 That's sort of survey who's in the room apart from the Hackware folks. You're all undergrads safe that in what fields What is that in? The engineering The engineering Conside Canicle engineering any other fields? Okay Okay, and anyone who's not doing engineering of any sort Okay, great. Excellent. That means most of this makes some sense So You're per the description. This is a Talking oh sit down Talking demonstration by example that the ground station operation For at least some kind of satellite isn't all that difficult There's an amount of fiddly mechanical electronic software that's not involved But it's not necessarily the case that you have to tie yourself to Either a commercial facility or go through the process of getting a university to Offline setting up a ground station. So there's a on top of the health building. I believe there's a UHF Groundstation for a the CQT guys. We have a couple satellites Helmet so that they went through that process and getting up on that roof is hard That means physically hard let alone The engineering work and all the other work has to do to make that possible So the point here is you don't actually need to do that that with much less gear you can fix all right so That's in a row. Just that's not my partner in fact. I can't I've got space Well, there's a few next to it and the single lab authority It's a difficult discussion at first but fairly quickly like oh, yeah, okay, that's fine You can use this anytime so it's I won't go much into that but because of Land availability problems in Singapore. This is a permanent problem that Putting up antennas of different sorts. There's always someone has this need to have a discussion There's someone who's going to be all my life. That's you're gonna get me trouble So part of what I'm doing is also Gently pushing and helping various bureaucracies to make it normal to set up antennas and operate in public The slides are there you have that will appear in the talk if you wish Feel free to photograph if you like the slide will be on mine, so So in sort of context this is a radio I know something We've heard of it how many in the room have how many others have heard of a radio or have some idea what it is Blank okay fine. So this is a I guess a practice a set of practices and a licensing arrangement that has been operating for almost a century In fact what sparked it was a miscommunication after the sinking of a Titanic There was a miss on your message a bunch of reporters reported that no lives are lost and then it turned out that that wasn't true And so suddenly the press wanted to blame someone and so the amateurs were an appropriate target at that point Licensing came into play Have to be licensed have to identify themselves and can only operate in frequencies that are designated to use But it's actually it's if you like tinkling with stuff And you want to do so with more than with radio more than what you can do with ISM band radio gear So you've got like Wi-Fi or Bluetooth or that sort of stuff you're limited to the tens or hundreds of little watts You certainly can't do much on Oh broad divisions Interference by lights and motors doesn't make some problem But it makes a turn who's generally break into low power devices ISM and here Which are last this on you Mr. Steady Licence free so things you can do to transmit. I guess it was without a license Go to door winners Wi-Fi Bluetooth that sort of stuff, but you your power If your license is not complete, but roughly boardcasters telcos Private mobile systems but for land C&A and amateurs And what differs for amateurs is that what you required the password of answers when doing exam Consequently, you have an amount of freedom to DOI to build an important No one in Singapore has yet built their own radio, so I'm about to make a fair next month So that's part of the issue It's not just it's a license service. It's also a license service that allows you to build and operate radios without listening theory third-party engineering involved in inspecting before you go in there Where's these other that the marina of a mobile land level tend to be controlled by manufacturing controls and Broadcasters telcos tend to acquire an interview before the stations can go online That's In the 90th century broadcast radio started for real in the early 20th Intense nine say the mobile and 79 mobile internet mid 90s and the last decade it turns out We're looking at now 5g which isn't faster and Satellite clusters hundreds of satellites that then do blanket coverage for it's something to be The latitude puzzle of the entire planet. So there's that sort of beg the question. Why would you do this? And so the purpose this is ideas handbook or the ideas and I make this like But similar language is used in almost every jurisdiction It's a little bit like the rationale for make your activity except that relates specifically to communication systems So it's stuff you're doing for your own interest your own education and not to make money So these other things assume that you're In practice that means an incredible range of things Public service not so relevant here because simple regents and constant work is complete But in places like the US and Australia the spaces involved are too large So both simply cannot cover the entire space. So if you're holding Cycle event or running event out of some enormous distance in the US in like desert conditions in US, Australia You're far outside my network coverage. So if you want communications for event organizer, they might be going to do their own Landmobile set up or part of the amateur club and arrange comes that way. So that's one of the issues Another variant of that is what happened in Puerto Rico few years ago. The hurricane it was specially violent that the Cell tower is physically gone Michael phones useless if there's nothing to talk to and of course if they lost Cons and power and roads in thanks to that. That's a real problem. The red cross goes in and they can't communicate They can't talk to the red cross ask the American way really to call for and get 50 volunteers to go and do two week tours at various of the hospitals What is running in Puerto Rico to allow there to be some minimal comms while they waited for the roads to get fixed So the pen the power comes to come in and fix the ballot works. And then the top of coming to fix the So that's a special case of public service. It's only once it's there's been a formal involvement Disaster that's cable that's something that I was okay This is what this operation is interesting one. It's one that I was invented it's the use of the atmosphere as a harder factor or a factor a bit like lenses in glasses you can do the different radiant all irons to the electron electrons in the arms here provide Enough gradient difference to allow signals at a particular frequency range to be Reflected or affected and so I was used this to communicate Maritime users used to do it not so much the month We're here in the city areas. That's not very convenient We sort of handle rails for talk of that things so I was put up repeaters on the tops of tall buildings All the extreme form of that is buildings that are very very high and very fast moving satellites That's been going on since the beginning of space race there are amateurs working for one of the contractors who is doing the Corona program which is about a hundred launches for the CIA and they need it balanced Pail it has to be regularly symmetric but rotation is a medical otherwise the lockup can't function So you have to put ballast to deal with the you've got the camera and all that stuff and you've asked it So yes, one of the engineers said oh ballast you say Here's a ballast. I made my garage So that that was I forget that might have been December 61 but that was Oscar one went up. He was just a beacon, but like we've been under here in space almost What power is sort of the inverse of DX it's operating in some cases in a milliwatt range over thousands of kilometers That's extraordinary difficult By the fun Moonbouncy is precisely what it sounds like. He's absolutely absurd. There's a half million kilometer for the thousand-kilometer round trip Plus the fact that the moon is not a totally good reflector. And so the losses are Very weak civil mode Highly balloons if you're putting a camera in a balloon and you want to recover it after bursts You don't want to rely on network because your communication module won't come into range until Maybe a second or two before impact and if it fails to associate with the network and send a location pack it fast before Keep the ground then you won't be able to recover it So there are Groups people who use to attach to how to balloons as always a camera a very lightweight transmitter It's just transmitting continuously on and on the frequency where it is and it is here like this to just pack it So that when you yeah, you lose it at some point on the way down This is in food for but you can travel it Because you don't need to lose communication at any point This descent from the stratosphere to the ground Meosphere is also matters of sounds as a megal pathos through the other sphere it disturbs the Layers of ionized gas and so creates a gradient you can actually use the Activated trail behind it for maybe five or ten seconds to reflect So this crazy to the same thing with the aircraft Behind the aircraft itself Distances involve the power levels below what's relevant for the aircraft My behavior The extra finding approximating this sort of recreational activity with radio and now poppings and I enjoy doing which involves what it sounds like Hiking here up to the top of the mountain That's useful for range for really good low a low angle entry to the atmosphere No cutter and often on mountain tops. No interference. So you'll see this be very Very What will operate with it isn't there as it Operate where it doesn't exist particularly desert areas and and will this areas DIY electronics if you start playing with the content of your phone And high power again, you can't use on the ball phone hundreds of watts Mentioned and sir This is something where in a single hop you can do anything up to that three thousand kilometers On there was a hundred watts with a ten-meter high for value in tube A little bit of a top-up in March year. We're talking to stations in Portland, Oregon literally the other side of the planet So that's perhaps ten bounces the ionosphere in the oceans But that requires in ten is that it can be a ten-meter high in terms of a petro In the urban areas walkie-talkies and