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07/22/2006 Entry: "Timing Updates"

After almost 90 days of data collection from the three standards versus GPS and each other, I reset things today, mainly because RB1 had drifted behind GPS and that caused the counter triggering to be goofed up. I also tweaked CS1 very slightly.

After setting the C field to 4.98, CS1 had been running about -7x10^-13. I nudged that up a tiny bit to 5.05 (which was a bit high before, but seems like it should be about right based on current data).

In order to provide more adjustment range, I changed GPSDO2 (one of the Z3801As) to run 500us early (it had been 10us early); that combined with the 5359 time synthesizer will give me plenty of range to set the various clocks to the proper relative delays.

I've reset RB1 to be the full 500us early. CS1 is set to be 10.2us early, and CS2 is about 19.2us early. That should leave plenty of room for drift before stop precedes start.

I'm now resuming data collection with these adjustments.

Oh, and a note for future reference -- I wasted a lot of time trying to figure out what was wrong with the 5359A time synthesizer when it didn't seem to recognize an external trigger -- or at least, the output wasn't triggering the 5370B counter. Turns out I had the output pulse width set too short. Setting it to 1us or longer solved the problem.