[evlatests] Another test of 'OTF/ACU

[Ken Sowinski]

We ran this again a few minutes ago and Greg found a problem in
the 'command pre-processing' of the new ACU.  That may well explain
the differences seen in the two directions when comparing old ACUs
with new in the table below.

Rick, can you make the same comparison for a couple of cases of antennas
with only the old ACU?

Ken


On Wed, 4 Mar 2015, Rick Perley wrote:

>    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).
>
>
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