04445118 is referenced by 626 patents and cites 9 patents.

In a global positioning system (GPS), such as the NAVSTAR/GPS system, wherein the position coordinates of user terminals (14) are obtained by processing multiple signals transmitted by a constellation of orbiting satellites (16), an acquisition-aiding signal generated by an earth-based control station (12) is relayed to user terminals via a geostationary satellite (10) to simplify user equipment. The aiding signal is FSK modulated on a reference channel slightly offset from the standard GPS channel. The aiding signal identifies satellites in view having best geometry and includes Doppler prediction data as well as GPS satellite coordinates and identification data associated with user terminals within an area being served by the control station (12) and relay satellite (10). The aiding signal significantly reduces user equipment by simplifying spread spectrum signal demodulation and reducing data processing functions previously carried out at the user terminals (14).

Title
Navigation system and method
Application Number
6/266253
Publication Number
4445118
Application Date
May 22, 1981
Publication Date
April 24, 1984
Inventor
James W Sennott
Bloomington
IL, US
Ralph E Taylor
Silver Spring
MD, US
Agent
Ronald F Sandler
John R Manning
John O Tresansky
Assignee
The United States of America represented by the Administrator of the National Aeronautics and Space Administration
DC, US
IPC
H04B 7/185
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