[evlatests] Software time Maarch 8

[Rick Perley]

    I loaded Barry's test data, and noted the following:

    1) The data headers look fine to me. 

    2) Antennas 7, 9, 14, and 28 were very weak on all IFs throughout 
the time period 17:46 to 19:00, and I flagged them out. 

    3) Antenna 17 started off o.k., but disappeared a few minutes in -- 
taken out for servicing?  (I fill with all flags off, so I can't 
discriminate between causes). 

    4) All phases were excellent!  No drops, spins, jumps, or any other 
phenomena which cannot be attributed to normal atmospheric phenomena or 
to uncompensated long-term drifts. 

    5) Amplitudes are interesting ...

       a) There were two basic states for all antennas -- one high and 
one low.  The high state was associated with 20 second integration, the 
low state with 10 second integration.  Power is conserved, so this 
difference is clearly a normalization issue.  (That is, the CALIB 
amplitudes are down by sqrt(2) when the integration is halved). 

       b) Within each of the two amplitude states, there are periodic 
drops in amplitude, separated by a few minutes.  The drop amplitudes are 
twice as great in the 10-second integration than in the 20-second 
integration, so the cause is of much shorter duration than either.  For 
most antennas, drops are 'single' (they occur on only All four IFs of a 
given antenna drop at the same time, but each antenna has its own drop 
pattern.  (That is, they all drop, but rarely at the same time). 
    Some antennas' drop pattern is different than that of the majority.  
Antennas 6, 10, 22, 25, and 27 all show 'double drops' when in the 
10-second averaging regime -- drops have two different amplitudes, one 
much larger than the others.  These same antennas also have many more 
drops, and they don't show the nearly perfect rhythm shown by the others. 

    c) Otherwise, amplitudes are very stable, with no unusual effects 
(on the resolution scale I'm using here).  Perhaps when the drops are 
gone, and the amplitudes appropriately  normalized, I'll see more subtle 
effects. 

    I have plots of all the above, for those needing visual accompaniment. 



Barry Clark wrote:
> Things went fairly smoothly with the transition to the Modcomp free system.
> There were two fairly minor bugs.  Data is being written to the standard 
> archive. 
>  
> Ran with 12 MHz bandwidth continuum mode for an hour.  Data reducers
> Rick, Vivek, or Gustaaf, please have a look at things.  In particular,
> look for missing integrations, unusual glitches in amplitude or phase,
> whether scan header information is at least reasonable if not correct,
> whether u,v values are reasonable, whether Tsys is reasonable.  Time
> when we where not mucking with the system, approximately 17:48 to 18:55.
> Feel free to look at other times, but don't get too upset if things are
> unreasonable.
>  
> Several antennas initially were not fringing, probably due to a bad
> parameter somewhere:  11, 28, 14, 7, 9.  Eventually found most of them 
> hiding in delay space.   
>  
> Tried running the standard pointing file.  The antennas were at least 
> wiggling, though problems prevented Telcal from solving for the pointing 
> (problems found but not corrected during the test time). 
>  
> Spend a good deal of time setting delays.  This is a hard slog with 
> the current version of the delay software.  But I got most of the delays 
> set for IF A at X band.  (Except for antennas 23 and 24, which were  
> being worked on, 11, which I never found, and 7, which I got rather
> confused about.)
>  
> Switching back to Modcomp control went without a hitch.
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