How accurate is the reading for GPS in iPhone's SDK? -

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using iphone's sdk gps api, how accurate can get? within few meters or kilometers? i'm interested in accuracy when indoor. my software used in door.

the best possible accuracy seems 9 meters. common values (outdoor, coverage) 17 m, 23 m , 49 meters. trees covering sky you'll stay under hundred meters, hardly accurate enough gis or that.


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