[evlatests] the L302 amplitude glitch

[Ken Sowinski]

On Wed, 31 May 2006, Ken Sowinski wrote:
>
> After examining the data on disk, I can confirm that I saw no
> no glitches and that Walter did.  Differences?
> 1.  Different executor.
> 2.  I had the source marked as a calibrator, but Walter did not.
> 3.  Modcomps were rebooted inbetween the observations.
> 4.  Different HA.
> It is hard to see that any of these are relevant.

There are two more variables:
1.  I used Xsysstart; Walter his own file.
2.  The scripts were started at different instants.

One of these might be able to explain what I am about
to describe.

We used some dynamic time this afternoon to examine the
glitches more carefully.  Three different observations
were attempted.
1.  I ran the EVLA antennas using Xsysstart and an up to
     date local copy of the executor.
2.  We ran a file devised by Walter which does only X band
     and was run by the operator.
3.  We will try to run the same file as last week, which
     cycled over all the bands several times.

I write this as 2. is in progress.

1.  When I ran Xsysstart I saw no glitches on any IF
examining antenna 4 x 13.

2.  I had the operator start Walter's simple X band file
at about 0520 LST.  It worked file until 0530 LST which
was its sceduled start time and then the usual glitches
appeared.  I asked the operator to kill the script and
the glitches ceased.  I then ran the same script using
my executor and the glitches were present.  Again the glitches
ceased when I killed the excutor I was running.

At 2001 IAT I asked the operator to run the Xsysstart script,
and no glitches were seen.  This script was killed at about
2003 IAT.  Then Walter's sript was started again and no
glitches were seen.  Over time however the amplitude slowly
devreased and phases started winding; it looked like the
executor was not really running, or not sending commands
to the antennas.

3.  Walter's seoond file was started at 0600 LST and I
see glitches at X band.  I leave it to others to examine
this dataset more careully to see what mysteries might
lie there.


Tentative conclusions
1.  There is a difference between Xsysstart and other
scripts, or,
2.  Whether glitches occur or not depends on exactly when
the script is started.