Robust real-time wide-area differential GPS navigation

US5828336A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Thomas Patrick Yunck · Pasadena, US
• William I. Bertiger · Altadena, US
• Stephen M. Lichten · Pasadena, US
• Anthony J. Mannucci · Pasadena, US
• Ronald J. Muellerschoen · Pasadena, US
• Sien-Chong Wu · Torrance, US

Key dates

• Filing date: Mar 29, 1996
• Grant date: Oct 27, 1998
• Expiry date: Mar 29, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S19/27
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The present invention provides a method and a device for providing superior differential GPS positioning data. The system includes a group of GPS receiving ground stations covering a wide area of the Earth's surface. Unlike other differential GPS systems wherein the known position of each ground station is used to geometrically compute an ephemeris for each GPS satellite, the present system utilizes real-time computation of satellite orbits based on GPS data received from fixed ground stations through a Kalman-type filter/smoother whose output adjusts a real-time orbital model. The orbital model produces and outputs orbital corrections allowing satellite ephemerides to be known with considerable greater accuracy than from the GPS system broadcasts. The modeled orbits are propagated ahead in time and differenced with actual pseudorange data to compute clock offsets at rapid intervals to compensate for SA clock dither. The orbital and clock calculations are based on dual frequency GPS data which allow computation of estimated signal delay at each ionospheric point. These delay data are used in real-time to construct and update an ionospheric shell map of total electron content which …