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olegkutkov / open-phd-guiding

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SNR value lower in PHD2 than PHD 1.13 #418

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
PHD2 inherited the dark subtraction and SNR calculation code from PHD 1.14.2.

There was a change in PHD1 prior to 1.14.2 that causes the background to be at 
a higher level for the SSAG camera (and perhaps others) given the same light 
and dark frames.

Since SNR in PHD is estimated as peak / mean in the search region, the SNR 
value is lower in 1.14.2 and PHD2.x.  This can prevent PHD2 (and PHD1.14) from 
being able to guide on stars that could have been guided on in PHD1.13, given 
the 3.0 SNR threshold.

We need to fix PHD2 so that
  1) dark subtraction is as effective as it was in PHD1.13, and
  2) PHD2's SNR calculation is valid estimate of true SNR

Original issue reported on code.google.com by andy.gal...@gmail.com on 5 Apr 2015 at 4:54