A novel pulse echo correlation tool for transmission path testing and fault finding using pseudorandom binary sequences

In this paper, a novel pulse sequence testing methodology is presented as an alternative to time domain reflectometry (TDR) for transmission line 'health' condition monitoring, faultfinding and location. This scheme uses pseudo random binary sequence (PRBS) injection with cross correlation (CCR) techniques to build a unique response profile, as a characteristic signature, to identify the type of fault, if any, or load termination present as well as its distance from the point of stimulus insertion. This fault characterization strategy can be applied to a number of industrial application scenarios embracing high frequency (HF) printed circuit board (PCB) and integrated circuit (IC) device operation, overhead lines and underground cables in inaccessible locations, which rely on a transmission line pathway or 'via' common to all cases either for signal propagation or power conveyance. In this paper a lumped parameter circuit model is presented to emulate generalized transmission line behaviour, using the well-known pSpice simulation package, for a range of known load-terminations mimicking fault conditions in a range of application scenarios encountered in practice. Numerous line behavioural simulations for various fault conditions, known a priori, with measured CCR response demonstrate the capability of and establishes confidence in the effectiveness of the PRBS test method in fault type identification and location. The accuracy of the method is further validated through theoretical calculation using known lumped parameters, fault termination conditions and link distance in transmission line simulation.