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I would like to be able to hear a simulation of what the actual radio waves sound like, should I be able to hear them directly. I understand the math of frequency modulation, and am willing to make the required program if none are currently available, but I don't know anything about working with sound files.

I can try changing my speed on the signal to make the output more intelligible. I should clarify: I already know the math; what I don't know is how to use the math on signals in e.g. .mp4 files. I don't care what programming language I need to use, though I prefer GoLang, Python, Java, C#, C++, Pascal, Mathematica. Also, if someone already has a freeware program in which it could be done, I'd try it.

  • see DX7 ... en.wikipedia.org/wiki/Yamaha_DX7. Is sound synthesis by FM modulation what you're looking for ? – audionuma Mar 9 '17 at 11:19
  • @audionuma I am pretty sure this is not what I am looking for. Even if it does what I want (which I doubt), I want to be able to do it on my computer. – Nazgand Mar 9 '17 at 14:36
  • I think I can do it with reference.wolfram.com/language/ref/AudioData.html and Mathematica. – Nazgand Mar 9 '17 at 15:39
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    I don't really get what your asking, you say you know the math and you seem competent with regards to programming languages, so what exactly do you need to know? I'm sure there are like audio ports of python or something you can use. BTW, dropping Radio FM to audible frequencies would just sound like any audible FM. It has a distinct sound/character. – Marc W Mar 9 '17 at 22:06
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    Are you asking how to convert mp3 to PCM? There are posts at stackoverflow on how to decode audio files to normalized PCM, in Java. But mp4 doesn't make sense to me. Doesn't mp4 include visual data--a compression format for videos? I have made a Java FM synthesizer, but it was from scratch not from a library. It isn't that hard to do. The whole proposition (making radio waves audible) doesn't make a whole lot of sense to me. They are too high a frequency to be audible. What is your plan? – Phil Freihofner Mar 11 '17 at 7:59
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Well, you first need to create a mapping from your amplitude to your desired frequency, let's call it f(x(t)). Then your output signal is an accumulation of the phase of the respective frequency, namely cos(integral(tau=0..t,2 pi f(x(tau)) d tau)) .

For FM, f(x(t)) would be a linear function of the form f_0+c*x(t), but your mention of "audible range" would tend to imply more of a logarithmic mapping. Neither make a lot of sense as long as the frequency of the "signal" is in a range similar to the frequency of the "carrier".

  • I can try changing my speed on the signal to make the output more intelligible. I should clarify: I already know the math; what I don't know is how to use the math on signals in e.g. .mp4 files. I don't care what programming language I need to use, though I prefer GoLang, Python, Java, C#, C++, Pascal, Mathematica. Also, if someone already has a freeware program in which it could be done, I'd try it. – Nazgand Mar 8 '17 at 22:20
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You can't put an audible signal as FM onto an audible carrier: the total bandwidth would be quite outside of the range of hearing unless you use a rather shallow modulation width. In which case you'll not be hearing much at all apart from a somewhat unstable whine.

There is a reason that radio FM bands are spaced out in the ultra short wave spectrum.

  • My plan was to modulate The minimum amplitude as the lowest audible sound and the maximum amplitude of the input file to the highest audible sound. I know that it is possible to do, and plan to do it once I figure out how. I do realize that this means 'silence' would be a tone in the center of the audible spectrum. – Nazgand Mar 8 '17 at 11:22
  • Did you mean to write "minimum frequency at the lowest audible frequency and the maximum frequency to the highest audible frequency"? Or are you getting into AM? – Phil Freihofner Mar 11 '17 at 8:01

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