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Index of Subjects Steve, What I learned from a surveyor who needs about 1 foot accuracy (maybe different than what he meant): Find a geodetic marker nearby and measure its location using your GPS. This will give a correction. There is expensive equipment which will transmit this correction real time to the GPS. How quickly this correction changes over time is unclear to me. Stephen Shaw wrote: > Hi Fritz or others, > Thanks -- it sounds like a good deal. > > What's the best GPS spatial resolution you can get in the field these > days, for > close-scale local mapping? My recollection is that a few years ago it was > quoted as no better than about 15 feet, even with several satellites > optimally > in view, which is a bit coarse for an application I was thinking of. Is it > still in the same ballpark or has it improved? > > If you were to stand in one place and do repeated determinations and then > average these numbers, would you get closer to determining more accurate > spatial coordinates for that spot? You might expect this if the source of > spatial uncertainty were `random` internal noise in the receiver, or > something > similar. Or does the source of uncertainty in the GPS reading lie > elsewhere? I > think I asked this once before a few years ago but don't remember getting a > clear reply, and never bought a unit. There was even a story that the > spatial > resolution is intrinsically much finer than is available to the public, but > that the US military has deliberately detuned the public output so it > was less > precise, presumably so it could not be used for accurate nefarious > targetting > -- I'm guessing that this was an urban legend? > > Steve > (Halifax)
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