Speaker: Zhang Qinghua, Directeur de Recherche, I4S project-team, INRIA, Campus de Beaulieu, 35042 Rennes Cedex, France
Abstract: For the diagnosis of electrical cable failures, reflectometry-based methods analyze the reflected waves after the injection of an incident wave into the tested cable. Currently this technology is mainly applied to the detection of hard faults characterized by important impedance discontinuities, easily recognizable on the reflected waves. This talk is about the detection of soft faults, characterized by weak impedance variations, with no or slight impedance discontinuities. Classical reflectometry-based methods focusing on reflections from discontinuities become ineffective. The difficulties are that, on the one hand, the possible soft faults are of unknown shapes and at unknown positions, on the other hand, reflectometry measurements are made from a single end of the cable. The presented method is based on the telegrapher’s equations, by computing the characteristic impedance distributed along the cable from reflectometry measurements made at one end of the tested cable. The developed hardware and software form a distributed impedance meter based on a single point measurement. The performance of this method is illustrated by experimental results.
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