C. San Giovanni, Jr. and E. Levinson

Peer Reviewed

Abstract: Current versions of SINS (Ships Inertial Navigation System) are capable of providing accurate navigational data over periods of several days without the need for intervening position fixes. It is desirable to provide a similar accuracy performance level for periods of several weeks. A primary factor limitirig such an extension of present capability is gyro drift, especially nonstationary (ramp-like) random components in the Z (vertical input axis) gyro. Tests have demonstrated that a gyro drift monitoring techniqtie known as H-modulation (or wheel speed modulation) can be used to bound such components of system gyro drift to levels compatible with system accuracy goals. The key to successful H-modulation is to minimize gyro torque disturbance variations that may be induced by the required changes in wheel speed. This paper describes the H-moddation technique, the design of the associated equipment, and some test results and system accuracy simulations. System implementation and data processing configurations are also discussed. Applications of H-modulation other than in SINS are indicated. It is concluded that H-modulation is a cost effective approach for providing significant extensions of SINS performance.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 22, Number 2
Pages: 135 - 151
Cite this article: Giovanni, C. San, Jr.,, Levinson, E., "H-MODULATION FOR LONG ENDURANCE MARINE INERTIAL NAVIGATION", NAVIGATION: Journal of The Institute of Navigation, Vol. 22, No. 2, Summer 1975, pp. 135-151.
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