System for determining position of an emitter
First Claim
1. A method of determining the position of an emitter, comprising:
- (a) detecting an emitted signal from the emitter at plural receiver communication devices positioned at different locations, the receiver communication devices determining respective detection times of the emitted signal in respective local time reference frames;
(b) determining respective timing differences between the respective local time reference frames of the receiver communication devices and a time reference frame of a reference communication device;
(c) accounting for the respective timing differences between the respective local time reference frames and the time reference frame of the reference communication device such that the respective detection times are determined in a common time reference frame; and
(d) determining a position of the emitter from known positions of the receiver communication devices and the respective detection times of the emitted signal.
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Accused Products
Abstract
The position of a non-cooperating emitter is determined by detecting a signal from the emitter at three or more receiver communication devices positioned at different locations. The receiver communication devices determine respective detection times of the emitted signal in respective local time reference frames. To establish a common time reference frame for the emitted signal detections, each receiver communication device exchanges time synchronization signals with a reference communication device. Since any of the receiver communication devices and the reference communication device may be mobile, the signal exchange allows each receiver communication device to accurately determine the signal propagation time between itself and the reference communication device and factor the signal propagation time into an accurate adjustment of the local time reference frame. Using trilateration, the position of the emitter is determined from known positions of the receiver communication devices and the emitted signal detection times from the receiver communication devices.
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Citations
102 Claims
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1. A method of determining the position of an emitter, comprising:
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(a) detecting an emitted signal from the emitter at plural receiver communication devices positioned at different locations, the receiver communication devices determining respective detection times of the emitted signal in respective local time reference frames;
(b) determining respective timing differences between the respective local time reference frames of the receiver communication devices and a time reference frame of a reference communication device;
(c) accounting for the respective timing differences between the respective local time reference frames and the time reference frame of the reference communication device such that the respective detection times are determined in a common time reference frame; and
(d) determining a position of the emitter from known positions of the receiver communication devices and the respective detection times of the emitted signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A communication device for determining a detection time of an emitted signal from an emitter, comprising:
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a receiver device configured to detect the emitted signal, the detection time of the emitted signal being determined in a local time reference frame;
a transmitter configured to transmit an outbound time synchronization signal to a reference communication device, said receiver device being configured to receive a reply time synchronization signal from the reference communication device, the reply time synchronization signal indicating a time of arrival of the outbound time synchronization signal at the reference communication device in a time reference frame of the reference communication device; and
a processor configured to;
determine a timing difference between the local time reference frame and the time reference frame of the reference communication device; and
account for the timing difference such that the detection time of the emitted signal is determined in the time reference frame of the reference communication device. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. A communication device for determining a detection time of an emitted signal from an emitter, comprising:
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first receiver means for detecting the emitted signal, the detection time of the emitted signal being determined in a local time reference frame;
means for transmitting an outbound time synchronization signal to a reference communication device;
second receiver means for receiving a reply time synchronization signal from the reference communication device, the reply time synchronization signal indicating a time of arrival of the outbound time synchronization signal at the reference communication device in a time reference frame of the reference communication device;
means for determining a timing difference between the local time reference frame and the time reference frame of the reference communication device; and
means for accounting for the timing difference such that the detection time of the emitted signal is determined in the time reference frame of the reference communication device. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. A reference communication device for establishing a common time reference frame among a plurality of receiver communication devices, comprising:
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a receiver configured to receive outbound time synchronization signals transmitted by respective ones of said receiver communication devices, said reference communication device determining a time of arrival of the outbound time synchronization signals in the common time reference frame;
a transmitter configured to transmit reply time synchronization signals to said respective ones of said receiver communication devices, the reply time synchronization signals indicating the time of arrival of the respective outbound time synchronization signals at the reference communication device in the common time reference frame, thereby enabling said respective ones of the receiver communication devices to synchronize with the common time reference frame based on respective timing differences determined from the time of arrival of the respective outbound time synchronization signal at the reference communication device. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71, 73, 74, 75)
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72. A reference communication device for establishing a common time reference frame among a plurality of receiver communication devices, comprising:
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means for receiving outbound time synchronization signals transmitted by respective ones of said receiver communication devices, said reference communication device determining a time of arrival of the outbound time synchronization signals in the common time reference frame;
means for transmitting reply time synchronization signals to said respective ones of said receiver communication devices, the reply time synchronization signals indicating the time of arrival of the respective outbound time synchronization signals at the reference communication device in the common time reference frame, thereby enabling said respective ones of the receiver communication devices to synchronize with the common time reference frame based on respective timing differences determined from the time of arrival of the respective outbound time synchronization signal at the reference communication device.
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76. A system for determining the position of an emitter, comprising:
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a reference communication device maintaining a time reference frame;
a plurality of receiver communication devices positioned at different locations and configured to detect an emitted signal from the emitter, the receiver communication devices determining respective detection times of the emitted signal in respective local time reference frames, said receiver communication devices exchanging time synchronization signals with said reference communication device to determine respective timing differences between the respective local time reference frames and the time reference frame of said reference communication device and accounting for the respective timing differences such that the respective detection times of the emitted signal at the receiver communication devices are in a common time reference frame; and
a processor configured to receive signal detection information from the receiver communication devices, including the respective detection times, said processor correlating the signal detection information from at least three of the receiver communication devices to a common emitted signal and determining a position of the emitter from known positions of the receiver communication devices and the respective detection times of the common emitted signal. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101)
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102. A system for determining the position of an emitter, comprising:
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means for detecting an emitted signal from the emitter at plural known locations, said means for detecting determining respective detection times of the emitted signal at the plural known locations in respective local time reference frames;
means for determining respective timing differences between the respective local time reference frames and a common time reference frame;
means for accounting for the respective timing differences between the respective local time reference frames and the common time reference frame such that the respective detection times are determined in the common time reference frame; and
means for determining a position of the emitter from the plural known locations and the respective detection times of the emitted signal.
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Specification