Difference between revisions of "2019 May"

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(May 10)
(May 10)
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'''15:14 UT''' I reset all of the gains just prior to the first calibrator scan, since I was not happy with the levels.  Based on an earlier snapshot of a geosat, it looks like Ant13 receiver is not working at all, but I will try it again in a half hour or so to see if setting the levels helps.
 
'''15:14 UT''' I reset all of the gains just prior to the first calibrator scan, since I was not happy with the levels.  Based on an earlier snapshot of a geosat, it looks like Ant13 receiver is not working at all, but I will try it again in a half hour or so to see if setting the levels helps.
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== May 14 ==
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'''22:00 UT''' Kjell was converting the new synthesizer for the correlator clock to its permanent location in the rack today, but ran into a lot of problems.  Eventually he got it installed and working, so I had to reboot the correlator as a result.
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== May 15 ==
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'''02:40 UT''' The delays were reset after the correlator reboot.
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'''12:02 UT''' It is getting frustrating that the Ant A control system dies each night around 2:00 UT.  I have been trying to do an overnight calibration (X-Y delay phase calibration) and for the past two nights it died each time.  The symptom is that the control system shows occasional 1-s outages most of the day, and then suddenly starts doing it a lot more (for a couple of hours) before it just stops.  To combat this, I am trying to restart it every four hours (at 1, 5, 9, 13, 17, and 21 h), so we will see if this helps.  Meanwhile, I could not even check the delays after the above reset because the Ant A receiver was not in the correct state for subsequent observations.  Hopefully the first calibrator scan of today will be good.

Revision as of 12:09, 15 May 2019

Back to Observing Log

May 09

11:03 UT The data from 19:00 UT yesterday until now are no good. Yesterday Kjell replaced the 800 MHz clock derived from the signal generator with one from a new Valon 5009 Synthesizer. Although the data seemed to be okay, I could not see any coherence in the phasecals or refcals. That prevented me from getting a delay correction. This morning I checked the delay using a communication satellite and discovered that two antennas, 8 and 14, had extremely high delays, about 300 ns! I rebooted the correlator this morning and rechecked, and now they are fine. I have seen this strange behavior once before, so I can only surmise that occasionally on a reboot of the correlator we can get really wacky delays on some digitizers (or ROACH channels--maybe not the digitizer itself). This suggests that we really need to make a quick observation of a satellite after a reboot in order to do a sanity check on the delays.

May 10

12:56 UT The delays have been updated this morning prior to today's calibrations. For some reason, ant13 has poor (but not zero) phase coherence as of mid-day yesterday. I just tried stowing to be sure it was not off in motor counts, but the stow looked nominal. I see no other indications of a problem.

15:14 UT I reset all of the gains just prior to the first calibrator scan, since I was not happy with the levels. Based on an earlier snapshot of a geosat, it looks like Ant13 receiver is not working at all, but I will try it again in a half hour or so to see if setting the levels helps.

May 14

22:00 UT Kjell was converting the new synthesizer for the correlator clock to its permanent location in the rack today, but ran into a lot of problems. Eventually he got it installed and working, so I had to reboot the correlator as a result.

May 15

02:40 UT The delays were reset after the correlator reboot.

12:02 UT It is getting frustrating that the Ant A control system dies each night around 2:00 UT. I have been trying to do an overnight calibration (X-Y delay phase calibration) and for the past two nights it died each time. The symptom is that the control system shows occasional 1-s outages most of the day, and then suddenly starts doing it a lot more (for a couple of hours) before it just stops. To combat this, I am trying to restart it every four hours (at 1, 5, 9, 13, 17, and 21 h), so we will see if this helps. Meanwhile, I could not even check the delays after the above reset because the Ant A receiver was not in the correct state for subsequent observations. Hopefully the first calibrator scan of today will be good.