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Smooth calibration solutions using GPR [WIP] #149

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landmanbester
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This seems to be working apart from some weirdness with the phase smoothing that I cant really explain. I get really weird results when smoothing the phases while specifying a reference antenna. The reason I though this would be useful is because there seems to be more physical structure in the solutions when setting a reference antenna. Here are the ML solutions without a reference antenna for example

new_corr0_scan0_phase

and here they are with the reference antenna specified (surprising?)

test_corr0_scan0_phase

Clearly, in the latter case, there is some physical trend that we pick up by eye i.e. quick variation in time and slow variation in frequency. I thought it would be useful to exploit this when manually specifying the hyper-parameters but for some reason I can't yet fathom that breaks the smoother (conjugate gradient does not converge and gives weird results). If I smooth the raw (but unwrapped) phases and specify the reference antenna only for plotting purposes I get a very sensible reconstruction and no failures (conjugate gradient always converges)

norefant_corr0_scan0_phase

At this stage I have no idea why this happens but at least the smoothing seems to be working. For reference here are the ML amplitudes

new_corr0_scan0_abs

and the smoothed version

norefant_corr0_scan0_abs

Compared to the phases, smoothing the amplitudes is a lot more stable. I suppose this is because jhjinv is actually a lower bound on the variance of the amplitudes whereas it's just a thumb suck for the phases.

JSKenyon and others added 30 commits July 15, 2021 14:52
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Has this PR been superseded by #311 @landmanbester?

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Indeed. Sorry forgot I had this one open

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