Hi,
If you want to transmit a stereo program band limited to 15KHz, you could use a standard like APTX as your AD/Compression scheme. Using a 12 bit dual AD and a compression 4:1 you will end up with a 256KBPS. This bit rate would fit in a standard FM channel which has an occupied BW equal to 300KHz even if you used a digital modulation scheme like PCMFM, what would allow you to use a regular broadcasting FM transmitter.
In the receiver end everything would be the same as a regular receiver up to the demodulator output, where you should have a baseband filter, a hard clipper and an APTX decoder to rebuilt the analog L and R channels.
NandoPG
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