Method and device for determining the distance between a radio beacon and an onboard unit

• US 9,019,151 B2
• Filed: 11/29/2011
• Issued: 04/28/2015
• Est. Priority Date: 12/07/2010
• Status: Expired due to Fees

• Current Assignee: Kapsch TrafficCom AG (Datax Handelsgmbh)
• Original Assignee: Kapsch TrafficCom AG (Datax Handelsgmbh)
• Inventors: Povolny, Robert, Smely, Dieter, Winkler, Josef, Nagy, Oliver, Paier, Alexander
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US13/701,490
• Publication Number:
  US 20130084890A1
• Time in Patent Office: 1,246 Days
• Field of Search: 342/118
• US Class Current: 342/125
• CPC Class Codes: G01S 11/026 using moving transmitters
• CPC Class Codes: G01S 11/10 using Doppler effect
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G08G 1/01 Detecting movement of traffic to be counted or controlled G08G1/07 - G08G1/14 take precedence
• CPC Class Codes: G08G 1/015 with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds

Abstract

System and method for determining the distance between a radio beacon and a vehicle device passing in the radio beacon, in a road toll system. A signal having a known temporal profile is emitted by one of the radio beacon and vehicle device. The signal is captured in the other component during the passing of the device and the temporal profile of the frequency is recorded in relation to the known temporal profile; a modification in the recoded frequency profile exceeding a first threshold value is detected; two distant wave zones in the frequency profile, lying temporally in front of and behind the detected modification are determined, the zones displaying a frequency modification below a second threshold value are searched for; the recorded frequency profile is scaled in such a way that the distant wave zones take the predetermined values; and the distance is determined from the scaled frequency profile.

Claims

1. A method for determining a distance between a radio beacon and an onboard unit passing the radio beacon in a road toll system, wherein at least one of the radio beacon and the onboard unit emits a signal with a known frequency curve over time, the method comprising:

receiving the signal by the other of the radio beacon and the onboard unit during the passing and recording the curve of the frequency of the received signal over time, wherein the recording of the frequency curve is started when the strength of the received signal exceeds a minimum threshold and is ended when the strength of the received signal falls below the minimum threshold;

detecting a change in the recorded frequency curve exceeding a first threshold value;

determining two far regions in the recorded frequency curve lying before and after the detected change in time that show a frequency change below a second threshold value;

scaling the recorded frequency curve in such a manner that the far regions assume predetermined values; and

determining said distance from the scaled frequency curve.

2. The method according to claim 1, wherein said distance is determined from a gradient of the scaled frequency curve in an inflection point thereof.

3. The method according to claim 1, wherein said distance is determined from a frequency value of the scaled frequency curve lying between an inflection point of the scaled frequency curve and a far region.

4. The method according to claim 1, wherein said distance is determined from an integral of the scaled frequency curve over a section lying between an inflection point thereof and a far region.

5. The method according to claim 1, wherein the recording of the frequency curve is performed over a minimum time period.

6. The method according to claim 1, wherein the signal is emitted by the radio beacon and received by the onboard unit, wherein the recording, detecting, seeking, scaling and determining are performed by the onboard unit.

7. The method according to claim 6, wherein sensor comprises a satellite navigation receiver for determining the position of the onboard unit and a list of prestored locations of radio beacons, and wherein an approach to the radio beacon is detected when a specific position of the onboard unit comes into the vicinity of a stored location.

8. The method according to claim 1, wherein the signal is emitted by the onboard unit and received by the radio beacon, wherein the recording, detecting, seeking, scaling and determining are performed by the radio beacon.

9. The method according to claim 8, wherein the sensor is a transceiver for radio interrogation of the onboard unit, the transceiver having a range greater than a receiving range of the radio beacon for said signal.

10. The method according to claim 1, wherein the signal is emitted intermittently and the frequency curve is processed in a time-discrete manner for time points at which the signal is received.

11. The method according to claim 1, wherein a road lane of a multi-lane road in which the onboard unit is moving is determined from the distance.

