Apparatus for detecting and locating a fault in an electric cable using a pulse-echo technique comprises means for injecting step function or single pulses into a cable, means for digitizing and storing the pulse-echo signal obtained under two different conditions of the cable, and means for retrieving...http://www.google.com/patents/US4475079?utm_source=gb-gplus-sharePatent US4475079 - Apparatus for locating faults in electric cables
