed amateurs, so the US, the Amur Service in the US is extremely well developed. They'd have an annual field day where they are competitively handling message traffic. And the deal, the rules are, no grid. You've got to be running off batteries solo. You can use petrol power generators, but it's got to be something where you can run in a situation where there's no infrastructure. The running of repeaters is really common to make use of a higher location to be able to use handheld gear to talk to each other. And this is in fact one repeater operating in Singapore, more to come. The repeaters on satellites is about 15 or 18 ammeter satellites, which actually have repeaters on board, and one not ammeter satellite, which also has repeaters on board. Low power is a particular hobby. So yes, we can do 300, but there are guys doing two milliwatts long distance by all kinds of cleverness. It's very tedious and bandwidth is ridiculous. And I'll get to an example of that also. Well, the example is MoonBounce, where it takes you a minute to send a 15 character message and you need an antenna array the size of a small building to do it. So it's a tricky hobby. Meteor scatter. This is getting into the crazy area. As a meteor passes through the atmosphere, it leaves a trail of ironized gas behind it. If you are fast, you can use this to communicate. You can bounce a signal off it. And so the minimum communication is about five messages, three one way and two the other. And so yeah, you've got guys who do this, who are waiting for meteors to appear and they're actually going, hello, yes, signal report, signal report, thank you. It's like, oh my God. So the less ambitious guys use aircraft. There are guys in Sydney and Melbourne, which is right at the limit to what you can do with an aircraft of 30,000 feet, who are seriously using jumbos as effectors. It's fine. It's legal by the time if you look at the numbers, it all works out. The signal is below the noise floor as far as the plane is concerned, as far as the aeronautical areas are concerned. It's fine to buy. Direction finding in fox hunting. I've never done this, I've liked it at some point, is you sort of hide something and then you walk around with Yagi's handheld and find a transmitter, fox. Mountain topping is sort of taking the repeater thing the other way around and sticking yourself into the mountain, which gives a great increase in range and so on and so on and so on. Something I noticed when I was about 26 is a mountain that I visit quite frequently. This is the Australia Canberra Snow Mountains. This is about 160 kilometres. And the only is you can't see this map. There are no mountains in the way. There's a digital repeater on Mount Janini, which is just outside Canberra. And there's this Australia's third ice peak here and nothing in the way. And then there's a wormhole that relays amateur traffic through the internet at the Australian Defence Force Academy. So it should be possible to sit out here in the middle of a UNESCO heritage area and establish an internet connection. Nowadays that's trivial. At the time it was a little more difficult. So that's at the summit. So we carried quite seriously the laptop, the radio, the modem, a giant battery that you can't see, the mast, the antenna, a cable, which the antenna cable is quite heavy, the tent, the gyro, the pings, et cetera. The 160 kilometre section worked, but the wormhole at the Defence Force Academy was broken that weekend and it's a data centre in the Defence Force Academy. Nobody gets in on a weekend. I was only up on the summit for about four hours. So now I'm sort of assuming my interest in amateur radio. I want to communicate ever similar distances, exactly, but with more modern gear to talk to satellites. So a satellite rig for antial operation looks something like this. The antenna that's vertical in this case is the same kind of antenna as what I was using, the two-meter band, 1.4 MHz, and there's a 70 centimetre or 4.3 MHz horizontal. And that's because the repeater in the satellite has receivers and transmitters on two different bands so they don't interfere with each other. So your radio's got to be capable of dealing with both bands, or two radios. Satellites themselves are tiny, so this kind of size. Apart from one satellite in particular, which not only has a repeater on board, it also has astronauts on board, more than half of whom have amateur licenses. So hopefully we'll be able to talk to actual astronauts in orbit sometime later this year. Maybe it'd make a fair, but I haven't yet got my license. I've got a license application in, but it's stuff that's got to happen first. And then, yes, my actual objective is a satellite that's even further away. And this is tough. This is... Particularly because in Singapore we have a very low pallet of news, and so you're dealing with unbelievably weak signals. You take a waterfall diagram, a signal that sounds like noise, and what's coming back from the moon is 30 decibels, or a thousand-fold, a low-bat. So the method of recovering that message is probabilistic. You can do something called message estimation, a bit of DSP that sort of tries, and goes, oh, look, I found one! So, yeah, that's that talk for the day. Very briefly, and I'm a little tight for time, is that for the 20 minutes or