Rule of thumb: quartz is best short term, Rb or H-maser mid-term, and Cs by far the best long-term.
For GPS clocks the long-term doesn't matter that much since each space clock is monitored and updated against the GPS master clock(s) on the ground. /tvb (iPhone4) On May 4, 2013, at 11:40 AM, Attila Kinali <[email protected]> wrote: > Hi, > > Bruce recently mentioned [1], where Fig. 2 shows that the Cs clocks > of the old II and IIA birds are less stable than the Rb clocks of the > newer birds. This struck me as odd and i tried to find out why > a Cs beam had worse stability than a Rb vabor cell. The only paper comparing > both clocks that i found was [2] which shows in Fig. 2 that the Cs clocks > are less stable even at very small taus. But the only mention of a property > that is worse for the Cs than for the Rb mentioned is that the Rb's are > temperature stabilized while the Cs is not. But i would expect the temperature > effect to be significant from a couple 100s upward, not down to 1s. > > > Can anyone shed some light on why the GPS Cs beams have a worse stability > than the Rb vapor clocks? > > > Attila Kinali > > > [1] "GPS clocks in space: Current performance and plans for the future", > by Dass, Freed, Petzinger, Rajan, 2002 > http://tycho.usno.navy.mil/ptti/ptti2002/paper18.pdf > > [2] "Atomic frequency standards for the GPS IIF satelites", > by Emmer, Watts, 1997 > http://www.pttimeeting.org/archivemeetings/1997papers/Vol%2029_19.pdf > > -- > The people on 4chan are like brilliant psychologists > who also happen to be insane and gross. > -- unknown > _______________________________________________ > 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.
