[time-nuts] GSP clock stabilitiy, Rb vs Cs

Attila Kinali attila at kinali.ch
Sat May 4 14:40:34 EDT 2013


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

[2] "Atomic frequency standards for the GPS IIF satelites", 
by Emmer, Watts, 1997

The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
		-- unknown

More information about the time-nuts mailing list