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I'm a beginner in electronics, have during a 1/4th semester introductory course in electronics the past 2 months covered quite a lot, and everything was presented from simplest "DIY" examples, and also built a lot* practically on breadboards.

I have not covered wireless data transmission much. The conversion from bits to wave sequence is what I do not have an idea about. Is there a good "simplest DIY example" of how to do it? The question can specify frequency modulation as the radio transmission mode, unless some other like AM or PM is much easier to "DIY".

*Low, high, bandpass and resonant filters, transistor amplifiers, AC-to-DC half-wave rectifier converter, instrumentation amplifiers with 400x amplification, analog-to-digital and digital-to-analog converters, flip flops, logical gates from NAND gates, linear power regulators and switching voltage regulator.

helloWorld
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  • https://electronics.stackexchange.com/questions/598767/what-is-the-purpose-of-a-carrier-signal-in-communication-technology/598781#598781 – Andy aka Dec 27 '21 at 18:29
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    in theory fine, but "breadboard" and "RF" is not a combination that easily works: the RF properties of these solderless things are really bad. – Marcus Müller Dec 27 '21 at 18:39
  • Marcus if you are responding to me, I only included examples of my experience in electronics since the question was "broad", and I mentioned it was broad because I have poor understanding in radio transmission, but some in other parts of electronics. – helloWorld Dec 27 '21 at 18:55
  • (so, not asking about building on breadboard, just simple examples) – helloWorld Dec 27 '21 at 18:56

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You could take a look at this discussion of a Forrest M. Mims III design which is a basic amplitude shift keying transmitter: Code transmitter question (original Forrest Mims design)

vir
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  • Looked shallowly at it and managed to get to basic amplitude modulation of a carrier wave by modulating base of transistor with message, https://www.engineersgarage.com/circuit-design-how-to-make-an-amplitude-modulated-wave/, makes sense, simple, thanks. I assume "shift keying" might be same thing but with digital message. – helloWorld Dec 27 '21 at 18:54
  • Is the way the carrier way is filtered out then the resonant frequency of a receiver, i.e. resonant RLC filter? So it excludes (increases impedance) for anything not close to resonant frequency? – helloWorld Dec 27 '21 at 18:59
  • (In my own attempts to reverse engineer how it might work, before I asked here, I had come to that I should use resonant filter at the receiver. Seemed to make sense to distinguish messages by specific senders. But always helps to ask people with more expertise, a bit faster, why cultural evolution relies on imitation and not just thinking :)) – helloWorld Dec 27 '21 at 19:00
  • You do need some sort of filter to selectively "tune in" the frequency of interest. This filters out the carrier wave + modulated information from all the other signals on the channel. RC tank circuits are probably the easiest to implement in the AM band but other methods are preferred nowadays. After that you need an envelope detector to demodulate the signal, which for AM is a diode feeding an RC lowpass filter. – vir Dec 27 '21 at 19:17
  • ok more of a bandpass filter maybe? – helloWorld Dec 27 '21 at 19:18
  • according to this guy resonant filter was popular "initially", https://electronics.stackexchange.com/a/178626/301512, he does not go on to what is popular now – helloWorld Dec 27 '21 at 19:20
  • Yes, it's a bandpass filter feeding into a lowpass filter. – vir Dec 27 '21 at 19:27
  • and the reason bandpass filter is preferred is because it is easier to vary a resistor than a capacitor/inductor, right? – helloWorld Dec 27 '21 at 19:28
  • @helloWorld: Judging from your comments here, I suggest you study radio transmitters and receivers in general, before worrying about handling data over radio. Much of the basic design of radio transmitters and receivers for AM or FM audio transmission will apply to radios used for data transmission. – Peter Bennett Dec 27 '21 at 19:30
  • @PeterBennett and I politely thank you for that. my learning curve is very fast though, so I covered a lot since this question was asked. and I am appreciative of the two individuals who contributed content. – helloWorld Dec 27 '21 at 19:31
  • No, you'd use a variable capacitor/fixed inductor or variable inductor/fixed capacitor for the LC tank circuit. A bandpass filter is mandatory at the RF stage to filter out stations/noise above *and* below the band of interest. – vir Dec 27 '21 at 19:34
  • ok those can be varied too. – helloWorld Dec 27 '21 at 19:35