SIMPLE GENERAL PURPOSE MARINE NAVIGATION USING NAVIGATION SATELLITE DATA

John E. Cutting

Peer Reviewed

Abstract:	A SIMPLE TECHNIQUE, applicable to general purpose marine navigation, and utilizing navigation data from satellites is presented. A single position fix requires only a means of receiving and interpreting navigation data, using a specially prepared table or graph, and employing conventional navigation charts and plotting procedures. No automatic computation is required. It is assumed that a navigator has an a priori estimate of position, however crude, and access to specially prepared tables or graphs which provide transmission time as a function of satellite altitude and great circle distance from subsatellite point to user. It is also assumed that the navigation signal received from a satellite contains information on satellite loca- Con and time of transmittal. After drawing a line of azimuth from estimated position to satellite geographic position on the chart and determining the corresponding distance, a transmission time may be obtained and then used to synchronize the receiver oscillator and roughly calibrate the system. Then two parallel lines may be constructed; one through the estimated position normal to the line from the subsatellite point and the second displaced by a distance corresponding to a fixed time increment. Using this synchronization and calibration information similar lines may be drawn with respect to two other satellites. Diagonals of the resultant parallelograms are straightline approximations of hyperbolic lines of position since they correspond to loci of constant range differences. Intersections of the lines of position provide an improved estimate of position. Preliminary analysis indicates that a time measurement resolution of one part in l06 will yield an estimate of position within one nautical mile. Other sources of error, such as atmospheric uncertainties and construction errors also contribute to the position error. An iterative procedure will reduce bias errors which are directly related to initial estimate error.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 16, Number 2
Pages:	173 - 181
Cite this article:	Cutting, John E., "SIMPLE GENERAL PURPOSE MARINE NAVIGATION USING NAVIGATION SATELLITE DATA", NAVIGATION: Journal of The Institute of Navigation, Vol. 16, No. 2, Summer 1969, pp. 173-181.
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