[time-nuts] frequency reference for portable operation
magnus at rubidium.dyndns.org
Mon Mar 11 07:03:26 EDT 2013
On 10/03/13 16:17, Bob Camp wrote:
> Remember - OCXO's are going to be acceleration sensitive. As you bump about on back roads, the oscillator is likely moving around by a few ppb. If you are after a hertz at 10 GHz, that's a lot.
> Your GPS will be off by a fairly predictable amount based on it's idea of it's location. If you have a 3M position accuracy, then you will likely have 10 ns of time error. With a 10 second loop, you are right back to a ppb.
> A good Rb should be able to hit a sub ppb accuracy at 10 minutes.
If you keep the OCXO on the Rb heated, you should get quicker on the
mark. Then it is mostly the heatup of the physical package which
consumes power and time then.
Then again, pre-heating with the car cuts down warm-up times.
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