the 30 minutes? Yeah, okay, so I'll just slightly inter-Q&A. I wanted to give a sense of, and this is sort of the focus for additional talks and workshops if you guys want to do them, the two fundamental things that make it possible for us to use electronics to make radio waves. So one of them is antennas, and the fact that electricity propagates at no more than the speed of light, even in a bit of copper. And so, if you think about a I think a church organ, rather, forget the electronics for a moment, imagine you've got a 300 hertz tone, which is about an octave below me at the sea, and an organ tube that's closed at both ends and about a meter and a half long. So 300 hertz at the wavelength is one meter, because the sound moves at 300 meters per second. So you've got, it takes one and a half seconds to travel the length of the tube. So you've got a standing wave set up, and you end up, because it's a near multiple, it's a half, the half wave, the quarter wave, it's an even number of quarter wavelengths. You end up with these nodes stable. Once you get to a resonant sound, so think about an organ tube or blowing on a glass or what have you, how it resonates, it resonates when you've got these nodes and innodes in stable positions. The same thing goes on in a radio antenna. The difference is that one, there's a magnetic field involved, and two, the thing moves one million times as fast, 200 million meters per second, instead of 300 meters per second. And so once again, what you're trying to do is set up a resonating device, which is half a wavelength long. In other words, it's this. So you've got in the middle maximum current flow into and out of the two quarter wave sections, and at the end, no current flow. This is like a bunch of people running into and out of a room. You're actually pushing current into here, and you notice that for such a short period of time, that it's exactly at the time that the back of the end of the wire gets filled, you then start sucking it out again. That's resonance, as with the organ tube. So the principle then allows us to create or to detect radio waves as electrons is the antenna. And so the next piece is there happens to be two fields associated with radio waves. So take the what it has horizontal before, make it vertical here. So what we call the electric field also lets up and down this way, because that's where the electrons are moving. You also get a magnetic field, for example the H field that we call white, oscillating at right angles to it. So in this case, the propagation direction is in this going this way. So you've got both an oscillating field this way and an oscillating magnetic field this way. So the field that's produced and the use of the antenna to get from electrons to a magnetic field, the challenge is how we make an oscillator in the first place. Yes, nature's right-handed and well that's going to matter in a moment because so this electric field creates this magnetic field, but as the magnetic field collapses, as big as it's established, it's creating another electric field also at right angles in the opposite direction. So it's depending which way you label the things, natures are the right-hander or left-hander, but yeah if you've got a magnetic field, sorry electric field growing this way, you get a magnetic field growing this way and the fact that every field growing this way is now causing another electric field to grow this way. This is called reactants. So you sort of push electrons into an antenna or a coil and it's pushing back. So this limits the rate at which, on your fire voltage, it limits the rate at which the current flowing through a coil for wire even can increase. It's this fundamental thing that makes radio possible but it also explains why we can build oscillators that are very low energy. So compared to just using a 5.5 timer with a capacitor and a resistor, I assume time was up. The typical approach in radio is to use a capacitor and a coil. So what's going on here is in a capacitor, a capacitor with a little battery. It starts empty, you push current in for a while, the voltage across the plate gradually increases. So this is showing you that as this current progresses, the voltage across is voltage in radio land. The voltage across the capacitor gradually increases behind it. However, the inductor has the reverse characteristic thing that's described. You start to apply voltage to an inductor, the current is delayed because the moment the current starts flowing and thus the electric field moves, a magnetic field begins to form and the formation of that field around the same piece of wire causes an electric field to form which is resisting that growth. It will stabilize and come back to a near zero conductor but it takes time. And so in this case, the voltage curve is this one, the voltage across the inductor is actually leading the current. You raise the voltage across the inductor, it then takes time for the current flowing through the second to increase. We know the current flowing through both components is the same because they're in series. It can't be another way. But something very peculiar is going on with the voltage. The voltage across the whole circuit is this. And yet the voltage across the inductor is higher than the voltage across the whole circuit. So this is 10 volts, this might be 15. And the reason is this is 5 volts but out of phase or negative 5 volts if you want to. And so what goes on? At some point you get to a situation where the reactive components both the capacity of an inductive load are the same. They match. So you end up with something you behave like a resistive load despite having reactive components. That's resonance. That's the point at which. So as with the antenna you've now got the same thing going on inside an electric circuit that these two things actually start to behave very differently once they're at the frequency at which. So if we give an inductor it has a reactance, if we give a frequency of such and such, if we give a capacitor it has a reactance at a frequency of such and such. And it turns out that you can solve a simultaneous equation that for any pair of inductor and capacitor there's a single frequency at which they resonate. And so when you build a circuit like this one, you've got some sort of single generator putting out sine waves and you're playing with the frequency. As you approach the frequency at which the reactance for these two are equal, in other words resonance, the amount of current flowing suddenly increases. I'm not actually infinity, there's a whole other argument for that. But the oddity is that yes the voltage here can be a lot higher or a lot lower than the voltage being supplied. So if you're building a radio receiver, if this is not a single generator but an antenna receiving signals from the moon, this is a extremely efficient way of, I think it's like millions of times as efficient as using a resistor and capacitor amplifier of matching just the signal that you look for. So it's a fundamental pairing right throughout radio for receiving, for filtering, for transmitting that you use the inductor capacitor pair at resonance to give you the ability to decode a signal. This is about the simplest sensible transmitter I can find. There are slightly simple ones but they get complicated to explain. The first detail to notice though is the same thing, the pairing of the inductor and the capacitor. And so in this case it's because they're parallel rather than series, it's the other way around. You know that the voltage is the same because both components cause it has to be. And so what's going on here is that as the magnetic field around the inductor collapses, you get a current flowing because you now have a changing field, so current is induced back the way, that pushes current into the capacitor. At some point this exhaust, this is full and then this more or less becomes collective again and it then begins to charge in the other way. So if you had perfect devices, no resistance, and if you were not injecting or removing any energy, then this would just oscillate continuously, which is mostly machine. You don't have this resistance, this heat, you're taking power out to put into your antenna to transmit. And of course in this case you're bringing a modulated signal in, but what this does do is resonate at a specific frequency. So as with the organ pipe or blowing over a one glass, all the other signal or other frequencies just gets damped and the signal that you're trying to transmit is the one that is able to pass through. I don't know how much sense that may do anyone, but that to me was the most stunning bit of RF electronics. It's like, wait, that's what makes radio work in the first place with electronics. Becoming amateur. So I strongly suggest anyone in Singapore who's planning to do it, at least visit and if not, and perhaps join the Singapore Amateur Radio Transmitters Society, just because it's sensible, particularly in an environment where there are very few amateurs and so for the IDA, where the sort of corner case of weirdos, they have much more time to deal with the telcos. People we deal with are called market access, so the amateurs really are just oh god, so it's crazy amateurs again. So we study theory and rigs, books it and pass the exams. There are two, not that hard, but you've got to learn the theory first. Apply for a license, receive license. Between steps, four and five is a hard to estimate period of time. I may or may not have a license, but I make it there. I hope you have one. Importantly in Singapore, do not attempt to purchase a radio, or transmit it specifically, before you have a license. The good news is the dealers won't sell them to anyway, so it's by the way, but you must have a license ahead of possessing a radio. And then yes, at that point you're on it. I've gone slightly of a plan. Do I have three or four minutes for a couple questions, or am I? Yeah, thank you. Do you come up with questions? Okay. Is it questions? Does this make sense to anyone? We cannot transmit terribly, like you can only listen to any damn. So there seems to have been a change recently. Increasingly, if you buy radios made, well anyway, for amateur use, they actually include a receiver. They'll do everything from 100 kHz to leaders with a scanner. For a long time, Singapore had an absolute hard-nosed refusal to allow the importance of scanners, and for amateurs that was making it difficult to get radios. Sometime in the last three years, that stance has changed. You still, the audience is still pushing pretty hard to ensure that amateurs