Heatmap with unwanted vertical lines

John john at tonebridge.com
Sat Jul 11 17:29:55 UTC 2015


When I use heatmap.py with output from rtl_power I get regularly spaced 
vertical lines that do not appear to be related to any signal.  They 
look they like repeat at the dongle bandwidth (2048000Hz in this case).  
The crop option for rtl_power reduces the presence but I am not sure f 
that is intended by that option.  Even at -c of 70% they are still there 
(see attachment).

Is this because of small bin width?  If I use a larger bin (32k) they 
are still there.  In this case there is no frequency legend along top so 
can't compare if they happen more often.

Are these lines to be expected?


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