repeaters on hills or high buildings and all mass This is the same idea as my phone is minus Of course, yes, push that up. You don't kill me this you have that Ideally you have it at 36,000 kilometers at which point this happens that's meaning that the rotational period is the same As the time that takes the earth to do one full rotation if you use a sun centric or sun earth one Central coordinate system. That's 24 hours. If you use a galaxy centric coordinate system. That's 23 hours and 36 minutes The terms that you're all day familiar to anyone in this room No, it's Thomas. Okay just We think in terms of a 24-hour day because our Frame of reference moves during the year As the earth moves around the Sun, the frame of reference is moving and so in fact, it's only if you're looking at a Star of constellation rising at 90 m tonight Tomorrow night, it will rise at 856 because the Galaxy is moving with us We'll measure it. This is only useful if you can afford to get a satellite up to 36,000 kilometers That's quite costly Particularly compared to say like 500 people like all the CubeSat stuff that people doing tends to be around In which case your satellite will cross the sky in many minutes Whereas this this way is sort of This is sounds like a great visualization of reality is this So No So to give you a sense of What's going on? This is all the active or project satellites and we're all that either carry on with a traffic or Beking on a number of frequency So it's fairly popular third comment. It's not likely to be purely transparent to be given Purchasing what alive because my battery status my temperature from a course line and so this is a real time visualization of where as you can see the Two or three kind of a single other driving. That's unusual Other times I'd have an hour between This is a thing called deep predict. It takes data gathered by NASA and NOAAD To get back where satellites are partly to communicate with them and partly to avoid collisions collisions with the orbiting devices Extremely energetic and then but the data is made public. So This is so this tool if you both wake up it out, but also to control the Interrotator and the limits Very briefly, I will not be getting into different Chicago side In order to describe an orbit Need six parameters So it's not if you first the orbit orbits aren't generally circulates. You need an exit to be Describe the shape of the orbit Secondly Korea's length is not so in particular to the Pivot against the reference plane. The reference plane is the the ecliptic, which is where the plane which plants or the sun will serve at the center of the galaxy and they have the same plane And it's sort of the growth of your life is star in the areas constellation So that sort of gives you the starting point The plane of the orbit is To the respect of that this is not a sort of So you have a parameter called the longitude of the ascending node the place where it climbs to the plane you need the idea that perhaps this is a That way The rest is complicated, but you end up needing six planets to describe I'll point out just to give you sense of how all this stuff is These are four Derrits of the model that are used The major rewrite was into Fortran 4 NASA has had to know since the 60s where the spacecraft are And so this is a continuation. There's never been a break So the all of a sudden surround its use uses these same models albeit not actually in Fortran You're really Which contains dozens of pages of differential That explains how the thing works more practically you just get a lot What's intriguing about it is that it's observed by norad and published by a corporation of NASA But a change thing is going to be to privatize it But this back also who is part of the organization that produces that from the first place got a license to just publicly distribute it So despite the fact that was never sort of formalism in the way It's just a guy who's been part of the program for decades And it's permission to give away Without sign which we rely on all this software. He was looking at automatically downloads his version of the What are they why they call to an illness? This is yeah This is an Asian punch that and this is one way Interpreting these is that a bike this way that brings a character So if you would bring this this would obviously occupy one line on a page Just try that and all that requires two lights Us two line alert It's very compact. This is to be in the space the breakdown is That's the each of the satellites. It's in the database as a number But I says it's 2.544 This is an unclassified element, which probably isn't a big surprise humans The difference means that the piece of the ISS that's described is the design model model the first model Basically was launched in 1998. It was the 67th launch during that year. And it's the first Satellite from that launch quite what happens with the newer clusters of satellites that launch dozens of satellites Like more than 26. I don't know. I've not looked but that's what the a is basically the first piece of that launch The mess the rest of just that brown it's tried E-pop and a couple of liberties a drag Fact that keep to deal with atmospheric lag. So I'd like to do gradually slowing down over a period of years For that I get to fire They