[time-nuts] Thought experiment on a low cost timing board

Tim Shoppa shoppa at trailing-edge.com
Thu Feb 23 17:13:25 EST 2006

John Pettitt <jpp at cloudview.com> wrote:
> More importantly can somebody opine
> on if it's possible to use a 1PPS to discipline an OCXO 

Certainly yes. Google for "Z3801A" (telco surplus units)
or for "Brooke Shera" with "GPS" (more of a roll-your-own, with
low-tech SSI/MSI-type logic and a PIC in one particular implementation).

The same ideas have been cooked up in different ways many times
over in other products/projects.

> (I've seen
> designs to it from a 10KHz signal for sale on eBay)) -

The 10kHz reference is nice for quick locking, but typically OCXO's
don't need any stabilization over the ms time scale.
The 1PPS+OCXO units typically take many hours to a few days to settle
down, and then they can promise holdovers of a few microseconds for the
first day of unlock (which is what the surplus telco units were built
to hold up for).

If you like coming up cold and locking quick (probably faster than
the oven stabilizes), then sure 10kHz is a great idea.


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