[GRLUG] OT, but GPS, anyone?

[Collin Kidder]

Hmm.. First off, I suppose I should suggest that it's a lot easier to 
just get a magnetic compass chip that will point you toward magnetic 
north. If the stationary piece of equipment is truly stationary then you 
can then correct for the offset from magnetic north from true north 
according to the position on the Earth. Of course the magnetic pole 
isn't stationary so that might create too much uncertainty for you. 
You'd have to try to occasionally recalibrate. It's a lot cheaper and 
easier option than dual GPS though.

But if that doesn't do it for you then I suppose the absolute minimum 
spacing is the GPS resolution which is normally 1 meter. Anything under 
that and gps positional uncertainty will overtake your sample accuracy. 
It would be best to space at least twice the GPS resolution but the 
farther apart the two points are the better your accuracy.



On 8/26/2009 11:53 AM, L. V. Lammert wrote:
> Got a project where we need to establish a true N indiation on a
> stationary piece of equipment using a Linux host, .. if we had two GPS
> units, say, 25' apart it would be trivial (take the differential between
> the two readings and any positional errors cancel, producing a reference
> vector that can then be corrected to true N).
>
> Need to determine the *minimum* spacing between two units - don't
> suppose anyone knows anything about this sort of technology, or could
> point us in the right direction?
>
> 	TIA,
>
> 	Lee
>
> ==============================================
>   Leland V. Lammert            lvl at omnitec.net
>    Chief Scientist        Omnitec Corporation
>   Network/Internet Consultants www.omnitec.net
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