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Clock System Log

 as of Saturday, 09-Apr-2016 20:11:37 AST

Go to Most Recent Entry

NameEmailDateComment
Dana Whitlowdwhitlow@naic.eduThursday, November 21, 2013 16:40:02This is a test entry to check out the new logs in the logging system.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:11:30Feb 14 2011: Decreased H-maser frequency by 2.0e-14
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:13:246/28/2011 & 6/29/2011: Replaced both vacion pumps in H-maser.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:16:08Aug 17 2011: Decreased H-maser frequency by 2.7e-14. The need for this was probably due to side effects of the vacion pump replacements in late June of this year.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:20:08Sept 7, 2011: Lost AC power to both TRAK clocks in clock room due to a UPS malfunction. This resulted in total loss of station time. TRAK-1 (the station master clock) was reset as best as could be done considering its coarse (1 usec) setting granularity, leaving it approx 450 nsec ahead of UTC(NIST).
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:22:20Sept 13, 2011: Reset TRAK-2 as accurately as its 100nsec granulatity would permit, leaving it approx 30 nsec ahead of UTC(NIST)
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:26:40Mar 2, 2012: TimeTrace RX quit logging data. Initially attributed to GPS antenna/feedline problem, but later recognized as one symptom of a general "crash" syndrome in which the RX needs restarting (and sometimes even a power cycle operation) to get it going again.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:28:284/23/2012: GPS-1 had quit logging. Problem eventually solved by replacing old BNC cables running between the two chassis of the receiver.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:30:01May 8, 2012: Increased H-maser frequency by 3.0e-14 at request of Bill Diener.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:31:39June 8, 2012: Increased H-maser frequency by 2.0e-14 at the request of Bill Diener.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:34:43July 1, 2012: Last night was a leap second event. Used auto-leapyear function on TRAK-1, update occurred at midnight AST (4 hours late for UTC). Updated TRAK-2 & TrueTime clocks today, and did the necessary cold start of GPS-4.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:36:33Oct 25, 2012: Increased H-maser frequency by 2.8e-14 at request of Bill Diener.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:39:38Nov 1 thru Nov 5, 2012: Tried replacing USB-serial interface dongle on TimtTrace system, which failed to solve the (now) longstanding problem with logging stoppages. More stoppages, culminating with loss of GPS sat lock, which required power-cycling the RX to restore operation.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:40:49Jan 9, 2013: GPS-1 lost 10MHz phase lock, restored operation by retuning VCO.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 09:46:10Mar 18, 2013: First observed abrupt (but not severe) rise in IF amplitude in H-maser. This turned out to be the precursor of a long-term problem (still ongoing as of Nov 22, 2013) in which the IF amplitude and Pd heater voltage are oscillating with a period of 10-11 days. The cause is unknown and there is no apparent trouble otherwise. The Owings brothers at Symmetricom have since told me that one other owner had a similar problem, which persisted for months and then mysteriously fixed itself. So I continue to watch and wait.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 10:35:38Late May, 2013: GPS-4 failed while I was away on vacation. I talked Mike Nolan into springing for a Rb standard from SRS, which we bought and is currently being disciplined by the output of the new CNS II GPS receiver which we bought about Mar 22, 2013. (I forgot to mention that, didn't I?) The 1PPS output of said new GPS receiver has also been connected to the "GPS3" port of the CCS MUX. Having this new capability, we decided to decommission the failed GPS-4, which has gotten to be too much trouble to keep up.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 10:50:17June 7, 8, 9: Connected the original (old) GPS-3 RX's 1PPS output to the "GPS-4" port on the CCS2 MUX, and connected the GPS-4 antenna to the old GPS-3 receiver, in the interest of keeping the old GPS-3 RX warm and fuzzy. Renamed the CCS2 channels involved "NEW GPS-3" and "OLD GPS-3" and continue to record them both with CCS2.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 10:56:25Oct 31, 2012 through Nov 4, 2013: Replaced the H-maser's backup batteries, but became suspicious of their condition when the charge current failed to drop off to low values in a timely manner. Put the old batteries back in, then have been charging the new batteries off-line ever since. Only about now (Nov 22, 2013) have the charge currents fallen to the 10 mA (or less) regime. Bryan Owings of Symmetricom suggests running a discharge test on the new batteries at approx 4 amps to see how long they will run the test load. I will do this if/when I can find some suitable power resistors and commit the time to babysitting the setup for the duration.
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 11:04:52Nov 15, 2013 thru Nov 21, 2013: Started trial operation of the new TMAS system from NIST, which came at an opportune time because the GPS-1 RX failed just a few days earlier. It seems to be working, but the time differences differ from GPS-1's values by more than 100 nsec. Mike Lombardi of NIST pointed out that the antenna height entered into the GPS-1 was something like 50m higher than the value I entered into TMAS. The TMAS value I entered came from the geodetic GPS survey we had done for the TimeTrace antenna several years ago. So we need to determine just why the big discrepancy in the antenna height figures. It will probably take a new survey to find out for sure. It's terrible "having two clocks"- I don't even know what time it is!
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 11:14:52Oct 31, 2013: Increased the H-maser frequency by 4.0e-14, at request of Bill Diener
Dana Whitlowdwhitlow@naic.eduFriday, November 22, 2013 11:19:27Nov 17 thru Nov 19, 2013: Found that TimeTrace RX was no longer receiving satellites. Initially suspected antenna problems due to nearby work installing TMAS antenna. But the failure turned out instead to be a somewhat atypical crash of the TimeTrace RX, fixed only by power cycling the unit. As of Nov 22, still working.


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