Navigation system and method
First Claim
1. A system for determining the position of a user terminal comprising:
- means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and
means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the spatial coordinate data and predicted Doppler data for said signal transmitting means, said receiving means transmitting said aiding signal to said user terminal;
said signal transmitting means also transmitting said signal to said user terminal.
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Accused Products
Abstract
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).
955 Citations
24 Claims
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1. A system for determining the position of a user terminal comprising:
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means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the spatial coordinate data and predicted Doppler data for said signal transmitting means, said receiving means transmitting said aiding signal to said user terminal; said signal transmitting means also transmitting said signal to said user terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for determining the position of a user terminal comprising:
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transmitting a signal containing information indicative of the location of the signal source, almanac data, timing and synchronization data (epoch) and clock correction data; receiving said signal at said user terminal; receiving said signal at a location remote from said signal source which is also remote from said user terminal; converting said signal at said remote location to an aiding signal containing information which identifies said signal source as well as the predicted Doppler data and the spatial coordinate data for said signal source; transmitting said aiding signal to said user terminal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. In a system for determining the position of a user terminal including:
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(1) means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and (2) receiving means at said user terminal for receiving said transmitted signal; the improvement in said system comprising; (1) means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the predicted Doppler data and the spatial coordinate data for said signal transmitting means; and (2) means for transmitting said aiding signal to said user terminal; whereby the complexity of said receiving means may be relaxed. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification