Fine positioning of a user terminal in a satellite communication system
First Claim
1. A method for determining the position of a user terminal in a satellite communications system, comprising the steps of:
- repetitively measuring the characteristics of communication signals exchanged between said user terminal and a gateway through one or more satellites, wherein all of the repetitive measurements are accumulated; and
combining the accumulated measurements to produce a position estimate, thereby mitigating the effects of random errors in the measurements.
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Accused Products
Abstract
An improved method for determining the location of a user terminal with a high degree of accuracy. By repeating N times the basic active positioning measurement sets, a much better accuracy is reached that will be of value to the user. According to the method of the present invention, the user makes a position call. A position call prompts a gateway to establish a traffic channel on which a positioning message will yield the basic set of measurements: round-trip delay and round-trip Doppler in single-satellite positioning, and the addition of delay-difference and Doppler difference to a second satellite in two-satellite positioning. The accumulated measurements are used to determine position and theoretical error. The call is terminated when an accuracy threshold is reached or a time limit has expired. The user terminal receives a position message or a failure message.
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Citations
28 Claims
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1. A method for determining the position of a user terminal in a satellite communications system, comprising the steps of:
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repetitively measuring the characteristics of communication signals exchanged between said user terminal and a gateway through one or more satellites, wherein all of the repetitive measurements are accumulated; and
combining the accumulated measurements to produce a position estimate, thereby mitigating the effects of random errors in the measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for determining the position of a user terminal in a satellite communications system, comprising:
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means for repetitively measuring the characteristics of communication signals exchanged between said user terminal and a gateway through one or more satellites, wherein all of the repetitive measurements are accumulated; and
means for combining the accumulated measurements to produce a position estimate, thereby mitigating the effects of random errors in the measurements. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification