> Just curiouse on the compass being affected by car chassis, current flows
> etc. How much potential error are we practicly talking about? Less that 5
> degrees? Potentially 45 or 90 degrees?
In theory the error could exceed 90 degrees, if the compass were right next
to a wire carrying a significant amount of current.
It's been too long, I'm not sure of the numbers now. I used to work with
some people that were trying to use a (solid state) magnetic compass for
vehicle heading, and what I recall is that the optimum location usually
resulted in only 10 or 15 degrees variation, worst case after calibration in
place. This is after correcting for the error between true north and
magnetic north, which varies with location and year and can add another
10-15 degrees of error. But they could even tell when the doors were open,
by the change in magnetic field of the car.
Randall
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