Patent ID: 7149648

Claim:
A method in a vehicle for determining a position of a reference point relative to the vehicle, the reference point having a transmitter and the vehicle having a plurality of receivers, the transmitter being operatively configured to transmit a first waveform and a second waveform having a relationship with the first waveform, the method comprising: detecting the first waveform by each of the receivers; detecting the second waveform by at least three of the receivers; identifying a first time when the first waveform is detected by a first of the receivers; identifying, for each of the receivers detecting the second waveform, a respective number of cycles of the second waveform detected by the respective receiver between the first time and when the first waveform is detected by the respective receiver; calculating the position of the reference point using a triangulation technique; and maintaining the vehicle relative to the reference point based on the position of the reference point.