Hi,

> > How about doing periodic GPS nav, and using inertial navigation
> > in the interim.  If you can tolerate the accumlated errors between
> > GPS fixes, might be a way to go.  Accelerometers are getting
> > small and cheap
>
> How large would you expect the errors to be ? He's aiming for
> 10 - 15m positional accuracy updated every 15 seconds

    The GPS errors alone are bigger than that ! In my tests my apartment
windows moves more than 30 meters ! The cumulative errors from the
acelerometer can get pretty big but if the movement is reasonably constant
it might work. The error tends to be quite random if you make frequent
readings and integrate them well, so part of it will cancel out.

Best regards,
Alexandre Guimaraes

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