Re: Didn't they hear?miss_mellie_bFebruary 9 2007, 16:53:31 UTC
Our GPS equipment has sub-meter accuracy, but in order to achieve that accuracy, the data must be post-processed through a program that will triangulate the location of the satellite at the time of the survey, a fixed base station and the GPS equipment.
If the data is not triangulated, there is a GPS error factor of 10-20 feet, which in the case of pipeline problem locating, is unacceptable. Our last four surveys were done but not post-processed, plus the field guys did not always use the sub-meter accuracy program, so in some locations, the actual location of a pipeline problem was 90 feet from the GPS coordinates.
Re: Didn't they hear?seumas_13February 15 2007, 03:09:49 UTC
eek!
I understoof that triangulation shouldn't be necessary anymore. Certainly it shouldn't be anywhere close to 10 feet off if you have a sub-meter GPS receiver.
But I don't work with it, so I am certain you know more about it than I do. I guess I heard (or interpereted) wrong.
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If the data is not triangulated, there is a GPS error factor of 10-20 feet, which in the case of pipeline problem locating, is unacceptable. Our last four surveys were done but not post-processed, plus the field guys did not always use the sub-meter accuracy program, so in some locations, the actual location of a pipeline problem was 90 feet from the GPS coordinates.
This is not fun.
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I understoof that triangulation shouldn't be necessary anymore. Certainly it shouldn't be anywhere close to 10 feet off if you have a sub-meter GPS receiver.
But I don't work with it, so I am certain you know more about it than I do. I guess I heard (or interpereted) wrong.
:-(
Have a Cookie.
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