Accession Number : ADP009114

Title :   A Comparison of GPS Broadcast and DMA Precise Ephemerides,

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

Personal Author(s) : Weiss, Marc A. ; Petit, Gerard ; Shattil, Steve

Report Date : 02 DEC 1993

Pagination or Media Count : 14

Abstract : We compare the broadcast ephemerides from Global Positioning Satellites (GPS) to the postprocessed ephemerides from the Defense Mapping Agency (DMA). We find significant energy in the spectrum of the residuals at 1 cycle/day and higher multiples. We estimate the time variance of the residuals and show that the short term residuals, from 15 min, exhibit power law processes with greater low frequency perturbations than white phase modulation. We discuss the significance of these results for the performance of the GPS Kalman filter which estimates the broadcast orbits.

Descriptors :   *EPHEMERIDES, *NAVIGATION SATELLITES, CYCLES, ESTIMATES, LOW FREQUENCY, MODULATION, PERTURBATIONS, PHASE MODULATION, RESIDUALS, TIME, GLOBAL POSITIONING SYSTEM, KALMAN FILTERING.

Subject Categories : Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE