Use of USCG differential GPS beyond nominal range

Abstract

The United States Coast Guard makes Differential GPS available to all maritime vessels in US coastal and inland waters to ensure 10 meter (2drms) horizontal accuracy. The Coast Guard guarantees this accuracy if the maritime user is within nominal range of the beacon transmitter. Maritime user's can often receive the differential correction beyond the nominal range, but the accuracy begins to degrade as baseline distance increases. After gathering differential corrections from varying distances, at different times of the day, at different latitudes, and different signal strengths, operational statistics have been calculated to describe the Differential GPS accuracy beyond the USCG's nominal range.