Hi, Where can I purchase one or two of the time-nuts Tbolt specials?
Thanks, Pieter ----- Original Message ----- From: "John Ackermann N8UR" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, August 09, 2008 4:27 PM Subject: [time-nuts] TBolt and Z3801A performance data >I just put the results of some tests of 2 "Time-Nuts Special" > Thunderbolts, as well as 2 Z3801As, at > http://www.febo.com/pages/gpsdo_comparison/ > > I learned an interesting (and important) lesson in doing these > measurement. I initially measured the pairs of GPSDO against each other > (e.g., one TBolt as "reference" and the other TBolt as "DUT"). In > theory, if the two oscillators are identical, and if their noise is > uncorrelated, the results of the pair can be used to deduce the results > of the individual units. > > However, in this case doing so gave a very optimistic view -- the TBolts > were better than the pair of Z3801As! Another set of measurements > comparing the GPSDOs against an independent reference revealed that the > first measurement was a lie. > > I guess you can think of it like this. Picture two OCXOs that both age > at the same rate and in the same direction. Because they drift > together, measuring their relative phase hides their actual drift and > makes them look better than they are. On the other hand, if they were > drifting in opposite directions, they would look worse than they are. > An identical aging trend is a "correlation" even though it's external to > the things we usually think of. > > John > > _______________________________________________ > 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.
