Aren't there electronic units that compensate for static conditions?? Not
sure if they make them now, but remember reading about flux gate compass'
in Nuts and Volts.


At 09:21 PM 4/19/04, you wrote:
>PicDude wrote:
>
>>Not surprisingly, when running a compass sensor in my car, I'm running into
>>interference (incorrect sensor outputs) from all the other electronics and
>>metal in the car.
>
>>Anyone know where these sensors are typically mounted in a vehicle?
>
>  Short answer:  Use GPS, you need to be moving, but it's a small price to
> pay.
>
>  Longer answer:
>  Basically, it should be mounted anywhere where it will work within the
>calibration limits of the compass.  If it doesn't have calibration adjustments
>(mechanical or electronic) don't even try using it.
>
>  My magnetic compass came with instructions to point the vehicle to north
>(using other known methods) some distance from any surrounding metal, overhead
>wires etc, then go though the calibration adjustment (point NSE & W) till it
>reads correctly.
>
>  I had it down to within a few degrees.
>
>  In use, it was a different story.  Every time you remove or install a piece
>of equipment in your vehicle, you have to check it doesn't interfere with the
>compass, and re-calibrate if it does.
>
>  While sitting at traffic lights, the adjacent lane (if moving) would cause
>the compass to swing back and forth each time a car passed me.
>
>  While driving in a steady straight line on the freeway (no other surrounding
>cars) the compass would sometimes swing back and forth due to surrounding
>steel
>barriers and such.
>
>
>  In the end, I found it so useless (because I couldn't guarantee the "purity"
>of my environment where I needed it) that I relied on GPS only.  The compass
>was for backup just in case GPS went down.
>
>  Now, if I need backup, I carry two GPS recievers.
>--
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>
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