[time-nuts] Slightly OT - GPS-Based Accurate Direction Finding
david at smithfamily.net.au
Thu Aug 26 14:09:31 UTC 2010
Thanks for all the interesting responses.
Some background - I'm needing an accuracy of 1 degree or better. The
experiments are using digital communication modes and sometimes aircraft
scatter so signals are regularly inaudible and often non-existent, so
peaking "by ear" is not usually an option.
I've paced out direction using a handheld GPS (GPSMap 60CSX) and this
gives reasonable results if there's a reasonable baseline. It's a bit
impractical when operating from a firetower though!
Using Sun/Moon/Stars is difficult when there's cloud. We've tried using
Sun RF Noise, but accuracy declines significantly when the sun is high
in the sky.
VOR is an interesting suggestion, but a very sharp (and large) antenna
would be needed and multi-pathing may cause problems.
So, my interest turns back to a GPS-based solution and the military
units suggested by Brooke look perfect ... except that they are most
likely a restricted export and unavailable to us Down Under.
Other links on Brooke's site have lead me to many papers researching
GPS-based attitude systems. I note that the Uni of Calgary have
developed a package called HEADRT+ that can take raw measurements from
several GPS mounted on a small baseline and produce attitude
information. This is the sort of thing I'm after, but I get the
impression that licensing costs are high.
As Atilla says, the software is probably not that fundamentally
complicated. However, the devil is possibly in the detail of aligning
sample timing, positioning ...
Any other suggestions?
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