I have a 40KHz carrier that I want to be able to check for modulation.
The ‘source’ is the audio source in GnuRadio Companion.
I have tried a number of things and nothing seems to work for me.
I have the source, followed by a 40KHz Bandpass filter and a frequency
translating FIR filter block.
The output of the BPF and FIR filters go to separate FFT GUI’s so that I
see what is going on.
What I am trying to implement is the equivalent of the “Span” and
Frequency” functions on a spectrum analyzer.
The Center Frequency is easy, using the Translating FIR block, but I
figure out how to do the Span/Zoom function.
I Google searched and found a couple of SDR’s with this function, but it
appears to be “hard coded”.
Does anybody know how to this in GnuRadio Companion ??