[time-nuts] Orbiting crystals

Lester Veenstra m0ycm at veenstras.com
Mon Jun 29 14:54:20 EDT 2009


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.


 
Lester B Veenstra  MØYCM K1YCM
lester at veenstras.com
m0ycm at veenstras.com
k1ycm at veenstras.com
-----Original Message-----
From: Lux, James P [mailto:james.p.lux at jpl.nasa.gov] 
Sent: Monday, June 29, 2009 7:36 PM
To: lester at veenstras.com; 'Discussion of precisetimeand frequency
measurement'
Subject: RE: [time-nuts] Orbiting crystals

> -----Original Message-----
.................
I think the idea was to look for jumps in a crystal oscillator when it goes
through the shadow of a total eclipse. My original suggestion was to look
for LEO satellites which had conveniently monitorable oscillator
frequencies. Someone else suggested using Inmarsat (because they have a
L-band pilot tone), but I think the Inmarsat birds are in Clarke orbit, so
you'd have to pick your ground station location (essentially in line with
the sun and the bird) to do the test.




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