[evlatests] Fast dump results

[Rick Perley]

    It is useful, from time to time, to observe a while in 'fast dump' 
mode (0.417 second integration), to see if any odd 'features' appear.  
There was a spare 30 minutes of dynamic time last night, so I observed 
3C286 at 6cm.    The data were filled as correlation coefficients. 

    All operational antennas were working very well on all IFs.  A 
number of minor items were noted, and are listed here for the record:

    1) SSDs (Short Shallow Drops -- single 0.416 second integrations low 
by ~15% in amplitude) are in abundance on some antennas.  These always 
occur on both polarizations of a given IFpair, but are independent 
between the two IFpairs.  There is no phase effect whatever.  In case 
the following is useful, I note that:
    a) Antennas on which the SSDs are in abundance (~1% of all 
records):  1, 4, and 11 (on both IF pairs for all three), and 17BD. 
    b) Antennas on which the SSDs are completely absent:  5AC, 13BD, 14 
and 16 (both pairs), 17AC, 18BD, 19BD, 21BD and 25 BD. 
    c) My recollection is that antennas 14 and 16 have *never* shown the 
SSD behavior. 

    2) Antenna 21 was late getting on source, but the data were 
prematurely flagged as good (a few seconds worth).  No other flagging 
issues were found. 

    3) 24A has a curious 1% repeating ramp-like correlation variation -- 
the period is about 2 minutes.  10C has a similar effect, but more 
sinusoid in appearance, with the same 1% amplitude.  (Yes, I'm really 
digging deep to find something to complain about ...)

    4) The listed Tsys values for most EVLA antennas are clearly wrong 
(too high) by factors of 2 to 3.  This must be so, as the derived SEFDs 
are all good, so the antennas have full sensitivity.  EVLA antennas 
which are off by a factor of two or more are:  1, 4, 5, 11, 17, 19, 21, 
25 and 26.  All four IFs are wrong in all cases.  The recorded Tcals 
must be wrong.  Can somebody check to see if the new values are in the 
appropriate database? 

    5) The phase behavior, for all antennas and IFs, was completely 
satisfactory. 

    6) One 'correlator reset' situation occurred.  (Data go bad, 
correlator resets on the next 10-second tick, good data resumes 10 
seconds later.  Unfortunately, the bad data are never flagged in this 
situation). 

    All in all -- OUTSTANDING performance.