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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.