US 5,353,110 A · Method and apparatus for carrying out optical time domain reflectometry using weighing techniques

Abstract

An optical time domain reflectometry method and apparatus that employs Hadamard transforms to increase the signal-to-noise ratio. A sequence of N pulses of light corresponding to a Hadamard derived code are launched down a fiber optic cable for each of N such codes. Selected combinations of pulses of reflected light are transformed by a Hadamard derived matrix to a set of equations that are solved simultaneously to determine the power reflected from each of N points. Where a Hadamard code is used the average mean square error is reduced by a factor of 1/N. Where a simplex code is employed the average mean square error is reduced by a factor of 4N/(1+N).sup.2. In addition, N measurements of the power reflected at each point are computed and averaged.

Claims33

Dependent claims

A method of carrying out a measurement of the power of energy of a selected form reflected within a medium in which that energy propagates, comprising:

(a) applying energy in selected form to the medium, the power at which energy is applied varying as function of time in accordance with a predetermined number N of sequential element codes, each code having N elements;
(b) receiving energy in said selected form reflected from within said medium;
(c) for each code, measuring the power of said energy reflected from within said medium as a function of time and assigning said power measurements as the sum of the powers reflected from a selected set of points within said medium, the number of points being equal to N;
and
(d) computing the powers reflected at said N points within said medium by solving N equations simultaneously, where each equation represents one said sum of the powers reflected from said selected set of points within said medium.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for carrying out optical time domain reflectometry using weighing techniques

Life of this patent

Method and apparatus for carrying out optical time domain reflectometry using weighing techniques

Life of this patent

Abstract

Claims33