Arrhythmic pulse sequence for sonic distance measurement

摘要

A position detecting device for detecting the position of an object (12) movable along a predetermined path of movement, comprising a signal transmission medium (13) extending along the path of movement, a signal generator (15) movable together with said movable object (12), by means of which a signal can be coupled into the signal transmission medium (13), at least one signal receiver (29, 33) at an extraction location in an end portion of said path of movement, a signal propagation time measuring means (35, 37) adapted to determine the signal propagation time between coupling location and extraction location (45), wherein the signal generator (15) is designed to deliver a periodically repeating signal pulse sequence (FIG. 2) in which the time intervals between consecutive signal pulses are different for each pair of consecutive signal pulses each, the period duration of the repetitive signal pulse sequence is greater than the maximum signal propagation time with maximum interval between coupling location and extraction location, and the time intervals between consecutive signal pulses are shorter than the maximum signal propagation time.