VEHICLE LOCATION SYSTEM AND METHOD

• US 3,697,941 A
• Filed: 07/01/1971
• Issued: 10/10/1972
• Est. Priority Date: 07/01/1971
• Status: Expired due to Term

• Current Assignee: David L. Christ
• Original Assignee: David L. Christ
• Inventors: Christ, David L.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Myers, Randall P.
• Application Number:
  US05/158,748
• Time in Patent Office: 467 Days
• Field of Search: 340/22,23,24,31R,32,33 250/199 343/6.8R,1CS,112PT,112TC 325/16
• US Class Current: 340/991
• CPC Class Codes: G08G 1/20 Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles

Abstract

Traffic lights in a prescribed area are modulated so that the energy, e.g., visible light, emitted by each light carries a predetermined code different from the modulating code of every other traffic light. Vehicles moving about the prescribed area carry means for sensing the modulated energy emitted by each traffic light, and for transmitting to a remote location a signal incorporating the modulation code. At the remote location, the signal is received and converted into a visual display indicating the location corresponding to the received code.

Claims

1. A vehicle location system for identifying the location of a vehicle moving about a prescribed area in which traffic lights are present, comprising:

a. means associated with individual traffic lights for modulating energy emitted by said lights, the energy emitted by each light being modulated according to a predetermined code different from the modulating code of every other modulated traffic light, each said code identifying the location of its respective traffic light, b. means carried by the vehicle for individually sensing the modulated energy emitted by each traffic light and in response thereto transmitting a signal incorporating a code corresponding to the code carried by the sensed modulated energy, and c. means at a location remote from the vehicle for receiving said signal and in response thereto displaying unique location information corresponding to the code incorporated in said received signal.

2. A vehicle location system as defined in claim 1 wherein said means (a) varies the intensity of energy emitted by each modulated traffic light, said intensity variations being in accordance with said predetermined code identifying the location of that traffic light.

3. A vehicle location system as defined in claim 1 wherein said means (a) modulates said energy so that said code is continually repeated.

4. A vehicle location system as defined in claim 1 including additional means for modulating said traffic-light-emitted energy according to a code which identifies the direction in which its respective traffic light is facing.

5. A vehicle location system as defined in claim 1 wherein said means (a) including means for modulating the flow of electric power to each of the modulated traffic lights so as to modulate the energy emitted by said lights.

6. A vehicle location system as defined in claim 1 wherein said means (a) includes a switch for controlling the flow of electric power to each of the modulated traffic lights, and means including a memory for controlling the operation of said switch in accordance with a binary code identifying the location of that traffic lIght.

7. A vehicle location system as defined in claim 6 wherein said memory operates in synchronism with the A.C. power supplying the traffic light so that the bits of said binary code are generated in synchronism with the frequency of the power supply, and said switch is operated to cut power to the traffic light in accordance with a pattern synchronized with the frequency of the power supplying the traffic light.

8. A vehicle location system as defined in claim 1 wherein said means (a) includes rectifier means for converting the A.C. power supplying the traffic light to D.C., and means for modulating the flow of D.C. power to the traffic light.

9. A vehicle location system as defined in claim 1 wherein the modulated energy emitted by the traffic lights is visible light, and said means (b) includes a light-sensitive device for sensing the light.

10. A vehicle location system as defined in claim 1 wherein said means (b) includes means for converting the modulated energy emitted by a traffic light into an electrical signal carrying the modulating code, storage means for receiving said electrical signal and storing said code and upon request producing an electrical signal carrying said code, and transmitter means for receiving said electrical signal from said storage means and transmitting a signal carrying said code.

11. A vehicle location system as defined in claim 10 wherein said transmitter means is a radio transmitter.

12. A vehicle location system as defined in claim 10 including clock means for automatically initiating, at predetermined intervals, transmission of a signal by said transmitter means carrying the code stored in said storage means at each of said intervals.

13. A vehicle location system as defined in claim 12 in which a plurality of vehicles move about the prescribed area, each of said vehicles carrying said means (b), and wherein said clocks of the vehicles are adjusted so that the transmitter means of each vehicle transmits its coded signal at time different from the time during which said transmitter means of any other vehicle transmits its coded signal.

14. A vehicle location system as defined in claim 10 including means responsive to a polling signal from said remote location for initiating transmission of a signal by said transmitter means carrying the code stored in said storage means at the time said polling signal is received.

15. A vehicle location system as defined in claim 1 wherein said means (b) includes means for incorporating in said transmitted signal additional coded information other than the modulating code.

16. A vehicle location system as defined in claim 15 in which a plurality of vehicles move about the prescribed area, and wherein said additional coded information identifies the vehicle from which said signal is transmitted, said additional code being different for each vehicle.

17. A vehicle location system as defined in claim 1 wherein said means (c) includes receiver means for producing an electrical signal carrying the code incorporated in the signal received from said means (b), storage means for receiving said electrical signal and storing said code and producing an electrical signal carrying said code, and display means for receiving said electrical signal from said storage means and visually displaying information corresponding to said code.

18. A vehicle location system as defined in claim 17 wherein the electrical signal from said receiver means carries said code in signal portions differing from each other in some characteristic, and including filter means between said receiver means and said storage means for separating said differing signal portions and separately presenting them to said storage means.

19. A vehicle location system as defined in claim 17 wherein said receiver means is a radio receiver, and including filter means for separating voice information received by said receiver from the radio signal portion carrying said modulating code.

20. A vehicle location system For identifying the location of a vehicle moving about a prescribed area in which light sources are present, the light sources having a primary function apart from that of vehicle location, said system comprising:

a. means associated with individual light sources for modulating the visible light emitted by said sources, the light emitted by each source being modulated according to a predetermined code different from the modulating code of every other modulated light source, each said code identifying the location of its respective light source, b. means carried by the vehicle for individually sensing the modulated light emitted by each light source and in response thereto transmitting a signal incorporating a code corresponding to the code carried by the sensed modulated light, and c. means at a location remote from the vehicle for receiving said signal and in response thereto displaying unique location information corresponding to the code incorporated in said received signal.

21. A vehicle location system as defined in claim 20 wherein said modulation is undetectable by the human eye.

22. A method of locating a vehicle moving about a prescribed area in which traffic lights are present, comprising:

a. modulating energy emitted by individual traffic lights, the energy emitted by each light being modulated according to a predetermined code different from the modulating code of every other modulated traffic light, each said code identifying the location of its respective traffic light, b. individually sensing at the vehicle the modulated energy emitted by each traffic light and in response thereto transmitting a signal incorporating a code corresponding to the code carried by the sensed modulated energy, and c. receiving said signal at a location remote from the vehicle and in response thereto displaying unique location information corresponding to the code incorporated in said received signal.