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Cellular forums Home > Archive > Garmin GPS > March 2008 > Disagreement between units
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Disagreement between units
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| Michael Koblic 2008-03-25, 4:34 am |
| My eTrex Venture underestimates the lengths of routes when compared
side-by-side with a new Forerunner 305, usually by several hundred meters.
What are the possible reasons for this? Which of the units is more likely to
be correct?
--
Michael Koblic,
Campbell River, BC
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| Simon Slavin 2008-03-29, 10:33 pm |
| On 24/03/2008, Michael Koblic wrote in message
< 13uh0kl426uhv2f@corp
.supernews.com>:
> My eTrex Venture underestimates the lengths of routes when compared
> side-by-side with a new Forerunner 305, usually by several hundred
> meters. What are the possible reasons for this? Which of the units is
> more likely to be correct?
The problem with lengths of routes is all about the corners. Bends in
routes make calculating the distance very difficult. If you have two unit
side-by-side, then you can perform a useful experiment: use them both on a
route as straight as you can manage it: find a straight road or something.
Then see if they still disagree to the same extent.
The length of the route is the total of the distances between successive
points. So how is your unit set to plot points ? Does it plot a new
point at regular time intervals, or when the new point is more than a
certain distance from the last point ?
Simon.
--
http://www.hearsay.demon.co.uk
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