[daip] PCAL

[Leonia Kogan]

Jim,

I guesss you think that PCAL uses pulse cal tones. That is not true.
PCAL computes polarization corrections of the antenna feed using the
calibrator with known polarization property. It has nothing to do with 
pulse cal tones.

PCAL averages frequencies of the calibrator signal at each IF. 
That naturally requires flat phase within each IF.

Leonia


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>From owner-daip at kochab.cv.nrao.edu Mon May  7 07:01 MDT 2001
Date: Mon, 7 May 2001 06:51:22 -0600 (MDT)
From: Jim Ulvestad <julvesta at cv3.cv.nrao.edu>
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To: Leonia Kogan <lkogan at cv3.cv.nrao.edu>
cc: daip at cv3.cv.nrao.edu
Subject: [daip] PCAL
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Leonia's comment in CHANGES.DOC says that data should be
phase-calibrated before PCAL.  What does this mean?
PCAL has previously been used to do the delay
calibration for each IF in VLBA observations, and
there is no phase calibration before that (only
the parallactic angle correction).  If I interpret
Leonia's message correctly, he seems to me to be
saying that you have to fringe-fit before
running PCAL, which takes away the whole point of
using the pulse-cals to do the initial delay
calibration in continuum observations.
If you average the pulse-cals in a given IF, then
how do you use them to get delays?

Perhaps I'm being dense or jet-lagged or just plain
misunderstanding the message, but this strikes
me as being a problem.

jim 


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