had thought about its sensibility even at this point But there is no other format has ever been agreed Yes, we can describe the next format of it comes to be but that's subject sums Nothing else. It's horrible. It's something other than they felt the need to Describe the number of rotations per day in H just for places. There's no space before the orbit number Time of the year I think the crisis formed 56,000 Again, what happens when it crosses a hundred thousand? I'm not sure but that's still Oh Basically tell it where you are when it is and they will tell you what's rising over the next hour And given a particular satellite most usefully What has an angle what's in a thing? Do you need to? The road control is simply itself Connect to a port and about one seconds in the message that is P mean position and as a thing or as anything on new line There's nothing to it. It's very stupid. They do knows commands. Let's see if we're off moving So we'll wait for it to finish carrying out the previous man, which would take a minute And then it'll ignore it in December For a workshop in June, I actually produced a simulator If you want to play with it feel free This will actually give you an in-browser representation of where the thing is You can then sort of talk to it. It's the point was to allow a bunch of workshop participants to build their own controllers With a similar before we went outside and did it for real and We get to two of the prisons were successful in giving the point of real satellites and Have ready to adapt So how to do it you can certainly do it free-hand The problem with that is you having to point the antenna and rotate it and operate the radio and log and maybe look at a Tracking application all the same time, which I found a bit overwhelming. So my mission solution was find a friend That's over the confusing building pick By subject solution. However, oops Okay, who's to build the Take off my hands completely the following to across the sky One of the problems or the initial problems is that cameras have lots of chip in general They do not have good attitude control or indeed any So the antennas orientation with respect to you changes the whole time and so okay, hey fix that problem This is with that one solution is to use Stubbock antennas. So this is not all the duration. I've managed with the boom behind Usually it's to attend to the boom in between and the corresponding Sections of the antenna are right here. So the key is they're the same front to back Distance and then between them in the cable harness that connects to the radio. You place a quarter wave length of coax What it does is transforms to linear antennas that lighteners into a circular The reason that is useful is that it matte The QFA says the same someone asked about quarterly is it's they're doing the same thing But it means that other than in the dead spot when the antenna element when the seller position is such that it's pointing an internet element at you, so off the ends of Callaway for the idea doesn't know there's no There's no meaningful Distribution So the sub-lives come to a point where it's Pointing straight down or straight at you. They're stuck in a mullet. There's nothing to do that Every other orientation the two antennas at right angles plus the timing harness means that it will maintain a fairly uniform Sensitivity you lose 3db or 50% of your energy doing so. So there's a there's a price But you gain consistency Whatever orientation Communication can occur so long as it isn't enough Right building things you can have a little over like but it's fairly straightforward These are visiting robotics parts like what from the US supplier sadly all the US measures But yeah two motors one to do the the azimuth the compass direction and one to do the the elevation so These are simple DC motors with reduction gears This is a And so with the plastic years out over and they just Gear the And then there's a Controller that works up which way So this is a sort of cheap straightforward way of working out which way is that this pointing Where I developed another one. I'd use a word linker this design was Anybody else like it build it, but there's some problems with this It doesn't deal with any conditions very well You've got a bit limited if you haven't aligned it correctly if I have Zero degrees is is about 15 degrees off Particular any of the sides and that means a little bit of killing to get it to zero So there's this I mean it does the job, but it's Right cable house, so there's a couple things going on here These the two end cables are the same way Their lengths don't matter. The only important fact is that they are the same length as each other One goes to each antenna in a right angle pair The middle in the middle is a quarter wavelength at the frequency that's relevant So for the shorter elements, which are in the amateur 70 something about about 450 megabits this is Long a bit less for the longer ones. It's about the same. It was two different houses That provides the quarter wave offset that then turns the two linear antennas into the combined But there's another problem the antennas have a 50-ohm chargers impedance Electrical guys, do you know what chargers impedance means? Okay But you can't 250 antennas in parallel and you've got 25 