[evlatests] A more complete description

[Rick Perley]

    I've now reviewed all the data taken in the test  yesterday 
afternoon to check on system performance. 

    To repeat:  There are four different correlator modes utilized, 
observed cyclically, two of these are OSRO1 modes, two are OSRO2 modes.  
Each observation at each mode is observed 3 times, for one minute each.  
The cycle ran three times around -- 36 minutes total. 

    The 'hop report' is now slightly augmented from the earlier report:

    Multiple phase jumps, always at scan boundaries, and always the same 
on opposite polarizations, were seen on:

    2AC
    20AC
    25AC
    3BD
    28BD

    Other notable effects are:

    1) There are excessive numbers of 'integer zero records':
          OSRO1, BW=4 MHz:  12%
          OSRO2, BW = 31 KHz:  26%
          OSRO2, BW = 16 MHz:  22%
          OSRO1, BW = 64 MHz:  10%
             Inspection shows that the extra large fraction of zeros in 
OSRO2 modes are nearly all associated with antenna 14, 15, and 16 on the 
'C' IF, for which all data were zeroed.  But other antennas/baselines 
are also 'blank' at times. 
             Most of the ~10% blanks in OSRO1 mode are found within a 
few 10s of seconds of the data following a *mode change* (not scan 
changes with the same mode). 

    2) Antenna 17, in RCP, is very weak --- amplitudes are low by a 
factor of a few.  This is a real SNR loss, not a simple scale problem.  
I suspect the receiver. 

    3) Antenna 26, IF 'C' only, gives no fringes in OSRO1 mode only.  It 
fringes fine in OSRO2.  Sounds like a correlator issue to me ...