Noise-domain reflectometry for locating wiring faults

Reflectometry is commonly used to determine the integrity of cables and wiring. This paper describes a new family of reflectometers, the noise-domain reflectometers (NDR), that uses existing data signals on wiring and does not need to generate any signals of their own. There are two types of NDR, type I (where incident and reflected signals are separated) and type II (where they are superimposed). NDR is totally quiet and passive to other signals on the media. Especially for NDR II, detection can be done totally nonintrusively. In this paper, the working principles of NDR are described. Simulation results and examples for location of faults to within 3 inches on wiring up to 180 feet are provided.