Abstract: Methods and apparatus for determining the location of a fault or another region of interest in an electrical conductor such as an electrical cable. A preselected electrical signal is applied to the electrical conductor and a reflected signal produced thereby is generated. The reflected signal is compared to a plurality of preselected voltage values and time values are recorded representing times at which the voltage of the reflected signal crosses the preselected voltage values. Mathematical algorithms are applied using the recorded time and voltage values first to locate a suspected knee region in the reflected signal, then to confirm the presence of the knee within the suspected knee region. The location of the knee in the reflected signal is then used to calculate the distance to the fault or other region of interest. A further series of time values is recorded within the suspected knee region and used to more precisely determine the true location of the knee in the reflected signal.

Abstract: A detector and a variable signal generator are coupled so that one or more specific changes in the output of the detector will cause a change in the characteristics of the generated signal. This change in signal characteristics is non-transient, the change remaining in effect until such time that another change in the detector output causes another change in the signal characteristic. The system can provide remote-end positive wire identification with no additional instrumentation at the remote end. When this invention is embodied in an already existing piece of test equipment, such as a multimeter or time domain reflectometer, there need be no additional hardware instrumentation at either end.

Abstract: A detector and a variable signal generator are coupled so that one or more specific changes in the output of the detector will cause a change in the characteristics of the generated signal. This change in signal characteristics is non-transient, the change remaining in effect until such time that another change in the detector output causes another change in the signal characteristic. The system can provide remote-end positive wire identification with no additional instrumentation at the remote end. When this invention is embodied in an already existing piece of test equipment, such as a multimeter or time domain reflectometer, there need be no additional hardware instrumentation at either end.