Re: [Discuss-gnuradio] Averaging FFT output using FIR filters

[cswiger]

On Tue, 8 Mar 2005, James Cooley wrote:

> =============================
> In python, the code to build the flow graph to split, take the fir
> (average over 2in this example), and combine looks like this:
>
>     for i in range(0,fft_size):
>         averagefir = gr.fir_filter_fff(1, [1/2,1/2])
>         fg.connect((separator,i),averagefir)
>         fg.connect(averagefir,(combiner,i))
>
> (BTW, doing the above, in python, is "averagefir" a new instance at
> every iteration as I expect it to be?)
>

Hmmm, that might work but you won't be able to reference a particular
averagefir later. You could use a subscript (maybe, I don't know!).

I just finished something similar, but for filter taps to switch
into an audio filter. The taps are calculated with:

  audio_lpf_x = []
  for co in range(600,3601,100):
    fc=gr.firdes.low_pass(1.0,af_sample_rate,co,300,gr.firdes.WIN_HAMMING)
    audio_lpf_x += [fc]

then audio_lpf_x[0] is the 600hz, [1] is 700hz, etc to [30] is 3600hz.

Once the graph is running I can change audio bw with

    X.set_taps(audio_lpf_x[filter])

--Chuck