Analog and digital implementation of an accurate phasemeter for laser range finding

A high precision phasemeter is developed for a phase-shift laser range-finding application. The specifications are high precision (about 0.01°), transportability and compatibility with spatial environment. Two techniques are implemented, one based on an analog circuit and the other on a digital treatment, and the performances obtained are compared. The first technique is based on an analog balanced modulator, working in its saturated mode. The second technique uses early digital conversion, associated with a software sinus reconstitution.