GPS Attitude Determining System for Marine Navigation

Debra L. Diefes, Geoffrey G. Hazel, and Darrell F. Greenlee

Abstract:	Under contract with the U.S. Coast Guard, Adroit Systems, Inc. has developed a low cost, GPS based Attitude Deter- mining System (ADS) for marine navigation. The Coast Guard will use the system for general navigation, as well as hydrographic surveying, ice breaker navigation, and posi- tioning buoys or other objects. Following a successful sys- tem demonstration validating the concept design, a prototype system has been produced and tested. This suc- cessful prototype has led to a commercial product for marine navigation, TRIADS. The ADS navigation system makes good use of the full sat- ellite constellation. Having 6 to 8 satellites available serves two very important objectives. First, approval for GPS ADS as a primary navigation system can be pursued now that the constellation is complete. Second, this allows the optimum satellite constellation to be selected based on the attitude of a platform. Having more than the required num- ber of satellites available not only enhances system accu- racy and robustness, but also enables the system to perform integrity checks in the form of receiver autonomous integ- rity monitoring (RAIM). The Coast Guard is currently studying the use of integrated navigation systems, such as the ECDIS (Electronic Chart Display and Information System), to incorporate many navigation systems a single user interface. GPS navigation enhances radar stability by providing instantaneous head- ing to the radar during dynamic maneuvers. GPS derived attitude is a large contributor to this system, as it suffers no degradation at the higher latitudes, unlike a magnetic or gyrocompass. This paper describes the prototype system, built using com- mercial off-the-shelf (COTS) components, and presents system performance and test results. The opportunities provided by such a system now that the constellation is complete will also be discussed.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	649 - 655
Cite this article:	Diefes, Debra L., Hazel, Geoffrey G., Greenlee, Darrell F., "GPS Attitude Determining System for Marine Navigation," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 649-655.
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