GPS is used for weapon delivery, Mike so it must have a certain minimum level
of accuracy.
Yes, but I think that kind of accuracy by the military must be obtained
by some kind of secret sauce. I know that surveyors combine data with
ground stations and other means to get well into sub meter accuracy. You
will need one of these at least...and a sack of treasure.
<http://www.trimble.com/mappingGIS/geo-7-series.aspx?tab=Features_and_Benefits>
Your common commercial gps and/or phone can be trusted to be within the
10m circle "most" of the time and within 5m "some" of the time. But I
can't define "most" or "some" :). Vertical will usually be less accurate
I believe.
Here is a test we did to see if an iphone could be used to accurately
map our trails. Can you see where the tree cover is? (maybe previously
posted)
<http://www.interisland.net/watershed/mike/iphonetrack.jpg>
Red track is my Garmin. These tracks were compared with the corrected
Trimble which the NPS GIS guy used. Garmin was close enough, iphone fail.
Bottom line, don't expect miracles from your phone but most of the time
the data is accurate enough to be useful.
Now we just need to force certain cell providers to provide that data to
911 ... whole 'nuther story.
Mike
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