Re: [Discuss-gnuradio] Spectrum Analysis with FFT plotting

[Sebastiaan Heunis]

Ujala

That looks like an FM signal at DC with another FM signal about 150kHz
away.  The modulating signal of the FM wave in your picture is
probably speech.  If you capture another set of samples using the same
procedure, but with rock/rap/hip hop music, etc. (in other words
anything with a lot of spectral content), you should see a better bell
shape.  The signal should then sit between about -50kHz and 50kHz on
your plot.  FM's maximum frequency deviation is 75KHz either way of
the carrier, so music should give you something close to that (hence
the -50kHz to 50kHz).  Hope this helps.

Regards

Sebastiaan