Interesting point and one that was discussed quite a bit a couple of years
ago.  Assuming you are correct then that would say that GPS indicated speed
is only correct when traveling a straight road.  And what does that say
about the ground track trace most, even older GPS units, store?  And what of
the newer GPS units , especially those designed for use in vehicle?  Do they
provide more accurate data, or, like my older hand held unit (Magellan 4000)
give bad info on the odometer function?
BTW, not trying to get an argument going here, just really curious about
other peoples real world experience with hand helds vs. GPS units sold for
use in vehicles vs. laptop software/GPS combinations.
Guess I'll have to set up both the handheld and the laptop and run them
together for a hundred miles or so and then compare.

On 8/4/06, Ken Lake <ken.lake@alereon.com> wrote:
>
> RE: GPS distance.
>
> This is because the GPS calculates the straight line distance between
> the starting and ending points.  Although it calculates its exact
> location several times a second and uses that to determine its speed, it
> does not store the incremental distances between locations, which it
> would need to calculate total distance.  Hence it can plot your trip,
> give you the speed, current location, but distance from starting is
> always wrong (compared to how you got there)
>
>
>