Patent ID: 8963770
Filing Date: 2015-02-24
Classification: G01S,G07B,G08G,H04W

Abstract:
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 curve of its frequency 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; 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.