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.

This unique trouble-shooting tool is due to the perturbation of the transmission line with a special pseudonoise (pN) ?key-code? sequence of uncorrelated pulses of random polarity and the subsequent CCR measurement of their aggregate response at the test node input for line fault identification and localisation. Based on the distinct spike-like attribute of the PRBS autocorrelation (ACR) function, a ?pre-location? fault measurement relies on the relative time displacement of the device/system conditioned PRBS CCR ?echo? response from the ACR peak. This procedure not only results in the reflection transit time from the fault interface and thus the distance of the fault from the point of stimulus but also fault/load parameter identification. This methodology can be performed online at low amplitude levels for normal uncorrelated signal traffic rejection and to average out the presence of transmission link extraneous noise pickup over several PRBS cycles.

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 apriori, 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.