Re: [Discuss-gnuradio] bins osmocom_spectrum_sense

[Kyeong Su Shin]

To whom it may concern:

I don't know osmocom_spectrum_sense well enough to answer this, but I believe that the purpose of the overlapping is to remove aliasing and the filter roll-off. If that is the case, you must drop from the both side, not from one side (assuming symmetrical filter). 

Regarding the size of the dropped bins, I believe Sylvain Munaut's explanation is correct (12.5% from both side).

Regards,

Kyeong Su Shin

On Wed, Jan 25, 2017 at 12:38 AM, Sylvain Munaut <address@hidden> wrote:

> Does anyone know why the first and last 25% of FFT bins are discarded? I am
> talking about the following lines of code:
>
> line 267: bin_start = int(tb.fft_size * ((1 - 0.75) / 2))
> line 277: bin_stop = int(tb.fft_size - bin_start)

Read that code again ... it discards the first and last 12.5% ... so
that it discards 25% in total.


Cheers,

   Sylvain

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