[time-nuts] Training period for a Rb clock using GPS
parekh at berkeley.edu
Wed Jun 2 06:59:00 UTC 2010
Thanks that is really helpful.
On Tue, Jun 1, 2010 at 7:48 PM, Robert Benward <rbenward at verizon.net> wrote:
> The microprocessor "learns" the drift of the oscillator while it is
> connected, so that when GPS is lost, it can make those corrections in
> anticipation of drift. The longer it's locked to GPS, the better it learns
> the drift (more history). Don't confuse the word drift with "locked", even
> when locked, the oscillator is drifting and continuously being corrected.
> These corrections (the voltage to the EFC or electronic frequency
> correction) are an indication of the oscillator drift, even though the
> output is exactly 10MHz.
> Others can provide links to useful articles.
> ----- Original Message ----- From: "Abhay Parekh" <parekh at berkeley.edu>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at febo.com>
> Sent: Tuesday, June 01, 2010 10:36 PM
> Subject: [time-nuts] Training period for a Rb clock using GPS
>> I am a newbie at this, but have been playing around with 2 prs10s.
>> For our application we need to run the clocks without gps, but we do get
>> sync it to gps *initially* for as long as we want.
>> However, what we've noticed is that when we train it for short periods of
>> (< 1 hour a day) the clock drifts for a few microseconds a day once we've
>> gps, but when we train it for say 12 hours, its drift seems to be much
>> (sub sub microsecond/day).
>> We were wondering why this should be so! I apologize if this is obvious to
>> most of you but
>> I would greatly appreciate your help in shedding some light for us.
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