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

摘要

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.

主权项

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.