Hi Time data reported in the same manner supports the same "2 to 4 ns" over similar time periods.
Bob On Aug 24, 2010, at 3:46 PM, [email protected] wrote: > Dear tbolt-nuts, > > A friend and I have played a little with zero baseline tests and > Thunderbolts. > > Have some very early results, on measurements from two identical TAPR > Tbolts. These were connected to the same antenna. Its a good antenna, with > a rather open skyview. One receiver was hooked on a 4-port passive GPS > splitter that is connected to the antenna with some 15m of LMR400. The > other tbolt got signals from a downstream 8-port HP L1-splitter. > > Both receivers had identical configuration. Non-default settings with > tboltmon was, > > message 0x5A enabled (incl. pseudorange and doppler) > doppler smoothed pseudorange (not relevant for todays discussion) > synchronized measurements (what does this do exactly?) > > Both receivers have done site surveys. Surveyed positions not identical. > Position diff TBD. > > Raw serial data was collected with two sessions of 'TsipNmeaDemo', each of > the Tbolts connected with USB-serial cables. Some 20 minutes of continous > data was collected from the receivers. Message 0x5a was decoded. > > In the first plot shows (tbolt1.dopper - tbolt2.doppler) for all 8 tracked > satellites. Results are scaled from Hz at L1 to m/s. A few satellits have > a std dev around 1cm/s, most around 5mm/s. This equals 8 measurements a > second with a noise of 1/30ns or better. > > http://www.lysator.liu.se/~bg/timenuts/sd_doppler.png > > Second plot shows a simple integration (summation) of the above > velocities. The worst satellite moves around 90cm (ca 3ns) in 20 minutes. > > http://www.lysator.liu.se/~bg/timenuts/csum_sd_doppler.png > > Any comments? questions? > > Has anyone else played with 0x5a on their Thunderbolts? > > -- > > Björn > > > > _______________________________________________ > 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. > _______________________________________________ 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.
