[time-nuts] Using GPS for space-based instrument

[Brooke Clarke]

Hi Karl:

Tom Clark may be the person who can answer that question.

I seem to remember that the very first GPS satellites had antennas only aimed 
at the Earth, but because many satellites now use GPS for a number of functions 
they also radiate some signal away from the Earth.

In addition there's the question of getting a license for a military grade GPS 
receiver.  Note that civilian grade GPS receivers have limits on elevation, 
speed, acceleration and jerk which prevents them working in military aircraft, 
missiles and space environments.  It may be that the your satellite already has 
a GPS receiver for some other purpose so that you only need access to the 1 PPS 
or 10 MHz output?

Have Fun,

Brooke Clarke
http://www.prc68.com

Strauss, Karl F wrote:
> I've been tasked (or was it I was volunteered?) to do some basic design & definition work on an ultra-stable master frequency system for a proposed instrument that is currently planned to be in an Earth-trailing orbit.   Given the first order accuracy requirement of 1 part in 1E-10, my first thought was to grab the GPS timing signal.
> 
> Sorry for the newbie questions here:    a) Do all satellites in the constellation broadcast a signal into space  (as opposed to, say,  bouncing off some ionospheric boundary layer); and b) is there some website/technical paper describing expected signal strength for these space-radiated signals?
> 
> Again, apologies to all for the Newbie Q's.  Hopefully this will be a fun topic of discussion
> 
> Thanks
> 
> Karl
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