Usage of keep_one_in_n in fftsink_nongl

Dear All,
I am exploring the file because i want to modify it to
the sensing method of my project. in the fft_sink_c class, there is a
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
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
if i want to remove this block? because this block make my sensing speed
extremely slow…

best regards,

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sample_rate/fft_size/N = fft_rate

N = sample_rate/fft_size/fft_rate

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

If you tell 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.