| 摘要 |
A preferred embodiment permits the safe navigation of a channel or harbor by a ship. A preferred embodiment includes a ship-borne system having a first global positioning system (GPS) receiver and a second fixed reference station with a GPS receiver. Both GPS receivers have GPS signal receiving antennas. Earth orbiting satellites of the GPS maintain communication at both locations via the two receive antennas. A broadcast radio transmitter at the reference station transmits a received GPS signal to the ship-based GPS antenna for receipt by the ship's separate radio receiver and processing by a computer. Using known navigation chart information on the water depths within a body of water, channel or harbor, known marine surveyor data, including the phase center of the ship-borne GPS receive antenna, and the two separately received GPS signals, the ship's keel clearance referenced to a known chart datum is calculated at one second intervals.
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