Design of intelligent receiver system for phase-shift laser range finder

This paper presents the design of an intelligent receiver system based on DSP and Avalanche photodiode. A new method of changing the reverse bias voltage based on the real-time measured noise of the system is proposed to avoid the environment influence on the performance of APD and to obtain the optimal operating performance of the whole system. Both the reverse-biased voltage and the automatic gain control loop are adjusted together by DSP, and so the high SNR is achieved and reception light saturation is eliminated. Method of compensating the walk error based on the reflected signal amplitude is used to improve the precision of phase shift measurement. The laser range finder fitted with the newly designed system can get a dynamic range 1: 1500 and a phase-shift measurement resolution better than 0.045 degrees. The measured diatance resolution is 0.125mm when the modulation frequency is 150MHz,.