GPS phased arrays aren't new, nor is it necessary to physically steer
the antennae within the aray:
http://www.navsys.com/papers/0005004.pdf
Bruce
Magnus Danielson wrote:
On 03/08/2011 05:22 AM, Hal Murray wrote:
Since you are after timing off of the sat's, having antennas that move,
either physically or electrically seems like a problem. Any shift in
the
effective antenna location as you tracked the satellite would be
"exciting"
to compensate for. There was an early paper published based on doing
this
(early 80's).
You can correct for the antenna orientation. (That's what software
is for.
:) Radio astronomers have been doing it forever.
I think it's simple, at least in the nice/common cases. If the antenna
geometry has a point that everything swivels around, consider that to
the the
location of the antenna. I think that covers the typical alt-az mount:
http://en.wikipedia.org/wiki/Altazimuth_mount
The point is where those two axes intersect. Now just fudge the coax
delay
to correct for the time/distance from the real antenna location to that
point. That's the before location coax delay (in there with the
ionospheric
delay) rather than the post GPS antenna-to-box delay.
Of course, it gets a bit more complicated than that if you want to track
several satellites in real time. That probably takes an antenna per
satelite. But again, VLBI geeks have been doing that sort of math
for ages.
You would need to have a DGPS input stream generated in order to
compensate sat for sat. If you don't have a DGPS input to the GPS
receiver you are fairly stuck with the shifts...
Cheers,
Magnus
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