Faults In Wiring Networks Research Articles

Multifrequency TR-MUSIC Processing to Locate Soft Faults in Cables Subject to Noise

Time-reversal multiple signal classification (TR-MUSIC) has recently been shown to be an effective technique to locate multiple soft faults in wire networks, thanks to its sub-millimeter location accuracy. TR-MUSIC processes transmission and reflection data measured at a single frequency into a function of space, the pseudo spectrum, expected to present singularities only at a fault position. At frequencies high enough, the spatial periodicity that comes with the propagation of harmonic signals leads to multiples of such singularities, of which only one represents the fault position, while the remaining are ghosts faults. TR-MUSIC was therefore introduced using a single continuous-wave excitation at frequencies low enough to avoid ghosts, an approach suitable only for noiseless configurations. This paper explores the effects of noise on TR-MUSIC fault location by first highlighting its high sensitivity to noise at low frequency. A potentially lower sensitivity is shown to exist at high frequencies, where ghosts positions are found. A multifrequency processing is introduced, allowing at the same time to solve the ambiguity in the fault position and to effectively control the impact of noise on its location accuracy. The proposed processing is shown to reinstate precise super-resolved estimates of fault locations even for signal-to-noise ratios as low as 5 dB, without requiring the use of wideband signals.

Locating Multiple Soft Faults in Wire Networks Using an Alternative DORT Implementation

Decomposition of the time reversal operator (DORT) was recently applied to the problem of detection and location of soft faults in wire networks and proved effectual when dealing with a single fault, even in the case of complex network configurations. In this paper, the case of location of multiple faults is addressed, first proving that the standard DORT formulation does not allow one to take a clear decision about the individual position of each fault. An alternative version of the DORT based on an updating procedure is presented and demonstrated to enable accurate and selective location of multiple soft faults. The proposed procedure is also shown to allow estimating the reflection coefficient of each fault, thus giving access to their severity.