Methods, systems, and articles of manufacture determine the position of a reference point relative to a vehicle. The reference point includes a transmitter operatively configured to transmit a first waveform and a second waveform having a relationship with the first waveform. The vehicle has a plurality of receivers disposed at a plurality of locations relative to the vehicle. The first waveform is detected by each of the receivers. The second waveform is detected by at least three of the receivers, each of which detects a respective number of cycles of the second waveform between the time the first receiver detects the first waveform and when the first waveform is detected by the respective receiver. The reference point position is calculated using a triangulation technique based on each of the identified number of cycles and each location of the receivers detecting the second waveform.