Patent ID: 6052190
Filing Date: 2000-04-18
Classification: G01S

Abstract:
Apparatus for measuring distance to a target, the apparatus comprising:an adjustable frequency generator for generating a modulation frequency;a light source connected to said frequency generator for transmitting a transmitted beam of light to the target at said modulation frequency;a target sensor for receiving a reflected beam reflected from the target, said reflected beam having a reflected frequency;a phase detector connected to said frequency generator and said target sensor for receiving said modulation frequency and said reflected frequency and for providing an output indicative of a phase angle between said modulation frequency and said reflected frequency; anda computer connected to said phase detector and said frequency generator, said computer for adjusting said modulation frequency to a first frequency that produces a zero phase difference between said modulation frequency and said reflected frequency, for adjusting said modulation frequency to a second frequency that produces a pre-determined non-zero phase difference between said modulation frequency and said reflected frequency, and for calculating said distance to said target from said first and second frequencies.