12. The method according to claim 1, wherein the curve of the frequency of the received signal is normalised to the known frequency curve before detecting said change in the recorded frequency curve.

13. A radio beacon for a road toll system for determining a distance of a vehicle passing the radio beacon, wherein the vehicle is equipped with an onboard unit which emits a signal with a known frequency curve over time comprising:

a receiver configured to receive the signal of said passing vehicle;

a sensor for detecting an approach of said vehicle towards the radio beacon;

a memory electrically coupled to the receiver and the sensor and configured to record the curve of the frequency of the received signal over time, when said sensor detects the approach of the vehicle;

a detector electrically coupled to the memory and configured to detect a change in the recorded frequency curve exceeding a first threshold value;

a first evaluation device electrically coupled to the detector and the memory and configured to determine two far regions in the recorded frequency curve lying before and after the detected change that show a frequency change below a second threshold value;

a scaling device electrically coupled to the memory and the first evaluation device and configured to scale the recorded frequency curve in such a manner that the far regions assume predetermined values; and

a second evaluation device electrically coupled to the scaling device and configured to determine the distance from the scaled frequency curve.

14. The radio beacon according to claim 13, wherein the second evaluation device is further configured to determine said distance from a gradient of the scaled frequency curve in an inflection point thereof.

15. The radio beacon according to claim 13, wherein the second evaluation device is further configured to determine said distance from a frequency value of the scaled frequency curve lying between an inflection point of the scaled frequency curve and a far region.

16. The radio beacon according to claim 13, wherein the second evaluation device is further configured to determine said distance from an integral of the scaled frequency curve over a section lying between an inflection point thereof and the far regions.

17. The radio beacon according to claim 13, further comprising a transmitter for periodically emitting a request signal to prompt passing onboard units to respectively emit a response signal, wherein the radio beacon processes the frequency curve in a time-discrete manner for time points at which the request signal is received.

18. The radio beacon according to claim 13, wherein the sensor comprises a transceiver having a range greater than a range of the receiver for receiving said signal.

19. The radio beacon according to claim 13, wherein the memory is configured to record the curve of the frequency of the received signal over time normalised to the known curve.

20. An onboard unit for a road toll system for determining a distance from a radio beacon of the road toll system, wherein the radio beacon emits a signal with a known frequency curve over time comprising:

a receiver configured to receive the signal from the radio beacon;

a sensor for detecting an approach of the onboard unit towards said radio beacon;

a memory electrically coupled to the receiver and the sensor and configured to record the frequency curve of the received signal over time, when said sensor detects said approach;

a detector electrically coupled to the memory and configured to detect a change in the recorded frequency curve exceeding a first threshold value;

a first evaluation device electrically coupled to the detector and the memory and configured to determine two far regions in the recorded frequency curve lying before and after the detected change in time that show a frequency change below a threshold value;

a scaling device electrically coupled the memory and the first evaluation device and configured to scale the recorded frequency curve in such a manner that the far regions assume predetermined values; and

a second evaluation device electrically coupled to the scaling device and configured to determine the distance from the scaled frequency curve.

21. The onboard unit according to claim 20, wherein the second evaluation device is further configured to determine said distance from a gradient of the scaled frequency curve in an inflection point thereof.

22. The onboard unit according to claim 20, wherein the second evaluation device is further configured to determine said distance from a frequency value of the scaled frequency curve lying between an inflection point of the scaled frequency curve and the far regions.

23. The onboard unit according to claim 20, wherein the second evaluation device is further configured to determine said distance from an integral of the scaled frequency curve over a section lying between an inflection point thereof and the far regions.

24. The onboard unit according to claim 20, wherein the sensor comprises a satellite navigation receiver for determining the position of the onboard unit and a list of prestored locations of radio beacons and is configured to detect the approach to the radio beacon when a specific position of the onboard unit comes into the vicinity of a stored location.

25. The onboard unit according to claim 20, wherein the memory is configured to record the curve of the frequency of the received signal over time normalised to the known curve.

