Re: NBFM (Was: AM on sBITX?)
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I/Q is one way. Here is a simpler way:
1. The signal is essentially AC.
2. Mark the exact time at which the signal transits from positive to negative.
3. This measures the time period of every crest and trough of the signal. 4. When the signal frequency is low, the time periods are lengthier. When the signal frequency is higher, the time period is smaller. 5. The time period is our demodulated signal. - f
The frequency differentiation method would be able to approximate the phase difference by using consecutive I samples. But the demod product would probably be pretty crappy at best.
I think that the transform method should at least be able to simulate a phased Q sample which may be a bit better as a starting point. I messed with this a while ago when I was offloading a synthetic IQ stream to SDRAngel.
it almost worked, but I lost interest in the challenge..?
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