I'm pretty certain that this due to position error. You state that you have a 5m error in position. 5m equates to approximately 15nS.
Having seen similar results before from positional errors it would be good idea to let the unit self survey and then run the tests again. Rob Kimberley -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Palfreyman Sent: 04 August 2008 10:47 To: [email protected] Subject: [time-nuts] Thunderbolt v Active Hydrogen Maser Hi folks, I took my recently acquired Thunderbolt, along with my 5370B, to the observatory on the weekend and plotted its residual against the NR Active Hydrogen Maser. See the attached graph (ignore the "line of best fit" heading - 0.00 was simply the starting point). Note that I didn't let the Thunderbolt do a survey, I simply plugged in the local GPS coordinates which I later verified were about 5m to the east of the actual Thunderbolt antenna. The y axis is residual in nanoseconds and the x axis is Modified Julian Date. I find the residuals fascinating. Note the identical repeating residuals in a 24 hour cycle. Is this due to thermal or constellation issues? The local GPS (not a GPSDO but an early version Totally Accurate Clock) showed a roughly (very roughly) similar pattern when averaged with 5 minute averages to hide the awful 100nsec sawtooth. The observatory is air conditioned (but with poor insulation) and has many devices constantly running. I doubt it is thermal, however the low point is at 6:30am in the morning, just before I arrived. Can anyone provide comment on this pattern? Regards, Jim _______________________________________________ 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.
