musings on developing digital RF signal
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The classic FLDIGI approach seems to be:
- generate sound in software on computer
- use D/A converter (sound card) to creat?analog signal
- leverage modulator?in transceiver to produce AFSK signal
I notice that there are a few transceivers, for example:
-?
which:
- detect the frequency of the analog tone
- apply direct FSK modulation of the transceiver: ?they adjust the frequency of the local RF unit?to encode the tones
- this works only for single tone modems
In principle, since the tone structure for a given modem modulation?is known (that is what we feed the PC to develop?the analog signal) we can use this as a fourier transform and then use an inverse fourier transform to produce the RF signal directly.
Has this been done before?
How much surgery?would be required on FLDIGI to implement?some version?of this?
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