[evlatests] Curious correlator problem

[Vivek Dhawan]

This subband is handled by baseline board B103-b-1 = BB2038, in
the vci file it is in quad2, pair4, and used in your case in a
'stack-by-2' configuration to make 4 pol-products, 128channels.

7.5% data loss in one subband. I cannot explain the particular
pattern of baselines affected.

The problem is believed to be not in the board itself (which has
been swapped out more than once) but in a cross-bar or backplane
connection. We have decided to live with such (occasional) issues,
rather than cut out that pair entirely and fly with 63.

On Thu, December 22, 2022 11:50, Bryan Butler wrote:
|
| Project TLOW0002.  Observed 2022-12-13 07:30-15:29.  SB ID 43076911; EB
| ID 43093617.  Script and VCI at:
| /home/mchost/evla/scripts/ost/2022/12/662TLOW0002A if you need them.
|
| 	-Bryan
|
|
| Vivek Dhawan via evlatests wrote on 12/22/22 11:36:
|> clearly some bad boards or parts thereof - there are some known issues.
|>
|> what is the obs SB number, date etc.
|>
|> On 12/22/22 11:31, Rick Perley via evlatests wrote:
|>> In my most recent 'lunacy' observation (taken 13 December, at P-band),
|>> I have found that a number of correlations, in spectral window 5 only,
|>> are not present in the data.  Presumably were 'pure zero'
|>> correlations, and removed in the download.
|>>
|>> For the following baselines, all four correlations are absent, for the
|>> entire observation -- but only in SPW05.  All other spectral windows
|>> are complete.
|>>
|>> ea04 x ea 08 through 21.
|>>
|>> ea 17 x ea17, 10, and 22
|>>
|>> ea 21 x ea06 and 11
|>>
|>> ea27 x ea05, 13 and 19
|>>
|>> ea23 x ea26.
|>>
|>> Is there an explanation?
|>>
|>> Rick
|>>
|>>
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|>
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