ohm mode Well, now you have a problem because you feed that into a 50-ohm radio and you are reflecting a large fraction of the power I think it's your part of the power being affected to that cause of losses middle effect back and forth But a lot of it will end up heating up the coax Not particularly though nothing you're losing signal in both directions. We've become less sensitive on the receive side Turning what we don't get power into nothing more hitting the wires So what you need is a way to transform 25 ohms from the antenna here to 50 ohms for the radio So the next quarter wave trick is that a quarter wave for coax will transform almost any impedance to almost any impedance This is voodoo. I accept that it is true. I've looked at the maths. I don't understand it But it works. It works reliably. It's used for all kinds of things by others if you think of decades So what you need is a good quarter wave Coax whose impedance Is the square root of the product in between things as you're trying to match So if you're trying to match 50 to 25 What you need is 37 and a half ohm coax That's all very well good except that you can't buy 37 and a half ohm coax But you can buy 75 ohm coax So if you put two bits of quarter wave 75 ohm coax in parallel, you'll have a quarter wave of 37 and a half ohm coax So what you're seeing is the quarter wave section in the middle to the phasing and a pair of quarter wave sections of slightly thicker coax 75 to 50 that match the impedance between power and antennas and the radio And so that's for the 77mm and then the same set up with longer pieces for tuning up This is yet another problem the This setup because of the potentiometer is only capable of a 360 degree Asthma which sounds fine except that you're not trying to point it just one direction If you have 360 degrees of asthma, that's a 90 of fallation you can point in any direction But you want to follow the satellite across the sky And you need to provide fairly enough emotion. So the idea here is that the the blue line is the satellite's track And the red line is the point where the tracker Lost contact with you could no longer keep up and it follows for a while and then when it reaches its end stop It hasn't been turned around And that might take two minutes And so apparently next you've lost a chunk of your transit So the solution to this problem is to know before the pass Whether it crosses north across the south And turn the thing around There's actually a switch from the the controller that says For if you've flipped it around so that zero is south you flip the switch and the firmware knows to subtract 180 from all the hundreds so that It's awkward, but it's all There are some others there's something resembling gimbal lock It's not quite the same, but it's a similar problem for very high paths or for a lot of past things are easy The azimuth is progressing uniformly and the zenith goes sort of gently up and gently down For a very high pass you get into a situation where The azimuth is that way And then quite suddenly it needs to be over there And so you get to 90 degrees and then suddenly the the zenith stops changing because now it's going to spend in two minutes Turning for a minute and a half turning 180 degrees and then descent Don't have a good solution Passes high enough to be a problem are rare And in practice because the beam width for the antenna is something like 45 60 degrees It's it's reasonably forgiving if I was feeling virtuous. I would do the work to to Convert an overhead pass and the pass that was 10 degrees off And then it would mean the azimuth was moved early enough to prevent the problem but Oh, I have no feedback. This is a problem with the design. I didn't design the board The serial it's just a rst32 serial port, but it only has received data And ground it has no transmit data. It has no even though the controller knows Where the motors are there is physically no path To tell the the host computer that's controlling it We are so there's no way to Work out what's happening while you're going you've got to make you've got to decide up front what you're going to do And just tell it again workable Just Right you haven't given one of the problems Now the next is Doppler So an ambulance goes past or an unquantifiable with a boombox the pitch changes. It's Doppler shift So that's been fast enough that Doppler shift materially affects The radio frequency at least on UHF And VHF the difference is small enough that the radio will just go And if an receiver uses a facebook loop and it will just It'll cut But at VHF a 430 megahertz The change is large enough That the receiver will just give up So you've actually got to adjust the receive frequency during the the pass The people in the program that I showed you earlier is capable of doing that You know that a total range of radios and we'll send commands and two radios at once if you want one for transplant and one for reception That's just one of the list of things you've got to deal with The next is head and transmitter You're only using the satellite in the first place because you cannot hear the other guy directly So now you have a problem. You've both talked to a satellite at the same time with the same input frequency And there's no time to name multiple places with them like