Theoretical Approach to Determining the 95% Probability of TTFF for the P(Y) Code Utilizing Active Code Acquisition

J.K. Holmes, N. Morgan, P. Dafesh

Abstract:	This paper presents a theoretical method of determining the probability of time to first fix (TTFF) for GPS P(Y) code. Commonly the specification for the TTFF is based on a TTFF time for a given time uncertainty and frequency uncertainty, to be achieved with a probability of, say, some probability say, 95% or 90%. Prior to this paper there has been no method available to compute this TTFF with an associated probability, consequently often times only the mean TTFF was computed and compared to a requirement. The TTFF is composed of a fixed time, a variable first code acquisition time and a variable read time for the clock and ephemeris data. It will be assumed in this paper that the P(Y) code is the signal being modeled to determine the TTFF. The interference is characterized as flat Gaussian noise of variable power spectral density over the 24 MHz centered on the carrier frequency.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	201 - 211
Cite this article:	Holmes, J.K., Morgan, N., Dafesh, P., "Theoretical Approach to Determining the 95% Probability of TTFF for the P(Y) Code Utilizing Active Code Acquisition," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 201-211.
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