findppm should find the center, not the bottom edge, when analysing a flat signal

[khaytsus]

If we're analysing a perfectly flat top signal (some digital, or overloaded front end) we should attempt to find the edges and from that deduct the middle. Signals like NOAA, unless severely overloading the front end of the SDR (gain too high, etc) this error should be minimal or non-existant. However, using like a pager signal or a cellular tower, this might be an actual issue.

However, how far does one go with this? If the signal is 2MHz wide and perfectly flat; with the exception of one spot that's slightly higher, that spot will be the best signal, therefore used. Some additional averaging would have to be used to fix that specific scenario, which IMO is overcomplicating it. Use stable signals that have a peak with reasonable gain.