GPS Composite Clock Analysis. (25th November 2007)

• Record Type: Journal Article
• Authors: Wright, James R.
• Other Names: Matsakis Demetrios Academic Editor.
• Is Part Of: International journal of navigation and observation. Volume 2008(2008)
• Publication Date: 2007-11-25
• Subjects: Navigation -- Periodicals; Remote sensing -- Periodicals; Geographic information systems -- Periodicals; Global Positioning System -- Periodicals; Earth sciences -- Periodicals; Environmental monitoring -- Periodicals; Navigation; Télédétection; Systèmes d'information géographique; GPS; Sciences de la terre; Environnement -- Surveillance; Earth sciences; Environmental monitoring; Geographic information systems; Global Positioning System; Navigation; Remote sensing; Periodicals; Electronic journals; 629.045
• DOI: 10.1155/2008/261384
• Languages: English
• ISSNs: 1687-5990

Abstract

Abstract : The GPS composite clock defines GPS time, the timescale used today in GPS operations. GPS time is illuminated by examination of its role in the complete estimation and control problem relative to UTC/TAI. The phase of each GPS clock is unobservable from GPS pseudorange measurements, and the mean phase of the GPS clock ensemble (GPS time) is unobservable. A new and useful observability definition is presented, together with new observability theorems, to demonstrate explicitly that GPS time is unobservable. Simulated GPS clock phase and frequency deviations, and simulated GPS pseudorange measurements, are used to understand GPS time in terms of Kalman filter estimation errors.