Precise Marine Positioning Using the Global Positioning System (GPS).
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The development of the Global Positioning System GPS has led to the possibility of positioning marine platforms with great accuracy. This report describes position computations made from GPS observations aboard a ship and the evaluation of the accuracy and precision of a Texas Instruments TI-4100 GPS Receiver at sea in a low dynamic mode. The observed pseudoranges were corrected and smoothed by Doppler count, and then were used to compute position using an eight-state Kalman filter. A comparison is made between the ships position obtained by GPS receiver and by Del Norte Trisponders. Data covering a period of 3600 s were processed and compared, yielding a total of 3171 s of data points from both positioning systems, which consisted of 2740 s of data with four satellites present and 431 s of data with three satellites. The mean of the root-mean-square differences between launch positions determined by mean of GPS satellites and by Trisponder was found to be or - 11 m when four satellites were available and or - 21 m when only three were presents. Some 29 percent of the time, the GPS positions and Trisponders positions had similar accuracy. Author.
- Marine Engineering