"Dennis Lee Bieber" <wlfraed@ix.netcom.com> wrote in message news:13m4eefmegn7p1b@corp.supernews.com... > And you /should/ reference to some distinctive, and unlike to move, > landmark, as just recording a lat/long (or UTM) directly from the GPS > unit can still be off up to 10meters (though with WAAS and clear sky, > more likely the extreme drift is 3-5meter). Even a 5m error for your > recorded position, combined with a 5m error for someone coming back next > year, could result is their position being 30 feet away from where you > were standing... Outstanding suggestion! What you are doing is creating a local GPS corrector. Even if GPS were to go back to the +-100m induced error you would still be able to locate the item (momument, grave, etc) by offset from the major landmark. If you combine this with the use of UTM the math becomes very simple. "OK the fountain was YYYY, XXXX, now it's -10m +7m we just adjust the grave position the same amount and here we are... Hello great grandma. How you been?" -- Donald R. Newcomb DRNewcomb (at) attglobal (dot) net