can only be transmitted by radios that can transmit on amateur bands, but they seem to have relaxed about the receiving. That would suggest to me, and this really is conjecture, but that would suggest to me that whatever it was that was bothering RDA, and I'm going to hazard a guess, that it was a security service or a emergency service still using 100 kHz radio, has now been resolved. I don't know for sure, but I would suggest that those two categories of service have now all finally migrated to the radios, which means that there's little reason to object to receivers. I don't know the fact. I haven't tried to buy a scanner. I'm not sure what happens if you do, but it seems that there's been a change in stance the last few years about receivers. So, maybe. Certainly there are software-defined radios floating around. More of them are receivers than transmitters. People are using them so far, no one has spoken to them. I would suggest that it's, certainly for myself, the stuff I'm doing will be very visible, and so I will be queuing fairly scrupulously to what the law allows, you know, and not doing this stuff without a license, because I'll be publishing designs for what I'm doing and test results. That's not sensible if you're offering outside, but it's, yeah, I have the impression that receivers are now getting, uh, the idea is more relaxed about them. Sure. Each treaty country does its own licensing, and treaty countries are almost every country. I mean North Korean is going to have employer and a license. It's just about everyone in the world. Somalia might be a problem. In general, there's a separate treaty about reciprocal recognition, and there are usually arrangements a bit like driver's licenses that allow you to use a foreign license for a limited time under specific constraints. It is with noting that amateur rules do vary significantly from country to country. There's a sort of broad normative set of frequencies and modes and power levels and procedures, and then each country has its own records. So, yeah, probably yes. You know, in Odie's case, if you have a license, specific license, not just specific, you have a current license at the time that you move to Singapore, then in most cases they'll allow you to do a conversion, although just ask me to set the regulations exam and not the theory exam. When you see that we know projects doing our L transmission, are we doing something criminal? Um, so it depends how you're doing it. Uh, if you are using a ZigBee-type device, no. They're package modules that operate in a controlled way. It's been pointed out that it is possible to bit bash 100 megahertz FM directly out of one of the GPO pins on a Raspberry Pi, for real, and it worked, yes, it did. So the question then becomes, all right, so a little detail that I did skip about, you know, making your electronics. It is a common thing for amateurs to do to make their own radios, except that I learned about two weeks ago that, suppose I'm going to recall, no one has ever attempted to license a homebrew equipment in Singapore. And in Singapore, unlike most countries, amateurs are required to register all their equipment. We fill the same, we use the same forms on the website as the telcos use for their mobile networks, except we're doing one station as a local network. So yeah, they wonder who you are, where you are, what you're doing, and then radio by radio down to serial numbers. And so in theory, we register every piece of equipment that we have that's part of, that comprises the station. And so I said, okay, well, you know, I'm going to do some pretty custom stuff for what I'm going to do. So how do you do homebrew? And the answer was, no one's ever done it. Wow. Or have I licensed it? Right, okay. So not sure how that's going to play, but assume that that obstacle can be overcome, then there would be nothing wrong with an amateur doing the radio by a bit bashing trick. Where you just basically get a bit of wire and twist it around one pin, you know, and transmitting on an amateur band. But, you know, be warned, the band slices that amateurs have available are fairly narrow. And even then, there are often spectral purity requirements far above what's required to stay in band. I figured the actual, I think it's 10 pounds per million or two meters of plant butt, you know, might break it above, which is a fairly tight stand to hit. So you should get a signal out that the odds that you'll be operating inside the little constraints aren't very good. So that's the other difficulty. I suspect the answer is if you're only upsetting other amateurs, then the IDA is not going to pull up. But if you, bear in mind, if you, like 144 MHz has amateurs on it but go down to 100 MHz, which is not that far in RF terms, there's broadcast radio. And many taxi uncles listen to broadcast radio all day. They will complain. So if this is part of why it's important that amateurs have chunks of spectrum all the way, 2 MHz or 1.8 MHz to 24 GHz. Because, yes, some of those frequencies will get through concrete somewhat. But to be fair, if you're communicating with someone else within Singapore, a lot of the time it's going to be easier to to use the mobile network. Well, it's there. The other way you get around it is that you place repeaters at elevated locations. And so