Comments by "Peter S" (@Peter_S_) on "Did Russia's Military Signal Just Respond To Us?" video.

You only need to run your desired image through what is essentially the reverse of a spectrum analyzer. In FM transmissions the carrier frequency is modulated over a small range of bandwidth and that's the width of what you see on the waterfall display. By outputting signal on some frequencies and not on others you can create what is in essence a row pixels represented by frequency bins. This is a very simple task in software when running on DSP hardware, but don't bother trying it manually with pen and paper.
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@deineroehre Exactly.
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Read up on Inverse Fast Fourier Transforms and you'll have all the answers. It's just a spectrograph in revere. To see the data all you need to do is perform a spectrograph to convert the sound to frequency bins. To encode an image, you start with the frequency "bins" and treat them like the pins in a dot matrix printer. Put noise at the frequencies you want pixels and nothing where you want blank. Mix the tones for a whole row together and transmit a line.
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Starting with a Pi and an SDR dongle will allow you to perfect your antenna + filter and/or LNA setup before you upgrade your receiver.
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@jbb-cj1md Calculus gets hairy very quickly but I thought of an easier way to describe it... Have you ever seen 'how to play songs on piano' videos where the played keys scroll up the screen as a series of parallel vertical lines? This is the same, just pushing the notes needed to create a picture.
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@fjb4932 I'm certainly not asking, just saying 'Seabee on a MSC Oceanographic Research vessel in early '70's' makes me think of words like Glomar.
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Are you familiar with NAFO, the North Atlantic Fella Organization? 😂 Search YouTube for 'TVP World NAFO' or 'Bonk vatniks, get medals: Russia irked by NAFO Fellas | Edward Hunter Christie | TVP World'
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These channels have periodic data sent over them. The buzzer stops for a cycle, the data is sent, and the buzzer resumes.
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@jbb-cj1md Try a search for "Canon in C - Johann Pachelbel - Full Speed" including the quotes and the channel PIANOreader came right up with an example. Rather like the scroll from an old style player piano. The principle difference with with the field analogy is that here there is a plow for every line in the field, and all plows operate in parallel with each one represented by a unique note. Any number of notes can be played together to create marks of the desired shape.
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@tripplefives1402 I've been writing FFTs and other DSP code since 1988. Yawn.
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@tripplefives1402 You can stop being a plonker now, if you're able, which I seriously doubt. I said, "Read up on Inverse Fast Fourier Transforms and you'll have all the answers." I didn't say the simplest implementation is X. I'm guessing a lot of people call you pedant under their breath.
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@tripplefives1402 Along the way to the big picture there are innumerable learning aids which describe every aspect as a sub piece in terms which are digestible to the individual at their individual level. If you don't know what the destination is, you'll have a harder time getting there. Once you have a hardware MAC unit, this all becomes rather mundane and is easily accomplished today on Chinese microcontrollers costing less than the pre packaged condiments at your favorite establishment.
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@tripplefives1402 You can stop being a plonker now, if you're able, which I seriously doubt. I said, "Read up on Inverse Fast Fourier Transforms and you'll have all the answers." I didn't say the simplest implementation is X. I'm guessing a lot of people call you pedant under their breath.
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@eTexNerd Being able to spy on your adversaries is good in wartime. Buzzer channels do occasionally stop for a cycle or two where messages are sent. Messages which are most likely military.
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It works like the scroll from a player piano. The picture is made on the scroll and it turns into some number of notes between none and all of them which are played at the same time to create each horizontal line in the waterfall.
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