[time-nuts] Orbiting crystals

iovane at inwind.it iovane at inwind.it
Fri Jun 26 19:25:57 EDT 2009


Time-nuts,

this post wouldn't be merely speculative, I have an actual 
interest in knowing if what I'm going to ask is possible.
As it has already been discussed here, crystals may jump in 
frequency. If I recall, about 20% of good quality crystals are
prone to jumping, but a crystal that used to jump might not 
jump anymore, a crystal that never jumped might jump in the 
future, and so on.
The trace of a disciplined (atomic or GPS) jumping crystal 
shows spikes (because it is soon steered), while the trace of 
its control voltage shows permanent changes in level. 
Well, I thought it is legitimate to assume that orbiting 
crystals, namely the ones disciplined by caesium aboard GPS 
satellites, are not extraneous to the issue.
And here is the question: may a time-nuts grade equipment 
detect this?
The answer would not be simple. In the majority of cases we 
get from our multichannel GPSDO the 1 PPS pulse. How may the 
pulse be affected by the spike in frequency of a single 
orbiting crystal?
I know this list is also populated by qualified professionals,
and hope to get for sure one of the following conclusions:
-crystals aboard GPS satellites do not jump at all;
-if they do, time-nuts can't detect this;
-time-nuts can detect jumps, but can't identify the jumping 
satellite;
-time-nuts can detect jumps, and can identify the jumping 
satellite;

Thanks.
Antonio I8IOV





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