On 20/05/2023 09:12, Martin Lefkowitz wrote:
>
> Here is the screen capture of the Marcus Leech version of the two FM
> demodulate as described here
>
> https://wiki.gnuradio.org/index.php?title=Frequency_Xlating_FIR_Filter
>
> https://github.com/patchvonbraun/wfm_stuff
>
> With a samplerate of 2.4M it uses about 60% of the 4 core I5 I am
> using for this project
>
> If anybody wants the grc pm me.
>
> The other email contains the Zans version of stereo demod.
Your taps for the freq-xlating filters aren't properly specified. They
must be the output of one of the taps-generator
functions--use the Low Pass Filter Taps block.
Further, your desired parameters will lead to a very large filter.
This is mostly controlled by the transition width parameter,
and as that parameter becomes a smaller fraction of the sample-rate,
the filter grows non-linearly. Consider a
"lazier" transition width, and use an FFT filter instead--the FFT
filter structure is more efficient once you have more
than perhaps 30-50 taps.
I haven't touched the "wfm_stuff" code in a long long time, so no
guarantees about anything--including performance.
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