TRG vs GPS Statistics of Jan-Apr 2001 run, part 1

Relative time between spills (via TRG 48-bit clock)

same as above, but zoomed in [2.17 ... 2.21] and with histogram

TRG oscillator drift from 50 MHz (*1)

Absolute spill time difference between GPS1 and GPS2 (*3)

Relative spill time difference between GPS1 and TRG (*2)

Relative spill time difference between GPS2 and TRG (*2)

Note: y axis is log scale

(1)*	Both, the TRG module and LTC module each use an internal, free-running 50 MHz crystal oscillator (independent) for their clock counters. The two oscillators are not temperature compensated! Therefore, any change of the room temperature in the North Hall control room causes them to drift. Cooler temperatures usually result in higher frquencies than at warmer temperatures.
(2)*	Absolute TRG clock vs. GPS time measurements cannot be made due to the mentioned temperature-dependent TRG oscillator drifts, as shown in the wave forms of the plots above. The waves are inverse proportional to temperature changes in the North Hall.
(3)*	On Feb. 07, 2001, GPS1 reported "Status or GPS Lock Error" from 13:42:23 until 19:12:35. See also zoomed plots for Feb.7/8, 2001. Probably, satellite synchronization lock was lost, cause unknown so far (antenna problem, firmware?). However, GPS1 appears to have stayed stable for more than 3 hours into the lock error problem. At approx. 16:55 it was first noticed that GPS1 slowly drifted away from the GPS2 time, up to 56.8 µsec difference at its peak at 19:02. Then it recovered and was back in synch again within 10 minutes.