초록 ▼

A receiver clock bias signal for a spacecraft in motion is is used to obtain a real-time navigation Kalman filter solution of the clock bias and provide a robust autonomous GPS time reference, even when there are less than 4 GPS satellites within the view of the receiver in the spacecraft. The Kalma

A receiver clock bias signal for a spacecraft in motion is is used to obtain a real-time navigation Kalman filter solution of the clock bias and provide a robust autonomous GPS time reference, even when there are less than 4 GPS satellites within the view of the receiver in the spacecraft. The Kalman filter of the spacecraft provides an accurate solution of the clock bias, with less than 4 GPS satellite signals, by means of a system which uses the knowledge of the dynamic motion of the satellite in conjunction with GPS signals for a robust estimation of time. The system provides an accurate GPS time reference by transferring timing information from an atomic reference standard (GPS) to a spacecraft in motion by directly measuring the GPS signal and without depending upon the tracking of multiple GPS satellites or a static receiver. Implementation in current aerospace qualified GPS receivers, e.g., the "GPS TENSOR.TM.", and known orbital dynamics are used to predict receiver position which aids in the transfer of the GPS time.

대표청구항 ▼

[ What is claimed is:] [1.]1. Apparatus for providing an accurate Global Positioning System (GPS) time reference for a spacecraft in space, comprising:receiver means, in said spacecraft, for receiving clock bias signals to determine a time reference;means, in said spacecraft, for producing signals i

[ What is claimed is:] [1.]1. Apparatus for providing an accurate Global Positioning System (GPS) time reference for a spacecraft in space, comprising:receiver means, in said spacecraft, for receiving clock bias signals to determine a time reference;means, in said spacecraft, for producing signals indicative of the dynamic motion of said spacecraft;a real-time navigation Kalman filter means, in said spacecraft, for directly measuring GPS signals from GPS satellite vehicles and transferring timing information in the form of a receiver clock bias signal to said receiver means based on said GPS signals; andmeans, in said receiver means, for using the signals indicative of the dynamic motion of said spacecraft in conjunction with said receiver clock bias signal to produce a time reference estimation for said spacecraft.