Re: Resource issues when trying to record 2 FM broadcast

[Marcus D. Leech]

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.