Hello, Time-Nutters-- I have a couple of friends who have asked how GPS based time & frequency units arrive at their level of precision. One sent me some questions and comments (see below) which indicate his lack of understanding of how GPS disciplined oscillators can deliver the precision they do.
My question is-- Can anyone on the Time-Nuts list point me to a source I can give them that will explain how the process works? Seems to me that I have seen some papers describing the process but my search for this info has not turned up anything suitable that goes into some detail on this. Any feedback or suggestions on this is much appreciated!! Mike Baker Micanopy, FL **************** Here is what one of the guys sent me: A 2GHz Intel processor can't measure 10^-12, let alone getting a P4 to do it. RS232 delay times are measured in mSec, not 10^-9. Yes it can time-stamp PPS at 10^-9 if it had a time source that accurate but that has nothing to do with when the pulse gets to the receiver or the original time source of the system. Given that my phone has a 2+ GHz processor / clock and a GPS receiver, what is the advantage of a 6 GHz (or 10 MHz) oscillator? I could well believe that system is accurate to 100 nSec (10^-7) or that a Stratum 0 GPS system good down close to 10^-8 (40 nSec). I don't see any way of getting down to 10^-12 with that technology or transmitting a time more accurate than 10^-7. If the original GPS time source is 10^-7 or a little better, how can it ever be more accurate than that? What are we missing? ****************************** _______________________________________________ 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.
