Patent ID: 6122043
Filing Date: 2000-09-19
Classification: G01M

Abstract:
In an optical time domain reflectometer for performing measurements on an optical fiber transmission line, in combination:a laser for generating optical pulses for application to said transmission line;a fiberoptic path for transmitting optical pulses generated by said laser to said transmission line;a photodetector for detecting light reflected from said transmission line as optical pulses propagate along said transmission line;coupling means for bi-directionally coupling said photodetector to said fiberoptic path;control means for altering the optical characteristics of said optical pulses to prevent light reflected back toward said reflectometer during the propagation of a plurality of said pulses along said transmission line from being reflected back in substantially the same way during different ones of said optical pulses; andaveraging means for averaging the intensity of the light detected by said photodetector during the propagation of said plurality of different optical pulses;whereby the coherence noise observed on said transmission line is reduced.