Transponder location and tracking system and method

• US 5,227,803 A
• Filed: 07/22/1992
• Issued: 07/13/1993
• Est. Priority Date: 07/22/1992
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: O'Connor, Roger J., Nishida, Michael Y., Shloss, Peter D.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US07/918,734
• Time in Patent Office: 356 Days
• Field of Search: 342/424, 342/442, 342/456, 342/51, 342/156
• US Class Current: 342/442
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G

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.

Claims

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.

2. The vehicle location system of claim 1 wherein said phased array antenna means comprises a plurality of antenna arrays.

3. The vehicle location system of claim 1 wherein said phase detector means comprises a plurality of phase comparators.

4. The vehicle location system of claim 1 wherein said phase detector means comprises a double balance mixer.

5. The vehicle location system of claim 1 wherein said position calculation means comprises a microprocessor.

6. The vehicle location system of claim 1 further including means for amplifying and filtering said antenna element electrical signals.

7. The vehicle location system of claim 6 wherein said amplifying and filtering means comprises a receiver processing device.

8. The vehicle location system of claim 7 wherein said receiver processing device includes a multi-channel superheterodyne receiver.

9. A vehicle location and tracking 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;

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.

10. The vehicle location and tracking system of claim 9 wherein said means for receiving and storing said output signals and for providing said position parameter values includes a microprocessor controlled tracking circuit.

11. The vehicle location and tracking system of claim 9 wherein said position parameter values include the parameters of speed and direction.

12. The vehicle location and tracking system of claim 9 further including a transponder position processing device for utilizing said output signals and said position parameter values to estimate the position of said vehicle.

13. The vehicle location and tracking system of claim 9 further including a sensor device for indicating the present of said vehicle.

14. The vehicle location and tracking system of claim 9 further including an annunciator device.

15. A method for locating and tracking a vehicle, said method comprising the steps of:

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.

16. The method of claim 15 further including the step of receiving and storing a plurality of said output signals and providing a plurality of position parameter values to track the location of said vehicle.

17. The method of claim 15 further including the step of detecting the presence of said vehicle with a sensor device.

18. The method of claim 15 further including the step of estimating the position of said vehicle with a transponder position processing device by utilizing said output signals and said position parameter values.