METHOD AND DEVICE FOR DETERMINING THE POSITION OF A PISTON OF A PISTON CYLINDER USING MICROWAVES

摘要

A method for detecting the position of a piston of a piston cylinder is provided. A microwave transmit signal is emitted in the direction of the piston and microwaves reflected from the piston are detected. The transmit signal is a modulated signal with a base frequency sinusoidally modulated at a modulation frequency. An evaluation of the phase between transmit signals and receive signals is performed. A phase determination at the baseband and a simultaneous phase determination at at least one sideband are also performed. The phase determination at the baseband is used for fine determination of the piston position and the phase determination at the at least one sideband is used for coarse determination of the piston position. Bandpass filtering on receive signals and evaluation transmit signals is performed with respect to the base frequency or an intermediate frequency. Bandpass filtering is performed with respect to the modulation frequency.