# QT waterfall sink manual intensity

**URL:** <https://www.ruby-forum.com/t/qt-waterfall-sink-manual-intensity/239401>\
**Category:** GNU Radio\
**Created:** [February 25, 2014, 4:40am UTC](https://www.ruby-forum.com/t/qt-waterfall-sink-manual-intensity/239401 "2014-02-25T04:40:03Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [February 25, 2014, 4:40am UTC](https://www.ruby-forum.com/t/qt-waterfall-sink-manual-intensity/239401/1 "2014-02-25T04:40:03Z")

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Is there way to manually scale the intensity of the QT waterfall sink,  
in other words, set the dynamic range and reference level like the WX  
sink?

Adjusting the time axis with the scroll wheel alters the intensity axis,  
but the actual color values don’t change.

Thanks,  
Lou  
KD4HSO

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**Author:** ![madengr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ec9cab/32.png) [@madengr](https://www.ruby-forum.com/u/madengr)\
**Post date:** [February 25, 2014, 5:30pm UTC](https://www.ruby-forum.com/t/qt-waterfall-sink-manual-intensity/239401/2 "2014-02-25T17:30:24Z")

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On Mon, Feb 24, 2014 at 10:38 PM, Louis B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Is there way to manually scale the intensity of the QT waterfall sink, in other  
> words, set the dynamic range and reference level like the WX sink?
> 
> Adjusting the time axis with the scroll wheel alters the intensity axis, but the  
> actual color values don’t change.
> 
> Thanks,  
> Lou  
> KD4HSO

Just to make sure, are you using the QTGUI “sink” (the one with tabs  
for the different types of plots) or the “waterfall sink” (with /just/  
the waterfall). If the former, there should be two bars for the upper  
and lower intensities that will affect the colors.

If using the waterfall plot directly, we haven’t instrumented the  
min/max from the gui directly (to avoid clutter). However, the object  
does export the set\_intensity\_range(double min, double max) that you  
can use to directly control these.

Alternatively, with this plot, if you middle-click on the mouse, the  
drop-down menu offers an Auto Scale feature that will adjust the  
dynamic range based on the min/max values in the current plot. I’ve  
found that to be the most useful way to control the intensity.

Tom

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<div class="post-metadata">

**Author:** ![madengr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ec9cab/32.png) [@madengr](https://www.ruby-forum.com/u/madengr)\
**Post date:** [February 26, 2014, 4:38am UTC](https://www.ruby-forum.com/t/qt-waterfall-sink-manual-intensity/239401/3 "2014-02-26T04:38:24Z")

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I’m using just the waterfall sink. The spectrum is slightly oversampled  
so I see the decimation filter roll off to -170 dB and the edges, thus  
I’d like to set the intensity minimum at the passband noise floor which  
is up at -100 dB. The auto scale always catches -170 dB at the edges.

I’ll try editing the Python script directly to access the  
set\_intensity\_range(double min, double max) of the object, unless there  
is a way to do it in GRC.

Thanks,  
Lou  
KD4HSO