[time-nuts] OT - GPS and North

Tom Van Baak tvb at LeapSecond.com
Sat Nov 21 19:31:24 UTC 2009


> If the 
> positions of the satellites are known, as they must be to enable the 
> antennas position to be calculated, I think just an extra set of 
> calculations is necessary to indicate the direction to anywhere else on the 
> planet (or elsewhere) including the geographic poles.

Mike,

The calculations tell you where on the globe you are. Correct,
from this you can easily calculate angle and distance to either
pole.

But the receiver cannot "indicate" this angle. Meaning if you
hold a GPS antenna in your hand you may know you have
to aim 75 degrees and walk 5000 km to the North pole but you
still have no idea how to turn around to take that first step.

A static GPS receiver is a point device, not a pointing device.
On the other hand a magnetic compass is a pointing device,
not a point device. That's why some navigation units combine
both.

If you just want to travel then as Confucius say: journey of a
thousand miles begins with single step. But if you want to
reach a particular destination then journey of a thousand
miles must begin with single step in correct direction. ;-)

/tvb




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