California Institute of Technology

The United States of America As Represented by the Administrator of the

William I Bertiger

Yoaz E Bar-Sever

Stephen M Lichten

Sien-Chong Wu

Ronald J Muellerschoen

Kenneth Hurst

Larry J Romans

Catherine Thornton

Geoff Blewitt

Nathaniel E Harvey

Jan P Weiss

Thomas Yunck

Mark A Miller

Michael Heflin

Angela R Dorsey

James Zumberge

Anthony J Sibthorpe

Miquel Garcia Fernandez

Wenwen Lu

Jason Gross

Kevin J Miller

Thomas Patrick Yunck

Anthony J Mannucci

Novel methods and systems for the accurate and efficient processing of real-time and latent global navigation satellite systems (GNSS) data are described. Such methods and systems can perform orbit determination of GNSS satellites, orbit determination of satellites carrying GNSS receivers, positioning of GNSS receivers, and environmental monitoring with GNSS data.

Real-time and post-processed orbit determination and positioning

Methods and apparatus for autonomous in-receiver prediction of orbit and clock states of Global Navigation Satellite Systems (GNSS) are described. Only the GNSS broadcast message is used, without need for periodic externally-communicated information. Earth orientation information is extracted from the GNSS broadcast ephemeris. With the accurate estimation of the Earth orientation parameters it is possible to propagate the best-fit GNSS orbits forward in time in an inertial reference frame. Using the estimated Earth orientation parameters, the predicted orbits are then transformed into Earth-Centered-Earth-Fixed (ECEF) coordinates to be used to assist the GNSS receiver in the acquision of the signals. GNSS satellite clock states are also extracted from the broadcast ephemeris and a parameterized model of clock behavior is fit to that data. The estimated modeled clocks are then propagated forward in time to enable, together with the predicted orbits, quicker GNSS signal acquision.

Method and apparatus for autonomous, in-receiver prediction of GNSS ephemerides

Techniques for monitoring and controlling yawing of a GPS satellite in an orbit that has an eclipsing portion out of the sunlight based on the orbital conditions of the GPS satellite. In one embodiment, a constant yaw bias is generated in the attitude control system of the GPS satellite to control the yawing of the GPS satellite when it is in the shadow of the earth.

Techniques for monitoring and controlling yaw attitude of a GPS satellite

An improved analyzing system based on GIPSY-OASIS II software package developed at the Jet Propulsion Laboratory for Global Positioning System, general satellite tracking, orbit determination and trajectory studies. New features and functions include yaw compensation, precise satellite positioning by high-rate GPS clocks, enhanced data filtering and smoothing, a new user interface for controlling orientation of a satellite and its components, and no-fiducial approach to global geodesy. The present invention allows a fully automatic operation and delivery of validated daily solutions for orbits, clocks, station locations and others with no human intervention. A 3D GPS orbit accuracy of 15 cm and the daily repeatability of the 3D global geocentric station location in better than 1 cm have been achieved.

Analyzing system for global positioning system and general satellite

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 is output as part of the orbital correction data, thereby allowing single frequency users to estimate ionospheric delay with an accuracy approaching that of dual frequency users.

Robust real-time wide-area differential GPS navigation

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Altadena, CA, United States of America

William I Bertiger