a wi-fi to control It's just two human beings with transmit buttons So what you actually do or expected to do is is operate two radios at the same time That you receive edge running while you're transmitting So you get to hear what the satellite hears If you happen to conflict with them while you'll hear that Rather than just normally when you're talking you can't hear what's going on So full relax is the ideal approach, but very few commercial values do it So in practice you use two radios I think you can do this if you can find the radio, but I simply couldn't find one that I am gay with aware of And consequently I just gave up. I'll just use two cheaper radios That would be just a feedback risk that the receiver will hear the transmitter And so the solution to that problem is to use two different bands So that you get good separation between the transmitter and receiver And that's the reason for the antenna having two completely different sets of elements Look there on different bands and they're at right angles So you can be pushing five watts into either the hf or your hf And the receiver on the other one will not be swapped Five watts is a lot of power And there's millimeters between the developments or senders And yet with the elements at the right angle and with the frequency separated by that three to one That's enough for a receiver to complete the function And so that trade-off gets designed immediately to the satellites themselves But it's quite common to have a vhf uhf split specifically to the solvents problem To a loud full device operation I don't know if that went too far or too deep At this point I think it'll stop And invite questions How much of this makes sense? Questions, comments? Do you choose the length of the rods and the angle that the distances can meet the rods? That's a very well studied problem The short answer is both those as is from a couple of users Those are in fact arrow shafts The enemy shafts are made for arrows It's arrow antenna So they just take things from that purpose and sell them as... I mean they cut them and add screws and stuff But sell them as mechanics But the design of it is fairly well understood problem And there are sort of papers and calculations around to make these decisions If you want to sit down and study how it works Do so, the physics is reasonably simple Because it's a very simple system But in general you just take a calculator and punch in I want this frequency, this many elements At least as much gain What do I need? Now do you ever work best at this or do you use other things? You can So someone asked about the use of quadrifolia antennas So a fairly common option is to use the QFHs Which is a... It's four helixes But the big benefit is you don't have to... It's got a very broad pattern But it tends to split the ground and overhead Which is good because you minimize sensitivity to local difference But not perfectly It's got some holes in the sensitivity But the really great strength of it is you don't have to point it You just stick it up and it works That suffers from a lack of sensitivity Inefficient use of transmitter power Because you're spreading it everywhere Rather than focusing it Which means you need the power And I'm like... Oh right, so portable gear in Singapore You currently use more than five watts of transmitter power You've got a little bit of room to double the effective power By having three on the algae But that's it And so a QFH... But you use a QFH for a base station Perhaps that up anyway And at that point okay, you're waiting for power Using 25 watts to the five That's fine The problem with that remains the overhead pluses The QFH has a sort of nice panking pattern But it has a null overhead So high parts are supplied So you know, there's trade-offs And it's there Further, you know, the awesome... Parts are just like the fun of playing with electronics And the kind of positions that makes that work So there's a little bit of overkill for what I do with Others... Stunned silence over here You know? I just kind of mentioned that That the instrument of the algae without the main... Will make it somehow circularly polarized Yes Why is there still a loss in the... That's what happens When you convert from major circular You are personally giving up Yes, and I want to understand the loss If you are using a linearly polarized antenna To receive R-H-C-P signal But if you practically recognize Satellarly polarized antenna Shouldn't there be a loss from the receiver? For example, you've just made exactly the point It's effectively... So what do you call that? It's really too linear in tennis Okay So, for there to be no loss What you would need is... Is it two sine waves? I don't think what it is But I think it's a pair... If you add a pair of sine waves, they're out of sync No, I can't... No, I can't really... Sorry But the point is when you... If that's... Theta and that's gang Got it, my brain's hobble But if that's the angle between the... This is simple What it ends up occurring is When you add the two curves together You have a problem So it's not... If you have a real... If you have an actual helix Then it does what you expect When you have a pair of linear polarized antennas It's not But when you combine those Right, yes But that's not so much that