Bruce Griffiths skrev: > Magnus Danielson wrote: >> Tom, >> >> Tom Van Baak skrev: >> >>> Ah, OK. So you keep the antenna connected and you keep the >>> GPS receiver in position hold mode, still receiving fixes. >>> >>> All you're doing is disabling the software disciplining algorithm. >>> That sounds like a good test. Let me try this too and see if I >>> agree with your conclusions. >>> >> We discussed this a little while back. I proposed a three-cornered hat >> using two receivers and one counter... as the Thunderbolts has a builtin >> TIC to GPS which can be logged. We also discussed just running a single >> Thunderbolt in holdover. Others had already tried that approach. Bruce >> and I discussed to some degree the effect of steering on the result. >> >> >>> I'll try to simultaneously measure the 1PPS or 10 MHz outputs >>> as you suggest. >>> >>> Has anyone hacked a TBolt yet to find which internal pin has >>> a raw 1PPS from the GPS engine (as opposed to the 1PPS >>> divided down from the OCXO)? >>> >> Hmm... I have not even "repaired" (in the sense, that they are broken >> until opened and "repaired", i.e. just looking under the hood for sake >> of curiosity). any of mine... >> >> Cheers, >> Magnus >> >> _______________________________________________ >> 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. >> >> > Magnus > > There may not even be a real PPS signal produced by the GPS engine which > is compared with the PPS generated by dividing down the OCXO output. > With the GPS engine LO derived from the OCXO, having a real PPS signal > generated by the GPS engine for such a comparison isnt necessary in > order to measure the phase error of the PPS signal generated from the > OCXO output.
Actually, the PPS out may very well be the PPS output of the engine... But yes, I agree. There is no point in realizing the PPS twice when you dicipline the OCXO anyways, and the time-difference is never measured by a TIC, the GPS solution gives the time-error and the PPS only need re-assignment when it is too big. Cheers, Magnus _______________________________________________ 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.
