[evlatests] Another test of 'OTF/ACU

[Rick Perley]

     I ran a 20 cm test yesterday, the purpose of which was to check on 
the reliability of the phase/delay tracking.  (Result:  as expected 1 
second is not reliable, 2 and 4 seconds is).

     This test cut back and forth across the L-band beam, using beefy 
3C147.  All travels were short (2nd null to 2nd  null), and only in the 
RA direction.  The source was at high hour angle, to the motion would 
have been more in elevation than azimuth.

     I did a 'quick and dirty analysis', comparing the transit times of 
ea14 to ea13, and ea21 to ea20 (using the same polarization).  As in the 
x-band best, referenced pointing was done and applied.

     The results here are with '6X' sidereal rates -- it takes about 9 
seconds to traverse the beam (3dB) at 1450 MHz.  'Delay' means the 
delay/setting time.  Results are below:

     Motion   Delay  IF/Pol     14-13      21-20
--------------------------------------------------
     W to E      1s      1R         0.4 s        0.63
                               2R         0.35         0.55
                               1L          0.36        0.64
                               2L          0.30        0.61

     E to W      1s      1R         0.15        0.02
                               2R          0.23       0.10
                               1L          0.18        0.04
                               2L          0.26        0.05

     W to E      2s      1R         0.19        0.46
                               2R         0.11        0.40
                               1L          0.20        0.45
                               2L          0.06        0.43

     E to W      2s      1R         0.17         0.05
                               2R         0.28         0.09
                               1L          0.21         0.04
                               2L          0.34         0.03

     W to E      4s     1R          0.31        0.50
                              2R          0.26        0.42
                              1L           0.31        0.47
                              2L           0.20        0.46

     E to W      4s      1R         0.06         0.10
                               2R         0.15         0.15
                               1L          0.08         0.10
                               2L          0.18         0.10
--------------------------------------------------------------

Two observations:

     1) All differences are positive.
     2) The E to W motion always has a smaller offset than E to W. This 
could be due to a pointing error, but that shouldn't be the case here 
since referenced pointing was done (but I don't know if this was 
successful, since I received no solutions).