Re: [Discuss-gnuradio] FM SCA

[Matthew Ettus]

On Sat, 2002-02-23 at 05:36, Johnathan Corgan wrote:
> What does an SCA sub-carrier look like?  I am in San Jose; I have a
> AR8200 with a nifty spectrum analyzer that might help identify other
> local stations.


If you are looking at un-demodded spectrum  (i.e. RF on a spec analyzer)
it looks like a slight bump in the spectrum at 67kHz away from the
carrier.

If you are looking at demodded spectrum (i.e. on the audio spectrum
analyzer), then it looks kind of like a square bump in the spectrum
centered at 67kHz.  SCA is FM modulated on the main FM.  FM on FM...

Of course if your receiver filters the demodded FM before you can see
it, then it will have filtered out anything higher than about 18kHz, and
you won't see it.

Matt