26. A method for determining a distance between a radio beacon and an onboard unit passing the radio beacon in a road toll system, wherein at least one of the radio beacon and the onboard unit emits a signal with a known frequency curve over time, the method comprising:

receiving the signal by the other of the radio beacon and the onboard unit during the passing and recording the curve of the frequency of the received signal over time, wherein the recording of the frequency curve is started when an approach of the onboard unit to a radio beacon is detected by a sensor of the onboard unit;

detecting a change in the recorded frequency curve exceeding a first threshold value;

determining two far regions in the recorded frequency curve lying before and after the detected change in time that show a frequency change below a second threshold value;

scaling the recorded frequency curve in such a manner that the far regions assume predetermined values; and

determining said distance from the scaled frequency curve.

27. The method according to claim 26, wherein the curve of the frequency of the received signal is normalised to the known frequency curve before detecting said change in the recorded frequency curve.

28. The method according to claim 26, wherein said distance is determined from a gradient of the scaled frequency curve in an inflection point thereof.

29. The method according to claim 26, wherein said distance is determined from a frequency value of the scaled frequency curve lying between an inflection point of the scaled frequency curve and a far region.

30. The method according to claim 29, wherein sensor comprises a satellite navigation receiver for determining the position of the onboard unit and a list of prestored locations of radio beacons, and wherein an approach to the radio beacon is detected when a specific position of the onboard unit comes into the vicinity of a stored location.

31. The method according to claim 26, wherein said distance is determined from an integral of the scaled frequency curve over a section lying between an inflection point thereof and a far region.

32. The method according to claim 26, wherein the recording of the frequency curve is performed over a minimum time period.

33. The method according to claim 26, wherein the signal is emitted by the radio beacon and received by the onboard unit, wherein the recording, detecting, seeking, scaling and determining are performed by the onboard unit.

34. The method according to claim 26, wherein the signal is emitted intermittently and the frequency curve is processed in a time-discrete manner for time points at which the signal is received.

35. The method according to claim 26, wherein a road lane of a multi-lane road in which the onboard unit is moving is determined from the distance.

36. A method for determining a distance between a radio beacon and an onboard unit passing the radio beacon in a road toll system, wherein at least one of the radio beacon and the onboard unit emits a signal with a known frequency curve over time, the method comprising:

receiving the signal by the other of the radio beacon and the onboard unit during the passing and recording the curve of the frequency of the received signal over time, wherein the recording of the frequency curve is started when an approach of an onboard unit to the radio beacon is detected by a sensor of the radio beacon;

detecting a change in the recorded frequency curve exceeding a first threshold value;

determining two far regions in the recorded frequency curve lying before and after the detected change in time that show a frequency change below a second threshold value;

scaling the recorded frequency curve in such a manner that the far regions assume predetermined values; and

determining said distance from the scaled frequency curve.

37. The method according to claim 36, wherein the curve of the frequency of the received signal is normalised to the known frequency curve before detecting said change in the recorded frequency curve.

38. The method according to claim 36, wherein said distance is determined from a gradient of the scaled frequency curve in an inflection point thereof.

39. The method according to claim 36, wherein said distance is determined from a frequency value of the scaled frequency curve lying between an inflection point of the scaled frequency curve and a far region.

40. The method according to claim 36, wherein said distance is determined from an integral of the scaled frequency curve over a section lying between an inflection point thereof and a far region.

41. The method according to claim 36, wherein the recording of the frequency curve is performed over a minimum time period.

42. The method according to claim 36, wherein the signal is emitted by the onboard unit and received by the radio beacon, wherein the recording, detecting, seeking, scaling and determining are performed by the radio beacon.

43. The method according to claim 42, wherein the sensor is a transceiver for radio interrogation of the onboard unit, the transceiver having a range greater than a receiving range of the radio beacon for said signal.

44. The method according to claim 36, wherein the signal is emitted intermittently and the frequency curve is processed in a time-discrete manner for time points at which the signal is received.

45. The method according to claim 36, wherein a road lane of a multi-lane road in which the onboard unit is moving is determined from the distance.