Device included in a distance meter system

摘要

An electronic distance meter which makes a distance measurement by phase comparison between measuring signals modulated on an emitted light beam and on a received light beam reflected from a target is provided with a microphone, an amplifier and an extra modulation circuit, which modulates audible information on the measuring signal of the distance meter. A receiver provided with a detector sensible for the optical wavelength region of the emitted light beam is mounted at a reflecting prism mounted at the target. The receiver at the prism is provided with circuits for detecting the audible information modulated on the measuring signal and a loud speaker or an ear phone. At a receiver of the distance meter the audible information is filtered out from the received measuring signal before distance calculation is made by internal circuits of the instrument.