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Re: [RC] long /limited distance - Truman Prevatt

The spec on GPS is 10 meters ( about 30 feet) 50% CEP. I believe it 50%, and I'm too lazy to drag out my spec. That means that 50% of the time the true location is within 10 meters of the calculated location. The military units are. This is only for point locations. The GPS system does not have a spec on distance measurements. The error in distance is a factor of a lot more than just the point position error. It's a function of how the position estimates are used to estimate distance, the samping rate, the complexity of the algorithm used, even the arithematic used in the processor.

So I would trust a lot of what GPS says - especially under foliage. The frequency GPS uses in not foliage penetrating.

But this whole discussion is pretty well down in the nits anyway. A max error of 2.5 miles is 5%. I would expect that there are very few trails out there that have a true distance withing 50% of what it measured to be - unless it's all driveable and the odemeter has been recently calibrated.

Truman

Paul Latiolais wrote:

So THAT means (following David's logic) that a 50 mile ride by definition must be OVER fifty miles,...because, as a practical matter, it must be measured with a certain limit on the level of accuracy. Hence you must always be over and round down to 50 miles, to insure that it is AT LEAST fifty miles.

Using a standard GPS, I think the level of accuracy is usually around 24 feet. So that would mean that a 50 mile ride would have to be measured as AT LEAST 50 miles plus 25 ft to guarantee that it was an official fifty mile ride.

-Paul
On Wednesday, May 26, 2004, at 07:17  AM, <heidi@xxxxxxxxxxxxxxx> wrote:



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At the end of the day maybe the definition of endurance isn't the length of
the ride but rather the spirit in which it is ridden. ~ Maryanne Stroud Gabani


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Replies
Re: [RC] long /limited distance, Paul Latiolais