[hpsdr] Waterfall Auto Scaling

[Jeremy McDermond]

I'm working on an auto-scaling feature for the waterfall on Heterodyne.  I've graciously taken Alberto's suggestion and scaled the bottom low value to the lower quartile value of the incoming samples.  This seems to work amazingly well.  I'm trying to think about how to do the behavior for the upper end of the range.  I have some code that grabs the highest sample from the buffer and uses it as the maximum value.  I could do something clever with this and have it "decay" like AGC.  I also could just implement a manual control for "dynamic range" that would let the bottom value float, but have a set number of dB for the range of the waterfall colors.  I just wanted to throw it out to folks and see if there was a consensus feeling.  Keep in mind that I don't want to make things too complex by having every single niggly detail configurable.

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Jeremy McDermond (NH6Z)
Xenotropic Systems
mcdermj at xenotropic.com