US 6,861,982 B2 · System for determining position of an emitter

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.

Claims95

Dependent claims

A method of determining the position or 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, wherein at least one of the receiver communication devices is a mobile communication device;
(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 based on a round-trip signal propagation time determined from exchanging time synchronization signals between the receiver communication devices and the 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.

2 more elements

A mobile communication device for determining a detection time of an emitted signal from an emitter, comprising:

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 based on a round-trip signal propagation time determined from exchanging the outbound and reply time synchronization signals between the mobile communication device and 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.

3 more elements

A system for determining the position of an emitter, comprising:

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, 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 based on a round-trip signal propagation time, 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, wherein at least one of the receiver communication devices is a mobile communication device;
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.

1 more element

Dependencies are inferred from the claim text.

System for determining position of an emitter

Life of this patent

System for determining position of an emitter

Life of this patent

Abstract

Claims95