In a message dated 1/5/00 11:41:40 AM, mvheim@studiolimage.com writes:
<< Having used a GPS satellite receiver for navigation at sea I can't
imagine that this would really work as advertised. For one thing you
aren't getting continuous data, which makes any calculations of
instantaneous speed pretty shaky. As it updates the display every few
seconds, you get varying readouts along these lines: 6.1 knots, 5.9, 7.4,
0.0, 5.5, 3.7, etc. Part of the problem is that it's redoing the whole
position calculation from scratch each time, with a 30-meter error
radius. >>
GPS can provide this information, it depends on the power of your onboard
computer to extract it. It is done in aviation. Further, a new generation
of "correction" systems, called the Wide Area Augmentation System for the
enroute environment, will nail the accuracy down to a couple of meters.
These are in the works for the developed nations, and use in part signals
from geosynchronous communications satellites operated by Inmarsat.
So the unfortunate conclusion is that it is possible. Sad, ain't it.
Jay Donoghue
72 MGB
66 Mustang
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