So why did the Totally Accurate Clock show the same pattern? On 05/08/2008, Rob Kimberley <[EMAIL PROTECTED]> wrote: > 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. >
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