[time-nuts] DC Voltage Ramp?

[Brooke Clarke]

Hi Tom & Robert:

I think what this is saying is that if the control voltage to the OCXO 
is fixed, then during the 10,000 (or more) seconds needed for GPS the 
OCXO has drifted about 5E-11/day * 10,000/86400 = 6E-12 seconds which 
exceeds what we are trying to accomplish.

BUT, if instead of using a fixed control voltage, a Ramp is used then 
this will not happen.  Now instead of using GPS to control a fixed 
voltage it's used to control the slope of the ramp.

What am I missing?

Brooke

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Tom Van Baak wrote:

. . . >>With a one-way code receiver, the best stability you can get out 
of GPS is
>>about 10^(-8)/tau, corresponding to 10 ns jitter at 1 second.   As such,
>> it takes about 10^(4) seconds for it to integrate down to the 1e-12 level, by
>>which time your OCXO has wandered above it.  As such, it is tough to take
>>full advantage of a good OCXO by steering to GPS.