Matthew Gates wrote: > Further to Ed's post, are there really GPS devices with one inch accuracy? > > I could imagine letting a device sit for some time, and then averaging the > position, which might lead to increased accuracy at the cost of > long "exposure" time... is that method used for surveying and so on?
He was referring to a combine using a DGPS system which has a base station at a fixed point on the farm whose location is well known. It then compares that known location to one calculated from the satellites in the normal and broadcasts the difference to the mobile received on the tractor/combine which uses the difference to correct it's own calculated position. What that allows you to do is to compensate for inaccuracy caused by local atmospheric conditions as you are generating a correction based on a local base station. Tom -- Tom Hughes ([EMAIL PROTECTED]) http://www.compton.nu/ _______________________________________________ Talk-GB mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-gb
