[time-nuts] Thunderbolt versus Home made
not.again at btinternet.com
Sat Feb 17 06:58:08 EST 2007
On Fri, 16 Feb 2007 17:44:14 -0600, you wrote:
>Richard W. Solomon wrote:
>> I looked at the ACE-III on Trimble and do not see mention of a 10 KHz output.
>> Maybe I miised it, but without it, the N1JEZ board will not do unless you modify
>> it for 1 pps.
>> I am trying to find more info, but since it reached EOL, Trimble may have deleted
>> 73, Dick, W1KSZ
>You are correct, you need to patch another set of dividers in the chain.
>Keep in mind that the only benefit of a 10 kHz output on the Jupiter is
>to save 4 decade dividers. You should not use the fact that the Jupiter
>outputs 10 kHz to speed up the loop in a GPSDO. The loop bandwidth is a
>function of the crossover point between the VCXO and the GPS, which in
>most cases will be between many minutes (cheap VCXO) and a few hours (HP
>10811). Whether you use 1 Hz or 10 kHz comparison frequency into the
>phase detector will not affect the filter.
(As this is my first post here, I'll try not to mess up too badly :)
I think that for a simple controller like the N1JEZ board, a 10KHz
output on the GPS really is needed.
I tried a circuit like that with 100pps once out of curiosity, but as
I remember, the lower error sensitivity made things more difficult.
BTW, with a standard GPSDO, would using the 100Hz/10KHz the pulse not
reduce the need for a fast comparator clock, and also reduce sawtooth
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