[daip] [!7226]: AIPS - strange scaling of visibility amps & weights w/ DOBAND=1

[Michael Bietenholz]

Michael Bietenholz updated #7226
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              Status: Open (was: Closed)

strange scaling of visibility amps & weights w/ DOBAND=1
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           Ticket ID: 7226
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7226
           Full Name: Michael Bietenholz
               Email: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Open
            Priority: Default
      Template Group: Default
             Created: 08 September 2015 05:34 PM
             Updated: 16 September 2015 04:59 PM



I still don't get it:

1) On that little test data set, plotting the BP amplitudes using POSSM I get that the average amplitude over all channels for IF5 for ant 3 (EB) is 0.82 or so.  For ant 10 its around 0.95.   So if weights scale by these averages, the weight should decrease by about (0.82*0.95)**2 or 0.61x on DOBAND=1 over all of IF5, but in actual fact, the weights decrease by ~10x upon DOBAND=1.

2) Since the BP channel gains vary over more than an order of magnitude (not atypical) form the edge to the center, shouldn't the BP-calibrated weights by correspondingly channel dependent, ie. much larger weights for the central channels, and low weights for the edge channels where response is low? [I know the upshot of this is "just toss the edge channels", but shouldn't the calibrated weights actually reflect the channel-dependent gain scaling?]

3) I notice that with DOCALI= -1, DOBAND +1 *does* change the visibility amplitudes but not the weights (whereas with DOCALI = +1, it changes both).  Shouldn't it either change both vis.amplitudes and weights or neither?

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