Russell McMahon <apptech@PARADISE.NET.NZ> wrote:
> > OK, so I was asked to put together a GPS speedometer. I thought it would
> > be fairly simple, but now I'm not so sure I can expect accuracy without a
> > fair amount of complexity. Is it worth the trouble?
>
> Speed can be deduced from position variation with time BUT you have a speed
> signal already available based on phase shift of received signals. It would
> be trivial to use this for a speedometer function and you could add code to
> make an informed decision about whether something "intetresting" was
> happening.
>
> Given that it's so easy to try, why not try it and see how it works out.

Trivial? Easy to try? What kind of receivers do you have access to that
provide phase information?

Even if you could get it, you'd need to compensate for the ~5800 mi/hr
velocity of the satellites themselves before you could determine anything
about the receiver velocity.

-- Dave Tweed

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