Re: [Discuss-gnuradio] usage of keep_one_in_n in fftsink_nongl

[Josh Blum]

sample_rate/fft_size/N = fft_rate

N = sample_rate/fft_size/fft_rate

The fftsink_nongl.py wants to decimate the stream of fft vectors by N to 
achieve fft rate (aka frames per second).

If you tell fftsink_nongl.py a sample rate that is greater than your 
actual sample rate, then N will be too large, and the frame rate will be 
very slow.


-Josh


adib_sairi wrote:
> Dear All,
> I am exploring the fftsink_nongl.py file because i want to modify it to be
> the sensing method of my project. in the fft_sink_c class, there is a signal
> processing block call keep_one_in_n. I think that this block is use to
> slowing down the sampling of the spectrum sense, am I correct? if i remove
> this block from the flow graph, the output value will be unexpected
> (unreliable). can any one tell me what is actually happen? what did i need
> if i want to remove this block? because this block make my sensing speed
> extremely slow.. 
>
> best regards,
> Adib