Hi It sounds like you are not doing sawtooth correction. If that is correct, then you may have been watching hanging bridges.
Bob > On Jan 16, 2015, at 7:03 PM, d...@irtelemetrics.com wrote: > > Hi All, > > I've been playing a Ublox 6T receivers on a synergy SSR-6Tru module. The unit > has been running as part of a GPSDO. In logging the phase between GPS PPS and > OXCO, a few days ago the normally small amplitude short term (10s to ~500s) > phase wander became rather erratic. For the previous several months the short > term wander was around +/- 3nS to 5nS. All of a sudden this jumped up to > about +/- 25nS. > Anyway, the guess was that it was GPS related. So the first step was to > verify GPS was still using the last survey-in points, which it was. The > modules was seeing 14 or 15 good birds at a signal strength of 35 to 50. For > kicks another survey in (48 hour) was started, which just finished up today. > As soon as the survey in completed the phase wander dropped back down to > about +/-3nS. The change was immediate, like a switch was thrown. The > antenna hasn't moved, but the corresponding survey coordinates from September > and January show a phase center position change of about 1.8m. This seems > like a pretty small number, and wouldn't have expected it to make that big of > a difference. At this point I'm not sure what to think. > > Has anyone seen any of the Ulbox 6T modules PPS suddenly get 'noisy'. Is > there anything else I should be looking at? > > Any recommendations on what I should be setting for NAV5 and NAVX5 settings > that could improve things? Elevation angles, or C/N thresholds? > > I'm quite puzzled by this sudden degradation of the system. > > Thanks, > Dan > > > _______________________________________________ > 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. _______________________________________________ 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.
