[time-nuts] GPS at 60,000 feet

Jim Lux jimlux at earthlink.net
Sat Feb 2 14:51:37 UTC 2013


On 2/2/13 5:07 AM, Grant Hodgson wrote:
> GPS has already flown in space several times; one of the well-publicized
> occurrences is when NASA sponsored an experiment to put a 6-channel
> Trimble receiver on the ill-fated AO-40 amateur radio satellite which
> launched in 2000.

>
> This satellite had a highly elliptical orbit, with perigee of 1000km and
> apogee of 60000 km - well outside the GPS constellation.
>
> The GPS experiment was one of the first experiments to be tested on this
> satellite and some useful results were obtained before the satellite was
> lost due to technical failures in 2004.

of course I don't know that one would count it as a resounding success.. 
basically they were able to acquire and track the signals:
"...Although the receiver has not returned any point solutions, there 
has been at least one occasion when four satellites were tracked 
simultaneously, and this short arc of data was used to compute point 
solutions after the fact. ..." (from the abstract)


The paper does describe other "above the GPS constellation" 
experiments.. TEAMSAT/YES, EQUATOR-S. Both those required "helping" the 
receiver (Trimble TANS-II for the former, Motorola Viceroy for the 
latter) so I don't know if that qualifies as the OP question "consumer 
handheld GPS"

  "Falcon Gold" collected raw samples which were the post processed on 
the ground. Not a consumer receiver by any means.

The article also points out that they had to modify the software in the 
AO-40 trimble TANS Vector receiver.

That receiver is hardly a handheld consumer receiver, also:
"The Trimble Advanced Navigation Sensor (TANS) Vector is a four-antenna, 
six-channel GPS receiver system which provide s standard or 
differentially corrected (DGPS) position, velocity, time and attitude 
(azimuth, pitch, and roll) to external data terminals."

http://trl.trimble.com/docushare/dsweb/Get/Document-19330/20997-00-C.pdf



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