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

Magnus Danielson magnus at rubidium.dyndns.org
Sat Nov 18 05:38:08 EST 2017


On 11/18/2017 02:16 AM, 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?

You need to compensate for your position, because it would lower due to 
longitude naturally.

Yeah, and then the moon isn't in perfect circular orbit either.

The sat is also in a not so perfect orbit, so it would also needed to be 
measured and characterized.

Fun problem.

I realized that my on the fly least square algorithms would be nice to 
adapt to this problem.


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