[daip] [!8252]: AIPS - RLDLY: output SN-table phases not consistent with delays (DOIFS=1)

[Eric Greisen]

Eric Greisen updated #8252
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       Staff (Owner): Eric Greisen (was: -- Unassigned --)
              Status: Closed (was: Open)
                 Due: - Cleared - (was: 08 April 2016 02:55 PM)

RLDLY: output SN-table phases not consistent with delays (DOIFS=1)
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           Ticket ID: 8252
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/8252
           Full Name: Michael Bietenholz
               Email: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Closed
            Priority: Default
      Template Group: Default
             Created: 05 April 2016 12:59 PM
             Updated: 06 April 2016 05:20 PM



I studied things more deeply in the case that I have.

The phases are indeed delay*Delta F.  I was confused because
the delays were large enough that the Delta phase was 439 and 971
degrees.  The correction for the 2 pi's made it look like the increments
were 79 and -109.  The phases in the code really are computed with
a phase at the first IF of the group plus a Delta F times the delay.

In my case 9.5ns * 128 MHz * 360 degrees is 439.1 degrees between IFs
and the other 21.07ns yields 970.9 degrees between IFs.  So it looked like
79.1 and -109.1 which is confusing but right.

I don't know why you are having less than desirable results with your
data, but with this strong source (3C286 at L band) the results are 
really quite good.

Cheers

Eric Greisen




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