Accession Number : ADP004578

Title :   Separating the Variances of Noise Components in the Global Positioning System,

Corporate Author : NATIONAL BUREAU OF STANDARDS BOULDER CO TIME AND FREQUENCY DIV

Personal Author(s) : Allan,D. W. ; Weiss,M.

Report Date : 02 APR 1984

Pagination or Media Count : 17

Abstract : Central to the success of the GPS program is the ability to model the frequency stability characteristics of the its various components. A persistent challenge in evaluating the Global Positioning System in the separation of the errors of the satellite clocks from those due to the satellite ephemeris errors and/or the signal propagation delay errors. This information is important when one tries to improve the performance of the Global Positioning System. It is necessary to know if a particular component of the system meets specification and which component(s) limits performance. Although one cannot separate the errors themselves, a method has been developed whereby the Allan variances of critical components to the GPS can be separated. Using a reference clock such as UTC(NBS) or UTC(USNO), for example, the fractional frequency stability of each of the following can be separated from each of the others: the reference clock, the space vehicle clock, the GPS clock, the clock upload correction, the ephemeris and the propagation delay. This technique has the potential to significantly assist in properly setting the parameters to obtain optimum performance from the Global Positioning System e.g. setting the Kalman filter parameters. Results will be given showing some interesting surprises in the characteristics of the system. (Author)

Descriptors :   *TIME SERIES ANALYSIS, *NOISE, *ERROR ANALYSIS, *GLOBAL POSITIONING SYSTEM, COMPUTATIONS, VARIATIONS, CHARTS, KALMAN FILTERING

Distribution Statement : APPROVED FOR PUBLIC RELEASE