# Wx gui FFT sink missing peaks

**URL:** <https://www.ruby-forum.com/t/wx-gui-fft-sink-missing-peaks/236389>\
**Category:** GNU Radio\
**Created:** [August 30, 2013, 6:03pm UTC](https://www.ruby-forum.com/t/wx-gui-fft-sink-missing-peaks/236389 "2013-08-30T18:03:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [August 30, 2013, 6:03pm UTC](https://www.ruby-forum.com/t/wx-gui-fft-sink-missing-peaks/236389/1 "2013-08-30T18:03:07Z")

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Hi all,

i am for a long time experiencing (possible) problem with wx gui FFT  
sink.  
Namely, i have receiver implemented in usrp1 and transmitter which sends  
signal regularly every minute. I receive corect packets and everything,  
but  
the problem is i can’t see the spectrum of the received signal. I  
selected  
option peak hold, and peak is catched very rarely.  
Is this problem with parameters setup or some kind of malfunction of  
this  
block?

Thanks,

---

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**Author:** ![Nemanja\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/7bcc69/32.png) [@Nemanja\_S](https://www.ruby-forum.com/u/Nemanja_S)\
**Post date:** [August 30, 2013, 6:25pm UTC](https://www.ruby-forum.com/t/wx-gui-fft-sink-missing-peaks/236389/2 "2013-08-30T18:25:20Z")

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On 08/30/2013 12:01 PM, Nemanja S. wrote:

> Thanks,
> 
> –  
> Nemanja Savić
> 
> * * *
> 
> Discuss-gnuradio mailing list  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)  
> If your transmission is very short, the FFT may not catch it. The FFT  
> display in Gnu Radio does a fair amount of decimation-by-windows, which  
> means  
> that it throws away a lot of the time-domain “chunks” that would  
> otherwise be processed, in order to attain the desired display-rate.