Good point. How was the position of the so called "Totally Accurate Clock" obtained. Strange name though - no such thing as a totally accurate clock...
:-) Rob -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: 05 August 2008 10:55 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt v Active Hydrogen Maser 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. > _______________________________________________ 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.
