Apparatus and method for autonavigation with one or more orbiting satellites and an anchor station
First Claim
1. A system for carrying out communications between one or more earth-orbiting satellites and a fixed reference point, and for computing the position of said satellites with respect to said reference point, comprising:
- an anchor of fixed position relative to the earth'"'"'s surface having an anchor receiving means for receiving data and autonomous navigation messages transmitted from said satellites, wherein said anchor communicates with at least one of said satellites, said anchor including a time reference clock and including means for computing position determinations for each of said satellites with which communication is established relative to said anchor and for computing a satellite clock time, means for computing a corrected satellite clock value according to said time reference clock, and means for broadcasting said position determinations and said corrected satellite clock value to said satellites, said position determinations being periodically updated;
wherein each of said satellites includes means for receiving said autonomous navigation messages from other of said satellites and means for broadcasting said autonomous navigation messages to said other of said satellites.
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Accused Products
Abstract
A system of making satellite-to-ground range measurements, carrying out communications between a ground station and a constellation of autonavigating satellites, and using these range measurements to improve navigation accuracy is disclosed. The system comprises an anchor that is in a fixed position relative to the earth. The anchor implements a filtering algorithm to arrive at solutions for the satellites'"'"' positions based on measured satellite positions and predicted satellite positions. Each time a new measurement is received by the anchor an update is generated. In this manner the system is capable of updating satellite positions at a greater rate than similar prior art systems, thereby, decreasing the transient response associated with satellite delta-v maneuvers and decreasing the quantity of data that must be exchanged by the anchor and the satellites.
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Citations
23 Claims
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1. A system for carrying out communications between one or more earth-orbiting satellites and a fixed reference point, and for computing the position of said satellites with respect to said reference point, comprising:
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an anchor of fixed position relative to the earth'"'"'s surface having an anchor receiving means for receiving data and autonomous navigation messages transmitted from said satellites, wherein said anchor communicates with at least one of said satellites, said anchor including a time reference clock and including means for computing position determinations for each of said satellites with which communication is established relative to said anchor and for computing a satellite clock time, means for computing a corrected satellite clock value according to said time reference clock, and means for broadcasting said position determinations and said corrected satellite clock value to said satellites, said position determinations being periodically updated; wherein each of said satellites includes means for receiving said autonomous navigation messages from other of said satellites and means for broadcasting said autonomous navigation messages to said other of said satellites. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for carrying out communications between one or more earth-orbiting satellites and a point of fixed position relative to the earth'"'"'s surface, and for computing the position of said satellites with respect to the earth, comprising the steps of:
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providing an anchor of fixed position relative to the earth'"'"'s surface; broadcasting from each of said satellites an autonomous navigation message, each said message containing said satellite'"'"'s determination of its own position; receiving autonomous navigation broadcasts from each of said satellites at said anchor; implementing a tracking algorithm at said anchor for computing a position determination of said orbiting satellites relative to the earth, wherein, said position determination is based on autonomous satellite navigation data and data available independently to said anchor; broadcasting said position determinations to said satellites as part of an autonomous navigation message sent from said anchor; implementing a tracking algorithm at each of said satellites that is substantially similar to the tracking algorithm implemented at said anchor, said tracking algorithm being used at each of said satellites to generate an updated satellite position determination; and broadcasting said updated satellite position determinations for reception by said anchor and said satellites. - View Dependent Claims (9)
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10. A system for carrying out communications between one or more earth-orbiting satellites and a point of fixed position relative to the earth'"'"'s surface, and for computing the position of said satellites with respect to the earth, comprising:
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transmitting means on board each of said satellites for transmitting data to said anchor and for transmitting data to other of said satellites; an anchor having an anchor receiving means for receiving data from said satellites, a first processing means for computing a position determination for each of said satellites, and for computing a satellite clock time, a means for computing a corrected clock value by comparing said satellite clock time to a time reference, and an anchor transmitting means for transmitting said position determination and said corrected clock value to said satellites, said position determination being updated every time a transmission is received from one of said satellites; receiving means on board each of said satellites for receiving transmissions from said anchor and for receiving transmissions from other of said satellites; and means on board each of said satellites for extracting position and time data received from said anchor and from other satellites, and for using said position and time data as input to a second processing means, said second processing means computing an on-board position determination for each of said satellites and for computing an on-board corrected clock value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification