[time-nuts] Orbiting crystals

Magnus Danielson magnus at rubidium.dyndns.org
Mon Jun 29 15:05:18 EDT 2009


Lester Veenstra wrote:
> Now this begins to make some sense; 
> 
> Of course the geosync satellites do go into eclipse season trice a year,
> during which each day the satellite is passing through the Earth's shadow
> for a variable period.  
> 
> To pass though the shadow of a solar lunar eclipse, the eclipse would have
> to be visible on the ground at satellite sub-satellite point ( nominal, the
> equator). For the Inmarsat's this would be at:
> 
> 24.8 E
> 25.1 E
> 64.5 E
> 109.0 E
> 143.5 E
> 178.1 E
> 218.0 $
> 261.9 E
> 262.4 E
> 306.0 E
> 344.5 E
> 
> But, since there are satellites virtually anywhere along the arc, there is
> no reason to restrict observations to INMARSAT. But INMARSATs do provide a
> easy target  for an observer with simple L-Band equipment.
> 
> Of course I would expect to see a shift in an onboard crystal frequency (but
> not a "jump") simply from the thermal changes.

It was assumed that the crystals was locked to Cesium or Rubidium, and 
hence it would chase up the error.

Cheers,
Magnus




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