US 6,618,010 B2 · Passive tracking system and method

Abstract

System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes an antenna array with three antenna elements, which preferably are patch antenna elements spaced apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

Claims55

Dependent claims

A passive system for locating a transmitter, said transmitter having a transmitter frequency, said transmitter producing a transmitter signal, said system comprising:

at least one antenna array having a first antenna element, a second antenna element and a third antenna element, said first antenna element being operable for receiving a first received signal from said transmitter, said second antenna element being operable for receiving a second received signal from said transmitter, and said third antenna being operable for receiving a third signal from said transmitter;
and
electronic circuitry for said antenna array to determine a first phase difference Φ1 and a second phase difference Φ2 between said first received signal, said second received signal, and said third received signal, said electronic circuitry being operable for utilizing said first phase difference and said second phase difference for determining location information using the equations φ = arctan ⁡ ( Φ 2 Φ 1 )
and θ = arcsin ( Φ 1 2 + Φ 2 2 π )
which are related to a vector (sin θ cos Φ, sin θ sin Φ, cos θ) oriented in a direction of said transmitter with respect to said at least one antenna array.

2 more elements

A method for passively detecting the location of a transmitter, said transmitter being operable for transmitting a transmitter signal, said transmitter having a transmitter frequency, said method comprising:

receiving said transmitter signal with a first antenna array comprising a first antenna element that produces a first received signal, a second antenna element that produces a second received signal, and a third antenna element that produces a third received antenna signal;
determining a first phase difference and a second phase difference between said first received signal, said second received signal, and said third received signal;
and
utilizing said first phase difference Φ1 and said second phase difference Φ2 to determine location information using the equations φ = arctan ⁡ ( Φ 2 Φ 1 )
and θ = arcsin ( Φ 1 2 + Φ 2 2 π )
which are related to a first vector (sin θ cos Φ, sin θ sin Φ, cos θ) oriented in a direction of said transmitter with respect to said first antenna array.

3 more elements

A method for a passive system operable for determining location characteristics of a plurality of moveable transmitters, each of said plurality of moveable transmitters producing a transmitter signal, said plurality of moveable transmitters having a transmitter frequency, said system comprising:

providing a plurality of receivers spaced apart wherein each of said plurality of moveable transmitters is receivable by at least one of said plurality of receivers;
providing each receiver with an antenna array having three separate antenna elements;
determining two transmitter signal phase shifts (Φ1 and Φ2) at said three separate antenna elements with respect to a first moveable transmitter and a first receiver;
and
utilizing said two transmitter signal phase shifts to determine information using the equations φ = arctan ⁡ ( Φ 2 Φ 1 )
and θ = arcsin ( Φ 1 2 + Φ 2 2 π )
which are related to a vector (sin θ cos Φ, sin θ sin Φ, cos θ) oriented in a first direction of said first moveable transmitter with respect to said first receiver.

4 more elements

A method for modifying an existing communication system comprising a plurality of moveable transceivers and a plurality of affixed transceivers to provide location information related to said plurality of moveable transceivers, said existing communication system being operable for transmitting a data modulated signal via an electromagnetic wave from said plurality of moveable transceivers to said plurality of affixed transceivers, said electromagnetic wave having a wavelength and a transmitter frequency, said method comprising:

mounting an antenna array at each of said affixed transceivers, each antenna array having three antenna elements spaced apart by an integer times one-half of said wavelength, said three antenna elements being operable for producing a first received data modulated signal, a second received data modulated signal, and a third received data modulated signal in response to said data modulated signal from a first moveable transceiver of said plurality of moveable transceivers;
providing a receiver with each antenna array for receiving said data modulated signal from said first of said plurality of moveable transceivers, said receiver being operable for measuring a first phase difference Φ1 and a second phase difference Φ2 between said first received data modulated signal, said second received data modulated signal, and said third received data modulated signal;
determining information using the equations φ = arctan ⁡ ( Φ 2 Φ 1 )
and θ = arcsin ( Φ 1 2 + Φ 2 2 π )
which are related to a vector (sin θ cos Φ, sin θ sin Φ, cos θ) oriented in a first direction of said first moveable transceiver from said first phase difference and said second phase difference;
and
utilizing said information related to said first direction for determining a first location of said first moveable transceiver.

4 more elements

Dependencies are inferred from the claim text.

Passive tracking system and method

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Passive tracking system and method

Life of this patent

Abstract

Claims55