Working Narrowband FM examples?

[Nathan Van Ymeren]

Hello,

I am seeking a working NBFM receiver example, as the one on the wiki[0] 
produces unintelligible output.  I am confident that my hardware is functioning 
properly because if I tune to the same frequency (162.525 MHz ) in gqrx, I can 
hear the weather radio broadcasts clearly.  I am on OpenSUSE Tumbleweed, 
running gnuradio 3.8.x with a HackRF One and a standard telescopic antenna.

I have reproduced [0] verbatim except with the following change:  Instead of a 
ZeroMQ source, I am using an osmocom source for my hackrf.  

I’ve also tried adapting the flowgraph from the “SDR with HackRF” tutorial[1], 
which implements a wideband FM receiver in gnuradio, but I wasn’t able to make 
it produce anything resembling speech when I changed it to narrowband FM.

Additionally, I’ve tried a few NOAA weather radio flowgraphs found online but 
most of what I’ve found either didn’t work or else was for an older version of 
gnuradio and thus had errors that I wasn’t able to work around since I am a 
gnuradio novice.

Can anyone recommend a working flowgraph for narrowband FM, ideally something 
simple and working in gnuradio 3.8+?

Thanks,

Nathan

[0] 
https://wiki.gnuradio.org/index.php/Simulation_example:_Narrowband_FM_transceiver#NBFM_receiver
[1] https://greatscottgadgets.com/sdr/1/