> The other thing I've wondered about is how did HP correct the but in the > early > sawtooth error back when SA was on?
Brooke, Someone with a 'scope probe could tell for sure but my understanding is that they didn't correct for sawtooth in hardware or in software. One reason may be that early PVT6 or VP's didn't have a reliable sawtooth correction message. Dr TAC could comment on this. The other reason is that, as many of us have pointed out, sawtooth correction is nice but not necessary for a GPSDO. The longer the time constant the more true this is. So the HP SmartClocks had two things in their favor in this respect. One is a very high-performance OCXO allowing a longer time constant than other GPSDO. The other is that they were designed when S/A was in effect. Everyone designing GPSDO's in the 1990's needed to have longer time constants -- to reduce the effects of S/A. Consequently, sawtooth was less of an issue than it is now. So those are my three hunches. Anyone know for sure? /tvb _______________________________________________ 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.
