[evlatests] Phase/Delay jumps on ea13 and ea26 at X-band

[Vivek Dhawan]

I bet this is delay clunks, seen through whatever processing
was done by Rick. If I'm wrong, I'll treat him to a bottle of
WalMart's (socorro) finest wine. and conversely...

On Thu, April 12, 2018 09:50, Rick Perley wrote:
|  Â Â Â  I'm reducing science data taken on the strong quasar 3C273. The
| program cycles through X, Ku, K, and Ka bands.
|
|  Â Â Â  Overall, data quality is excellent.
|
|  Â Â Â  However, I've noted a peculiar effect for antennas 13 and 26, at
| X-band (using 8-bit sampling).  There are two distinct delay/phase
| states, differing by 40 ps in delay, and 140 degrees in phase.  (Likely,
| the former causes the latter).
|
|  Â Â Â  In most cases, when the antenna is tuned to X-band, the resulting
| delay can be 40 ps different than the last observation at that
| frequency.  However, in many cases, the delay/phase jumps *in the middle
| of the scan* to the alternate state.
|
|  Â Â Â  The jump scale is the same for both antennas, and is identical in
| both polarizations.  The jump times, however, are completely
| uncorrelated between the two antennas.
|
|  Â Â Â  These jumps are definitely *not* due to atmospheric effects --
| which are easily seen on all antennas, are of a completely different
| characteristic.
|
|  Â Â Â  I have yet to review the data from the other bands (or the 3-bit
| data from X-band) -- and will report the results when I do this.
|
|
| _______________________________________________
| evlatests mailing list
| evlatests at listmgr.nrao.edu
| https://listmgr.nrao.edu/mailman/listinfo/evlatests
|