It's that what's happening up front That you are remaining... You are in reality more sensitive In some directions and less sensitive to others And maybe there's a better way to say it If you're adding these two together You're not getting this What you're getting is... All that around you It's not uniformly sensitive And that translates into... An average of what's going to be lost Okay, okay, I didn't know Sorry, you know But it doesn't matter You've got a radio that's like a... It's sensitive at minus 100 dB Even in walkie-talkies it's sensitive without minus 80 The loss of 50 dB isn't in here or there And it's common You lose more in the reflection that can get a cable harness So... But yeah, if you... The other is to make a helical antenna The difficult... The problem with doing that Is that you're locked into one interpretation of the other And there are in fact some satellites That have helical antennas So that for those cases you've been off with a linear antenna If you've got this set up for right hand And the station you're talking to has a... The satellite you're talking to has a left-hand antenna Then of course you've got... You're down like... Something like 30 dB Then you start to have a problem And so that's why there are actually two... The two two pieces are helpful Because they can jump from one to the other And in fact I've got a preamp The preamp for use on the receive side That actually has two inputs in the relay And so you can in fact... Immediately for those satellites Which do in fact have circular antennas You can switch live Without having to go out and sort of... Re-cable the antenna But that's... Yeah, if you look at ground stations that use helical antennas They have two One clockwise and one anticlockwise So you... You're damned if you're doing it You're damned if you're doing it You're damned if you're doing it You're damned if you're doing it You're damned if you're doing it But they solve the 3D problem Because they really are Well, with respect to circular When they're talking to a linear antenna Of course they're 3D down So there's... But again, it's not a lot It's not something worth optimizing for There's so many other losses involved The difference between the path loss For a satellite near the horizon And for a satellite in the head It's something like 20 to a bit So you'll pull 15 maybe So it's like okay We're down to 3DB Which means the first five degrees of the... First 10 degrees maybe of the... Of the pass We're below the right threshold Okay Not too much of that Okay Thank you No one else? This was crystal clear And everyone understood everything Oh, completely incomprehensible One more naive person Ash, you have a question If we can receive signals easily With a program system Can we also then send signals Yes, so it works exactly the same way And the thinking behind the two radios That one is receiving and one is transmitting And that's the port of the two bands That you transmit as a... Transmission receiver on different bands Some satellites have VHF up and UHF down Some have UHF up and VHF down Some have lower UHF up and high UHF or S-band down But it's very common to have this Specifically so you can debate But you... It's not... In some places, no one would be too fussed about it In this country it's strictly speaking You shouldn't be operating a receiver without a license anyway But if you've got... If you're licensed for receiving Then you're perfectly fit to transmit As long as you're operating under the usual... Under the rules I believe it can make sense of the data you receive So a lot of this is a voice Of the 20 odd that I heard on my map there A good 8 have working voice transport It's really voice repeaters Just FM And so the interaction is nothing more complicated Than a pair of walkie-talkies Plug into the cable harnesses But a good number of them have digital A fair number use Morse code for their beginning In fact, when I did the workshop The JSConf in June Where I had developers driving They had not heard Morse code before And when they... When they acquired Either the antenna was for the point at the right place This is... Effectively known or whatever Suddenly I recognized that I'm pointing my way Because I can hear... I didn't have the Doppler correction On the machine controls I was doing it by hand And that's... Of course, I knew what I was listening for So I just kept that audible But participants had never ever heard Morse code It's some sort of funky break beat Oh, yeah, sort of But yes, a fair number use Digital modes called X25 It's an amateur version of X25 Which made Ballsense in the 90s Perhaps that makes today It's a narrowband digital mode That will work in particular Hoots wide or 12 kilo Hoots wide FM channels Because again, cheap walkie talkies Will do... Or cheap radios will do that The software for doing it Is built into civil versions of Linux There are Windows applications That'll do it And there's a bunch of stuff built on top of that So things like Winlink radio This is more HF than VHF or DOHF Because there's a bunch of digital modes that are used for email Sort of SMS with complicated gear But very long range Yes, there's a bunch of digital modes that have it as use And mostly they will document it So sure Okay, cool I'll wrap at this point