# QT GUI Frequency Sink and real inputs labels are wrong for FFT length != 1024

**URL:** <https://www.ruby-forum.com/t/qt-gui-frequency-sink-and-real-inputs-labels-are-wrong-for-fft-length-1024/234291>\
**Category:** GNU Radio\
**Created:** [February 21, 2015, 9:31am UTC](https://www.ruby-forum.com/t/qt-gui-frequency-sink-and-real-inputs-labels-are-wrong-for-fft-length-1024/234291 "2015-02-21T09:31:38Z")\
**Posts on this page:** 3\
**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:** [February 21, 2015, 9:31am UTC](https://www.ruby-forum.com/t/qt-gui-frequency-sink-and-real-inputs-labels-are-wrong-for-fft-length-1024/234291/1 "2015-02-21T09:31:38Z")

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If one selects real input on a QT GUI Frequency sink, and also selects  
half-width, and also has an FFT size != 1024, then the X-axis labels are  
wrong.

If using an FFT length of 1024, the X axis labels proceed from 0 to  
bandwidth/2, as one might expect. I tried playing with the “center  
frequency”  
parameter to make the labels make sense, but I couldn’t find a setting  
that made it better…

v3.7.6.1-89-gc990e825

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**Author:** ![Marcus\_DSLeech](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/74df32/32.png) [@Marcus\_DSLeech](https://www.ruby-forum.com/u/Marcus_DSLeech)\
**Post date:** [February 21, 2015, 4:44pm UTC](https://www.ruby-forum.com/t/qt-gui-frequency-sink-and-real-inputs-labels-are-wrong-for-fft-length-1024/234291/2 "2015-02-21T16:44:45Z")

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On 02/21/2015 09:30 AM, Marcus D. Leech wrote:

> If one selects real input on a QT GUI Frequency sink, and also selects  
> half-width, and also has an FFT size != 1024, then the X-axis labels are  
> wrong.
> 
> If using an FFT length of 1024, the X axis labels proceed from 0 to  
> bandwidth/2, as one might expect. I tried playing with the “center  
> frequency”  
> parameter to make the labels make sense, but I couldn’t find a setting  
> that made it better…

Thanks,

can you submit this to the issue tracker please?

M

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<div class="post-metadata">

**Author:** ![Marcus\_DSLeech](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/74df32/32.png) [@Marcus\_DSLeech](https://www.ruby-forum.com/u/Marcus_DSLeech)\
**Post date:** [February 21, 2015, 5:12pm UTC](https://www.ruby-forum.com/t/qt-gui-frequency-sink-and-real-inputs-labels-are-wrong-for-fft-length-1024/234291/3 "2015-02-21T17:12:53Z")

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On 02/21/2015 10:43 AM, Martin B. wrote:

> Thanks,
> 
> can you submit this to the issue tracker please?
> 
> M
> 
> * * *
> 
> 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)  
> Done #767