Patent ID: 7046345
Filing Date: 2006-05-16
Classification: G01S

Abstract:
1. An apparatus for precise distance measurement, comprising: a multiple frequency generator that generates a base signal, an interim signal and a transmission signal; a laser transmitter connected to the multiple frequency generator to output a light signal with the transmission signal to a target; an optical receiver that receives the light signal from the laser transmitter reflected by a target and outputs a measurement signal; wherein the optical receiver is connected to the multiple frequency generator and mixes the base signal and the reflected light signal to output a measurement signal; a first measuring unit connected to the multiple frequency generator and the optical receiver obtains a time difference by calculating a time difference between the measurement signal and the transmission signal; a second measuring unit connected between the multiple frequency generator and the optical receiver to calculate a phase difference by comparing the measurement signal and the interim signal, wherein the second measuring unit comprises: a signal corrector connected to the optical receiver to modify the measurement signal's wave form and generate a modified measurement signal, wherein the signal corrector comprises a band-pass filter connected to the optical receiver and a wave form shaper connected to the band-pass filter and the phase comparator; a phase comparator connected to the wave form shaper of the signal corrector and the multiple frequency generator to calculate the phase difference between the interim signal and the modified measurement signal; and a central processing unit connected to the first and second measuring units to calculate a distance between the laser transmitter and a target by the time difference and the phase difference.