Hi guys, it may help to increase DAC gain to get faster recovery times from "bumps" etc. On an OCXO, the frequency recovery from an upset should happen within a couple of minutes, definitely less than 15 minutes to achieve frequency lock. The phase recovery (to 0ns offset) may take a couple of hours to do. If it takes a very long time to recover, then I think increasing the DAC gain, or alternatively the EFCS and PHASECO together may help. Wikipedia has some good instructions on how to optimize PID type controller gains to get the fastest response with minimal noise... Also, please make sure to disable temperature compensation when using the external source, unless a thermistor is connected to the board, sensing the Rb temperature. Otherwise the temperature compensation may add noise due to it scaling the gain to huge values due to the missing thermistor. bye, Said In a message dated 7/27/2010 09:58:41 Pacific Daylight Time, [email protected] writes:
My experience is very similar to Scott's. I ran many hours with both an LPRO-101 and FE-5680A. The disciplining behavior and Fury settings were the same for either Rb. My biggest disappointment was the recovery time due to various common or intentional bumps or especially, after power loss. I also had to let the "system" settle in for a week before acceptable tracking smoothed out. Any long term slope to the EFC trace (gpscon) caused excessive hunting and this didn't settle down until the Rb was VERY stable. My gpscon TI and stddev was virtually the same as Scott's if I had EFCS set to 1.0 to 1.5 but recovery was unacceptable (maybe 24-hours) so I usually ran at 2.0 or 3.0 with slight degrading of stddev to around 3.2. This EFCS setting allowed a much better settling time around 3-hours. DACG= 1000 EFCS = 2 to 3 EFCD = 50 (25 allows little better settling time) PHASECO = 15 (I favor 10 Mhz over PPS) Regards... Don _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
