[time-nuts] Adafruit Ultimate GPS timing message arrival times

Mark Sims holrum at hotmail.com
Sat Jul 30 17:20:49 EDT 2016


It is only tracking the GPS sats,  running at 1Hz rate.   Almost every GPS receiver that can run faster than 1Hz has warnings that the 1PPS output is only valid/stable if the device is configured for 1Hz output.



My Ublox 8 receiver tracks GPS/Glonass/Beidou/SBAS sats.   I have seen it tracking over 24 sats, but its NMEA and binary messages timings are very stable.  Remarkable considering all the NMEA sentences it take to report all those sats.



I'm currently collecting histogram data from the Trimble Resolution-T SMT (TEP) receiver... it has one of the worse standard deviations of all the receivers that I tested (the TEP version can run in either TSIP and Motorola emulation modes, both had poor message timings).   The original Resolution-T had very stable message timing performance.


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> Isn't this the receiver that hears a very large number of GNSS satellites and also has a 10 Hz update rate? If so, I'd expect that there would a large variation in message lengths. How stable is the 10 PPS or 1 PPS output?


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