Method and apparatus for maintaining integrity of long-term orbits in a remote receiver

Abstract

A method and apparatus for maintaining integrity of long-term-orbit information used by a Global-Navigation-Satellite-System or other positioning receiver is described. The method comprises obtaining a predicted pseudorange from a first set of long-term-orbit information possessed by a positioning receiver; obtaining, at the positioning receiver from at least one satellite, a measured pseudorange; determining validity of the predicted pseudorange as a function of the predicted pseudorange and the measured pseudorange; and excluding from the long-term-orbit information at least a portion thereof when the validity of the predicted pseudorange is deemed invalid. Optionally, the method may comprise updating or otherwise supplementing the long-term-orbit information with other orbit information if the validity of the predicted pseudorange is deemed invalid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part application of co-pending U.S. patent application Ser. No. 11 / 333,787, filed Jan. 17, 2006 (Attorney Docket GLBL 022P2), which is a continuation-in-part application of co-pending U.S. patent application Ser. No. 09 / 993,335, filed Nov. 6, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 884,874, filed Jun. 19, 2001, now U.S. Pat. No. 6,560,534, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 875,809, filed Jun. 6, 2001, now U.S. Pat. No. 6,542,820. [0002] This application is also a continuation-in-part application of co-pending U.S. patent application Ser. No. 11 / 289,959, filed Nov. 30, 2005, which is a continuation of U.S. patent application Ser. No. 10 / 712,807, filed 13 Nov. 2003, now U.S. Pat. No. 6,992,617. [0003] This application contains subject matter that is related to U.S. patent application Ser. No. 09 / 715,860, filed Nov. 17, 2000, now...

AI Technical Summary

Benefits of technology

[0020] A method and apparatus for maintaining integrity of long-term-orbit information used by a GNSS or other positioning receiver is described. The method may include obtaining a predicted pseudorange from a first set of long-term-orbit information possessed by a positioning receiver; obtaining, at the positioning receiver from at least one satellite, a measured pseudorange; determining validity of the predicted pse

Problems solved by technology

Errors in absolute may result in range errors of up to 0.8 m for each millisecond of timing error.

These range errors produce a similarly sized error in the GPS receiver position.

Hence, absolute time accuracy of 10 ms is sufficient for position accuracy of approximately 10 m. Errors in the absolute timing of much more than 10 ms result in large position errors, and so, current and prior implementations have typically required the absolute time to have a minimum accuracy of approximately 10 milliseconds.

When in environments in which the GPS signals have very low signal strengths, downloading the broadcast ephemeris is frequently difficult and sometimes impossible.

Images