The periodic +/- might be caused by periodic error in the PPS. The UT+ has an error "sawtooth" function. That is the error is the PPS is left to accumulate and then it is reset. So if you DAC counts goes up and down on a few seconds or few tens of seconds period it could be tracking the error in the PPS. The UT+ keeps its PPS within spec. Once you gt the serial line connected you will be able to read the sawtooth corrections. The UT+ out puts the estimated error in the PPS and I guess a very sophisticated GPSDO would use that data to correct the phase measurement. From memory, I think with a UT+ the error in the PPS goes up to about 50 ns. (I have a couple UT+)
-- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
