GPS Velocity Damping and Its Effect on SINS Performance

John J. Carvill III

Abstract:	For more than twenty years the Electromagnetic (EM) Log has provided a satisfactory velocity damping reference to the ship’s inertial Navigation System (SINS). The EM Log does have some limitations in that it does not provide an accurate speed reference to SINS 100% of the time. This has been factored into SINS performance expectations in the past and has been accepted as a fact of life. However, with the introduction of GPS, this accepted EM Log/SINS performance characteristic may become obsolete. Initial data from sea trials in two aircraft carriers indicates that either GPS velocity damping alone, or in conjunction with EM Log damping, provides a surface ship SINS performance enhancement that is not achieved when SINS is only interfaced to EM Log. If additional data proves this to be a permanent condition, then two benefits become evident. The first of these is that surface ship SINS performance can be improved cost effectively through utilization and possibly enhancement of this GPS/SINS velocity operation. This may obviate what would typically require a more expensive inertial technology upgrade. Second, if GPS can be used independently, EM Log may transition to a backup speed reference in some surface ship applications. This Implies that cost effective EM Log reliability and maintainability changes might be implemented rather than the changes associated with more expensive research and development efforts.
Published in:	Proceedings of the 49th Annual Meeting of The Institute of Navigation (1993) June 21 - 23, 1993 Royal Sonesta Hotel Cambridge, MA
Pages:	655 - 664
Cite this article:	Carvill, John J., III, "GPS Velocity Damping and Its Effect on SINS Performance," Proceedings of the 49th Annual Meeting of The Institute of Navigation (1993), Cambridge, MA, June 1993, pp. 655-664.
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