[evlatests] A curiosity with antenna 12

[Joseph P. McMullin]

Jim, Hichem,

Is it possible to poll the versions of the M301 firmware on the other
antennas and confirm that
they are consistent (rather than empirically determining this).
Similarly, given Hichem's last note, can we review the M301 MIBs for
surprises.

Joe

On Wed, Jun 30, 2010 at 5:18 PM, Jim Jackson <jjackson at nrao.edu> wrote:

> Antenna 12's M301 had the wrong version of firmware in it.  It was
> the version we installed in early April that was pulsing the switches
> every time a command was received. I don't know why this module
> didn't update when the rest of them were done on 21 April - possibly
> the antenna was being worked on and wasn't communicating.  It has now
> been fixed and has the same firmware as the rest of the M301's.
>
> Jim
>
> At 04:48 PM 6/29/2010, Ken Sowinski wrote:
> >On Fri, 25 Jun 2010, Rick Perley wrote:
> >
> > >    Michael took a short (27 minute) observation in 2 GHz-wide mode a
> > > couple days ago.   Eight full-polarization subbands, each of 128 MHz
> > > width, in each of the AC and BD IFs.  In general, beautiful data.
> > >
> > >    It was noted that antenna 12 had a curiousity -- once every minute,
> > > on all subbands, in all polarizations, the amplitude dropped by about
> > > 10% for a single 1-second record.  This was the only antenna for which
> > > such a effect was noted.  As the script asked for a new scan every
> > > minute, I had assumed the 'drop-down' was a first-record, or perhaps
> > > second-record problem.  It's not!
> > >
> > >    This 'drop-down' is a 2nd-record effect -- the 2nd record of every
> > > scan is low by this much.
> >
> >this is still happening.  It is really synchronous with the
> >the new scan and is happening at the antenna.  The evidence
> >is that all the T304 power meters show a one or two dB dip
> >at each scan.  Since it is seen in the input power meter it
> >must be happening upstream of the downconverters.
> >
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-- 
Dr. Joseph P. McMullin
EVLA
Ph: +1 575 835 5700
E-mail: jmcmulli at nrao.edu
http://science.nrao.edu/evla/
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