Re: Working Narrowband FM examples?

[Mike Markowski]

Nathan,

When I was refreshing my gnuradio awareness - I hesitate to use the word 
"skills" :-)  - I ran through the official tutorials and modified them 
as needed to work with a usrp b210.  On the page

   https://udel.edu/~mm/gr/

about halfway down is the title "Gnuradio Official Tutorials" with the 
link "Here are my versions" where you'll find nbfm.grc.  It's very 
simple, using filter/squelch/NBFM Receive block and runs here on grc 
3.8.2.0, a promising sign.

Hope it's useful,
Mike

On 8/3/21 2:40 AM, Nathan Van Ymeren wrote:
> 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/