Patent ID: 6385561
Filing Date: 2002-05-07
Classification: G01M,G01R,H04B,H04L

Abstract:
A method for locating faults in a cable network of multi-conductor electrical cables comprises:establishing a test site where the multiple conductors of a cable in the network can be accessed; delivering an interrogation waveform along a first conductor pair of the cable; said interrogation waveform being of finite duration and pulse-like in form; receiving from the first conductor pair a first composite reflected signal which is a time-distributed collection of individual reflections; sampling the first composite reflected signal at time intervals and storing the samples; delivering the same interrogation waveform along a second conductor pair of the cable; receiving from the second conductor pair a second composite reflected signal which is a time-distributed collection of individual reflections; sampling the second composite reflected signal at time intervals and storing the samples; comparing the first and second composite reflected signals to identify deviations there-between by consecutively comparing amplitudes of sample pairs from the first and second composite reflected signals using a function of an adaptive filter and a comparator, the adaptive filter and comparator being arranged consecutively to adapt the samples of the first composite reflected signal to minimise at the output of the comparator the difference signal between the output of the adaptive filter and the second composite reflected signal; identifying a time interval at which the difference signal exceeds a threshold value; and scaling a time domain position of the identified time interval to represent the distance from the test site to a fault in the conductors.