Communication system and method for determining the location of a transponder unit
First Claim
1. A remote radio locating and two-way message delivery system for mobile resource management, comprising:
- at least one transponder device which uses a radio frequency communication link;
an array of at least three base stations which communicate with the transponder device using the radio frequency communication link;
wherein the radio frequency communication link employed by each base station and the transponder device includesmeans for generating successive impulse bursts of an intermediate-frequency signal,means for correlating successive impulse bursts with selected ones of a family of modulating sequences based on prescribed PRN codes, so that each resulting correlate represents a particular multi-bit data symbol, and transmitting the resulting correlates,means for receiving the transmitted correlates and decorrelating the received correlates with the same PRN-code-based modulating sequences to produce impulse bursts shifted in time with respect to the originating impulse bursts by the times taken for the transmitted correlates to traverse the distance between the transmitter and receiver,means for identifying a message data symbol corresponding to the PRN code used to decorrelate each received correlate, andmeans for determining the location of the transponder device that transmits a correlate, using the time shift of the impulse burst produced by decorrelating that correlate with respect to the originating impulse burst for that correlate.
3 Assignments
0 Petitions
Accused Products
Abstract
A multilaterating two-way message delivery system for mobile resource management provides efficient two-way radio data communication for multitudes of portable transponders using a single frequency in half-duplex communication. The system includes at least one transponder device which transmits and receives data using a radio frequency communication link, and an array of at least three base stations which communicate with the transponder device using the radio frequency communication link. The radio frequency communication link employed by each base station and the transponder device is designed to provide multilateration information and to deliver message data simultaneously. Further, a control arrangement is coupled to the array of base stations to coordinate the communication between the base stations and the transponder devices. Time-division multiplex and spread spectrum technology is employed by the system for communication efficiency and minimizing the effect of multipath interference.
771 Citations
6 Claims
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1. A remote radio locating and two-way message delivery system for mobile resource management, comprising:
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at least one transponder device which uses a radio frequency communication link; an array of at least three base stations which communicate with the transponder device using the radio frequency communication link; wherein the radio frequency communication link employed by each base station and the transponder device includes means for generating successive impulse bursts of an intermediate-frequency signal, means for correlating successive impulse bursts with selected ones of a family of modulating sequences based on prescribed PRN codes, so that each resulting correlate represents a particular multi-bit data symbol, and transmitting the resulting correlates, means for receiving the transmitted correlates and decorrelating the received correlates with the same PRN-code-based modulating sequences to produce impulse bursts shifted in time with respect to the originating impulse bursts by the times taken for the transmitted correlates to traverse the distance between the transmitter and receiver, means for identifying a message data symbol corresponding to the PRN code used to decorrelate each received correlate, and means for determining the location of the transponder device that transmits a correlate, using the time shift of the impulse burst produced by decorrelating that correlate with respect to the originating impulse burst for that correlate. - View Dependent Claims (2, 3, 4)
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5. A two-way message delivery system for mobile resource management, comprising:
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at least one transponder device which uses a radio frequency communication link; an array of base stations which communicate with the transponder device using the radio frequency communication link; wherein the radio frequency communication link employed by each base station and the transponder device includes means for generating successive impulse bursts of an intermediate-frequency signal, means for correlating successive impulse bursts with selected ones of a family of modulating sequences based on prescribed PRN codes, so that each resulting correlate represents a particular multi-bit data symbol, and transmitting the resulting correlates, means for receiving and decorrelating the transmitted correlates with modulating sequences based on the same prescribed PRN codes used to produce the transmitted correlates, and means for accumulating the signal energy contained in multiple decorrelates resulting from the decorrelation of a correlate received via multiple paths, to improve the data quality.
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6. A remote radio locating and two-way message delivery system for mobile resource management, comprising:
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at least one transponder device which uses a radio frequency communication link; an array of base stations which communicate with the transponder device using the radio frequency communication link; a network control center which controls the array of base stations and which receives the time-of-signal-arrival information from each of the base stations; wherein the radio frequency communication link employed by each base station and the transponder device includes means for generating successive impulse bursts of an intermediate-frequency signal, means for correlating successive impulse bursts with selected ones of a family of modulating sequences based on prescribed PRN codes, so that each resulting correlate represents a particular multi-bit data symbol, and transmitting the resulting correlates, means for receiving and decorrelating the transmitted correlates with modulating sequences based on the same prescribed PRN codes used to produce the transmitted correlates, means for identifying a message data symbol corresponding to the PRN code used to decorrelate each received correlate, and means in said network control center for determining the position of the transmitting transponder devices from the time difference of arrival of said transmitted correlates at their respective base stations and the locations of the respective base stations.
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Specification