[time-nuts] Timing Distribution in Mountainous Terrain

Bob Camp lists at rtty.us
Fri Sep 10 01:27:00 UTC 2010


Hi

If 30 ns is the system goal, then you have a lot more to budget for than simple clock error. You could easily be below 10 ns for just the clock portion of the budget. I suspect that multiple 5071's and a maser or two at each site will be the ultimate solution if each must stand alone for 6 days and the set of 10 stay within 30 ns p-p. If reliability planning includes 6 days past end of GPS it also likely includes significant redundancy and more than a few 9's in the confidence factor.

I suspect it's cheaper to buy the 5071's than to have a half dozen SR-71 category aircraft ready to climb high enough to act as common view targets. High altitude balloons might work pretty well and they would be cheaper to keep in hot standby mode.

Bob



On Sep 9, 2010, at 8:01 PM, "Rick Karlquist" <richard at karlquist.com> wrote:

> Adrian wrote:
>> Ralph,
>> 
>> so you're talking about 5.8E-14, right?
>> I'd think no off the shelf caesium, even when run in a temperature
>> controlled environment, will get you there.
>> Well, at a first glance, a 5071A with high performance tube would, if
>> you keep any environmental effects out.
>> So you'll likely need to sync them through a reliable and reproduceable
>> link.
>> Just a quick shot though.
>> 
>> Adrian
> 
> I would like to point out that the environmental sensitivities of
> the 5071A are unmeasureable, and the measurement threshold is
> far below 5.8E-14.  I would estimate that the 5071A (and ONLY the 5071A
> among commercial clocks) could get the job done provided that you could
> compare its frequency to GPS to the stated accuracy.  This would
> be using the 5071 as a secondary standard.  You still need to
> deal with the short term stability of the 5071A, depending on
> your system needs.  JPL uses H masers as flywheels.
> 
> Rick Karlquist N6RK
> member 5071A design team
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 




More information about the Time-nuts_lists.febo.com mailing list