On Dec 10, 2007, at 8:34 PM, Brian Willoughby wrote:
I have never implemented an FSK decoder, but I believe that it should
be possible so long as the bandwidth and frequencies of the modulated
signal do not exceed the Nyquist frequency. If you have a signal
modulated on a MHz carrier, you'll need to shift this signal down to
the audio range. An external receiver would be needed for this.
However, there are certainly FSK schemes which are not modulated at
such high frequencies, and thus you may not need any external
electronics before the audio interface inputs. Just remember that
you'll typically have only about 20 kHz bandwidth. You can have more
if the
...
Oh, the radio receiver is already downshifting the signal. I have
audio, well under 20 kHz. My question was more about the interface to
an AudioUnit: obviously, samples come in, but my AU doesn't produce
samples of audio data out; it produces a bit stream.
Does this fit within the model, or would I end up finding some other
outlet for my data?
The reason an FSK demodulation AU seemed appropriate for this is that
it does take audio data in. Furthermore, it might be preceded by
filters or other DSP.
