Hello everyone and welcome to this tutorial about RF transmission. We're going to be learning about RF links, building a circuit, and more importantly perhaps discussing the theory of how it is that, you know, a bit of code, a message gets transmitted from one of these transmitters to one of these receivers. And that's a very important process because it's everywhere in our lives. Your mobile phone works on this principle. Your radio and your car, the satellite transmissions for both, you know, satellite channels or satellite phones. And it's something that's rather simple. For the basis of it is we generate electromagnetic waves. Electronic waves are everywhere. The light is electromagnetic radiation. So sun bays us in electromagnetism. We ourselves reflect it around and all it really is is charges. So electrons generally, although you could have positive charges do the same thing, are bouncing up and down or being shuttled forward and backward. Now this happens inside like atoms when electrons jump up and down from shells or you can make it happen like with oscillating electric current. So an example of like how I could generate light if I was Superman would be out of my hand like this at you, but instead of like doing it a couple of times a second, I do it 400 trillion times a second. In which case you'd see red light coming from where my hand is. And if I did it at like seven, it'd probably be purple light. So if it's that simple, if we create electromagnetic waves simply by shuttling charges forward and backward, then creating electromagnetic transmissions should be pretty easy. And I've got a diagram on the board here of what effectively goes on. So this here looks like an electric motor and it could be a common AC motor. All we do here is we could get charges to be aligned in one way than another way. So effectively we've got some plus charge over here, some minus charge and the electric field goes from plus to minus. But then we can switch it around and have pluses down there, minuses up there. Then we change the direction of our field to plus and minus. And if we do this all the time, effectively what we're doing as time goes on is creating electric fields that go up down. So these are electric field and electric field is the vector. You don't need to know what a vector is. But so all you get is this kind of wave of propagating electric field that go up and down. And some of your guessed it, but what this equates to is like a sinusoidal wave. So if we start up, we'll go down, then up, then down, then up, then down, then up, down, up. We join these and there's our basic electric magnetic wave. So from the other side, we're at the build of advice that looks really similar to our motor over there. We would be able to capture this wave and reproduce it. So if we could do something like similar land, similar dimensions, and it goes through a variable capacitor and then into some kind of an inductor and on the other side, we'd have another inductor. This would affect the Libyan amp. And so what you would get here is this electric field arranging electrons in here and driving them exactly the same way that these guys would drive them. So you have maybe sometimes hundreds of kilometers away, a signal going out in these waves like this. And another circuit similar to the one that transmitted them, picking up that signal, amplifying it, and translating these guys into pictures or sounds or whatever. And the next question you probably logically have is how does this wave carry information? Well, that's where letters like AM and FM come in. So AM would be amplitude modification. And amplitude modification works a little like this. You essentially take these waves and you lower their amplitudes. So when you lower an amplitude of a wave, that becomes a zero. That sucks. So if you lower an amplitude of a wave, that becomes a zero, which would make this wave 1 and that wave 1. You've also heard of FM. FM works a little like this. If you get a wave tightly bunched up, that's a one. Lusely is a zero, tightly bunched up is a one. Lus is a zero, tightly bunched up is a one. So it goes like one zero, one zero. So effectively, what we can do in this end is modify these waves a little bit so that our antenna can pick it up and then we can translate this modified wave into the chain of zeros and ones. And at the end of the day, any message that we send via digital circuits is simply going to be a bunch of zeros and ones, which is read by a program that reinterprets that into computer code, data, and so on. In this particular circuit, it uses something like something called O-O-K, which is on of king. On of king is very, very similar to AM actually. So it effectively has little tiny waves for zeros and big tall waves for ones. And unlike AM, I think on of king uses square waves. So it's actually going to look like, but it's it's effectively the same thing. So what else is there to know? Oh yeah. So the only complicated part of this, the only part of this that's actually difficult that I myself can safely say I don't really understand happens at this stage. As I said, radio frequencies are big with us. These waves are absolutely everywhere and they interfere with each other all the time. So if this very simple circuit that you could see, technically a message sends from one pin is replicated in another pin. If I was to try to read that message straight away, as it's replicated, I would get a useless circuit because there would be too much noise. So all of this is without mathematical algorithms that compute them, not very useful. Right here, I can call this a black box. Right here is where mathematical geniuses come up with all kinds of esoteric mats and equations to process these waves that are then put into programs. Some of these are even adaptive. So you send an initial test signal and then an algorithm here is created by the computer that will filter out all the noise to find a signal. So yeah, this bit is fairly advanced and this is why when we build our Dueno circuits, we're going to be using a library and that's what the library does. It filters through the noise and yeah, that's it. That's how radio waves are transmitted. I hope you found it interesting. Now let's go to circuit.