[time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

jimlux jimlux at earthlink.net
Fri Nov 17 22:40:23 EST 2017

On 11/17/17 5:16 PM, Hal Murray wrote:
> kb8tq at n1k.org said:
>> Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk”
>> accuracy with a GPSDO. Much easier to obtain and set up in a school
>> environment. The key will be orbit estimation for the +/- doppler part of
>> it.  Orbit estimation is not quite a slam dunk sort of thing. The GPSDO
>> would also give accurate location. Even with good orbit data, the solution
>> still requires a good location estimate.
> What is the orbital period?  It would be fun to plot the Doppler over time
> and see if you can get something that looks like a big chunk of an orbit.
> Ugh.   What is the Doppler due to the Earth's rotation?

not huge.. Earth is 40,000 km circumference (thank you Napoleon and the 
Cassinis), so at the equator the velocity is on the order of 500 m/s

Doppler is about 600 Hz from earth rotation.

1ppm at mid latitudes

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