then all that's necessary is that both parties have line of sight to the repeater antenna. So you can use small handheld devices and communicate to the repeater. Because, yes, the same multi-buff problems, the same attenuation problems that plague RF in every other context. Setting up Wi-Fi, running 3G, absolutely apply because it's just radio. So voice channels, depending on the mode, anything from 2.5 KHz to about 15. This is amateur marine, land mobile, even avionics, they're all similar size. So the amount of bandwidth they use is about the same. A bit of spectrum they're using will vary depends what they are. A lot of the land mobile licenses for security type applications are, they're just somewhere else in the band. But I mean, so VHF is 30 MHz to 300 MHz. In Singapore we have 12 MHz of that. Of the 270 MHz spectrum, amateurs get 12 MHz, which is a pretty big slice frankly. But, you know, there's another, whatever it is, 258 MHz available for a whole range of other applications. So it's, they're sort of nearby but not the same. That makes buying interesting. You have very strange conversations with dealers. Most of the dealers here sell amateur band gear primarily to Indonesians. So you say, hi, what about a radio fuse in Singapore, do I go on it? You cannot. It's like, what do you mean you can't? No, we just can't. So it's challenging. So M-Sat is a club globally, I guess, that raises funds to build and launch satellites. Yeah, it's not, it's surprisingly easy. The launch is the problem. The launch is about 200 grand for a cube's that. So that's got to come from somewhere. These things only have a service life of a number of years. They're not, they're only about 500 kilometers, so they do brush the atmosphere. They will return. So yeah, I mean, if you're using them regularly, it might perhaps be sensible to join M-Sat and the new A-Juice, but you don't have to, it's just available. Before I sort of get on the floor, what I want to ask you guys is, because this is a huge field and there's different things that might be of interest, is there interest, firstly, in future talks on other pieces of radio and or labs on radio? Is that, okay, I'm seeing nods. Oh wow, okay. I'll take a few, yes. Are there particular things that come to mind immediately as being of interest? Antenna placement for several type applications is an obvious one. Any others that you'd like me to address in future? Being a practical session. Okay, that's a little bit trickier. IDA has a quite specific rule about operating. The only people who are allowed to have someone operate under instruction are education institutions, those actual words, appearing in the recs. So a teacher in a class can instruct and then allow them to operate for any other context. It's not clear that that's even possible. I'm happy to do it. Let me get at least to sort of work through what's going on. What if you move to an ISM band or something? Are you allowed to be registered as an individual instructor? The words in the recs are educational institution, but the, I looked at that went, what? Are you kidding? I suspect it's had the discussion and I will certainly be having a discussion for Make-A-Fair because I'd very much like to be able to... The science and remote beauty testing. Ah, and that might be the answer to the question. We may need an event license for Make-A-Fair anyway, so it might be that we get the science center to apply organizationally and then we have one or more amateurs or volunteers be the civilizing operators at which point that problem gets solved. But yes, for a hands-on session like a lab session in Hackerspace or something, I would love to be able to do it. And so let me start with asking for a little thing, like can we do this for the Make-A-Fair with the science center and then ask for, so could we do the same thing in Hackerspace? It's kind of an institution. So yeah, okay. Any other areas that are of immediate interest or obvious interest to people would be intrigued to either hear or talk about or do a lab on? I don't know, sir. Anything for disaster relief, kind of networking? I don't know if there's also some data network, if there's an interesting topic or if it's more important. Oh, the data network stuff, yeah. Okay, so the driver would be the solving the antenna and RF problem because you're then looking at the rest from the standard radio is an applications problem. And so that's what Harish is looking at with Civil is how to build useful stuff. At that point, that stuff is all just you can do the Raspberry Pi and Wi-Fi. What radio brings to the table is doing intelligent things with antennas and with amplifiers to establish a coverage over some area. But yeah, okay, that sort of stuff it's related to. Can we do useful free radio type stuff that goes on in several German cities using sort of multi-hot Wi-Fi? It would be an interesting experiment, so IDA would kill it. All right. Generally, yeah, so I mentioned the amateur handbook is 1,300 pages. The antenna book that goes with it is only 800 pages. Antennas are the art. And so yeah, it's come to me with a particular question and yes, certainly. Generally, the size of the antenna is a reverse function of the frequency. Antennas are small to go and further and I had 900 megahertz and above. He was equal? Thank you.