Accession Number:

ADA517832

Title:

Optimal Time Transfer

Descriptive Note:

Conference paper

Corporate Author:

ANALYTICAL GRAPHICS INC EXTON PA

Personal Author(s):

Report Date:

2009-11-01

Pagination or Media Count:

13.0

Abstract:

We have designed an optimal time transfer algorithm using GPS carrier-phase and pseudorange measurements. This will enable the near-real-time estimation of the difference between the phase of a stable real-time UTC ground clock attached to a GPS ground receiver and the phase of each NAVSTAR spacecraft clock in the ensemble of GPS spacecraft. We propose a master filter MF to drive multiple instances of spawned filters SF and fixed-epoch smoothers FES. The MF is designed to map all GPS carrier-phase measurement information of each GPS ground-stationNAVSTAR pass into the complete MF state estimate of all NAVSTAR parameters and all station parameters, with all serial correlations and all cross-correlations accounted for. Each SF runs forward with time while the FES linearly maps measurement information backwards to fixed epochs for individual NAVSTAR spacecraft. FES estimates are then folded into the MF as pseudo-measurements. The resulting time-transfer algorithm is an autonomous forward-running sequential estimator, with no state-sized matrix inverse calculations required.

Subject Categories:

  • Test Facilities, Equipment and Methods

Distribution Statement:

APPROVED FOR PUBLIC RELEASE