Otis Elevator Company

Lutz Vietze

Axel Steffen Gerwing

Claudia M Schmidt-Milkau

A microphone 13 is provided upon the ceiling 4 of an elevator hoistway 3 and a loudspeaker 8 upon the top of an elevator car 1. A 9-16 kHz up-sweep is provided to the loudspeaker 8 and a sound signal is transmitted from the loudspeaker 8 to the microphone 13. The travel time of the sound signal is obtained by cross-correlating 53 the sound signal received by the microphone 13 with a reference signal. The reference signal is a received signal in a relatively noiseless environment. By multiplying the travel time of the signal by its velocity, the distance between microphone and loudspeaker is calculated 59. The hoistway temperature is measured 26 and used 57 in the absolute position calculation 59.

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Berlin, Germany

Lutz Vietze