A Total Estimator of the Hadamard Function Used for GPS Operations

Dave Howe, Ron Beard, Chuck Greenhall, F'rancois Vernotte, Bill Riley

Abstract:	We describe a method based on the Total deviation approach whereby we improve the confidence of the estimation of the Hadamard deviation that is used primarily in GPS operations. The Hadamard-total deviation described in this paper provides a significant improvement in confidence indicated by an increase of 1.3 to 3.4 times the one degree of freedom of the plain Hadamard deviation at the longest averaging time. The new Hadamard-total deviation is slightly negativity biased with respect to the usual Hadamard deviation, and T values are restricted to less than or equal to T/3, to be consistent with the usual Hadamard’s definition. We give a method of automatically removing bias by a power-law detection scheme. We review the relationship between Kalman fiber parameters and the Hadamard and Allan variances, illustrate the operational problems associated with estimating these parameters, and discuss how the Hadamard-total variance can improve management of present and future GPS satellite clocks.
Published in:	Proceedings of the 32th Annual Precise Time and Time Interval Systems and Applications Meeting November 28 - 30, 2000 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	255 - 268
Cite this article:	Howe, Dave, Beard, Ron, Greenhall, Chuck, Vernotte, F'rancois, Riley, Bill, "A Total Estimator of the Hadamard Function Used for GPS Operations," Proceedings of the 32th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, November 2000, pp. 255-268.
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