I am looking at FM radio receiver designs others have created with gnuradio. There are a couple of signals questions I have after looking at these designs.
The source (e.g. rtl-sdr) samples at a high rate, for example 2.4M samples/second. After this the signal is decimated by 4 or 5 times. Why is that? Since the hardware samples > 2*highest frequency of the signal (music), why not just use that? Also, what is the relationship between the WBFM receiver 'quadrature rate' and the sampling rate?
Finally, low pass filter blocks include a decimation parameter. Is this the same as decimation in the resampler block?