[time-nuts] Making a HP 10811 better

[Bob Camp]

Hi

I suspect all of that's not entirely accidental. 

If tidal shifts were easily seen on stable OCXO's, there would be a lot more attention paid to acceleration compensation. 

OCXO's with parts in 10^-12 / day aging rates are not uncommon. Just leave them continuously on power for a long time. A big fat crystal inside also helps a bit :)......

If you got a significant chunk of a few parts in 10^-12 from tides, people would have noticed - and complained. 

Bob


On Mar 28, 2010, at 8:49 PM, Tom Van Baak wrote:

> Warren,
> 
> No, measuring an oscillator every second will not help.
> 
> The change in g = ~9.81 m/s due to tides is about 1e-7 over
> part of a day. So g changes by about 1e-8 per hour; that's
> about 1e-12 per second.
> 
> Now df/dg for a 10811 is on the order of 1e-9. So the tidal
> effect of the sun/moon will change a 10811's frequency by
> about 1e-12 x 1e-9 = 1e-21 per second, which is about a
> billion times below the short-term noise level of a 10811.
> 
> Now the reason pendulum clocks can "detect" tides (and
> only a few of the world's best have ever done so) is that
> their frequency is directly dependent on g. That is, df/dg
> for a pendulum clock is 0.5! By contrast df/dg for a 10811
> quartz oscillator is around 0.000000001.
> 
> /tvb
> 
> 
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