[time-nuts] frequency reference for portable operation

[Bob Camp]

Hi

With most modern lightweight Rb's the OCXO is integrated into the same heater block as the physics package. That makes it a bit tough to heat one without heating the other. …

Bob

On Mar 11, 2013, at 7:03 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> On 10/03/13 16:17, Bob Camp wrote:
>> Hi
>> 
>> 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.
> 
> Cheers,
> Magnus
> 
> 
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