Squelch problem in NFM about shinysdr

[kpreid]

This is GNU Radio bug #621 (which I found the same way you did). It is fixed in revision 55645df… (but there has not been a release of GNU Radio since then).

A minimal workaround, if you need one, would be to add gain to the signal just before the quadrature demodulator in basic_demod.py FMDemodulator, like this:

self.connect(
    self,
    self.band_filter_block,
    self.rf_squelch_block,
    blocks.multiply_const_cc(1e6),   # add this line
    self.demod_block)

By inserting the gain at this point, there should be no side effects because it only changes the magnitude, which the demodulator would be ignoring but for the above bug.