Transponder location and tracking system and method
First Claim
1. A vehicle location system for toll collection comprising:
- phased array antenna means mounted at a toll collection station having a plurality of antenna array elements for receiving a signal from a transponder mounted on a vehicle and for providing a plurality of antenna element electrical signals in response thereto;
phase detector means for comparing the phase of said electrical signals to provide a plurality of phase difference signals in response thereto;
angle-of-arrival calculation means for converting the phase difference signals to spatial signals to define the angles-of-arrival of said vehicle transponder signal; and
position calculation means for providing an output signal representative of the location of said vehicle in response to said defined angles-of-arrival.
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Accused Products
Abstract
A transponder location and tracking system having a phased array antenna mounted at a toll collection station includes a plurality of antenna array elements for receiving a signal from a transponder mounted on a vehicle and for providing a plurality of antenna element electrical signals. A plurality of phase detectors are provided for comparing the phase of the electrical signals to provide a plurality of phase difference signals. A plurality of angle-of-arrival calculation processors is provided for converting the phase difference signals to spatial signals to define the angles-of-arrival of the vehicle transponder signal. A position calculation processor is included for providing an output signal representative of the location of the vehicle in response to the defined angles-of-arrival. In a preferred embodiment, the transponder location and tracking system includes a plurality of receiver processing devices for amplifying and filtering the electrical signals from each antenna element. The phase detectors then compare the phase of the electrical signals to a reference element signal. Each phase detector provides a digital representation of the phase difference signals. The spatial signals represent the angle-of-arrival of the vehicle transponder signal. The position calculation processor operates on the spatial signal to determine the vehicle transponder position. A tracking mechanism is provided to plot the location of a moving vehicle along the roadway.
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Citations
18 Claims
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1. A vehicle location system for toll collection comprising:
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phased array antenna means mounted at a toll collection station having a plurality of antenna array elements for receiving a signal from a transponder mounted on a vehicle and for providing a plurality of antenna element electrical signals in response thereto; phase detector means for comparing the phase of said electrical signals to provide a plurality of phase difference signals in response thereto; angle-of-arrival calculation means for converting the phase difference signals to spatial signals to define the angles-of-arrival of said vehicle transponder signal; and position calculation means for providing an output signal representative of the location of said vehicle in response to said defined angles-of-arrival. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A vehicle location and tracking system for toll collection comprising:
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phased array antenna means mounted at a toll collection station having a plurality of antenna array elements for receiving a signal from a transponder mounted on a vehicle and for providing a plurality of antenna element electrical signals in response thereto; phase detector means for comparing the phase of said electrical signals to provide a plurality of phase difference signals in response thereto; angle-of-arrival calculation means for converting the phase difference signals to spatial signals to define the angles-of-arrival of said vehicle transponder signal; position calculation means for providing an output signal representative of the location of said vehicle in response to said defined angles-of-arrival; and means for receiving and storing a plurality of said output signals and for providing a plurality of position parameter values to track the location of said vehicle. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for locating and tracking a vehicle, said method comprising the steps of:
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receiving a signal from a transponder mounted on a vehicle with a plurality of antenna array elements of a phased array antenna mounted at a toll collection station; providing a plurality of antenna element electrical signals with said antenna array elements in response to said vehicle transponder signal; amplifying and filtering said antenna element electrical signals in a receiver processing device; comparing the phase of said amplified and filtered electrical signals to provide a plurality of phase difference signals; converting said phase difference signals to spatial signals to define the angles-of-arrival of said vehicle transponder signal; and providing an output signal representative of the location of said vehicle in response to said defined angles-of-arrival. - View Dependent Claims (16, 17, 18)
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Specification