A. G. Mourad and N. A. Frazier

Peer Reviewed

Abstract: POSITIONS OR DIRECTIONS in or on the deep oceans often cannot be determined with sufficient accuracy using ocean navigation systems now available. Present limitations on accuracy arise, in part, because of the lack of reliable marine references ystems,in cluding permanent marine control points. Control points are needed of the type that permit such a high degree of accuracy in land positioning. The accuracy and reliability of marine navigation systems could be improved if variations from some known standard could be determined. This paper discusseas standard system that could be established,viz., a marine geodetic calibration range. Positional fixes made with present systems are sometimesa mile or more in error. These systems could be evaluated, calibrated, and compared using the suggestedm arine geodetic range as a standard. The systems could be adjusted to minimize errors, thereby improving their accuracy and reliability. In one possible form, a geodetically constructed calibration range could extend parallel to a portion of the U. S. continental shelf and seaward to about 1500 miles from shore. The range, based on a bottom-referenced system tied to the U. S. land geodetic network, might consist of a network of lines or grids formed, for example, by t’hree to six permanent, and three temporary, ocean-bottom control points. In one configuration, identification of stations would be by acoustics ignalstr amsmitted by a set of three transponders on the sea bottom. Position on the ocean surface relative to the bottom transponders would be determined by solving a three-dimensional intersection problem, as is done in land geodesy. The most important measurements would be the line distances between the control points. It would be possible to measure these distances using aircraft line-crossing or satellite techniques. The final coordinates of the control points on the sea bottom could be determined (by applying geodetica djustment procedures)only after distance measuremensw ere completed. The relative accuracy of the proposed calibration range would be equivalent to 1:200,000, or about 50 feet along a 1500-mile calibration line.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 14, Number 2
Pages: 187 - 194
Cite this article: Mourad, A. G., Frazier, N. A., "IMPROVING NAVIGATIONAL SYSTEMS THROUGH ESTABLISHMENT OF A MARINE GEODETIC RANGE", NAVIGATION, Journal of The Institute of Navigation, Vol. 14, No. 2, Summer 1967, pp. 187-194.
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