Using quadrature modulation for precise fault location over wired communication channels

Wire diagnosis has always been a challenge in many fields including transportation and communicating systems, yet becoming also the key for integrity, safety and security. For time-causality reasons, and for the sake of hardware complexity, it has long been assumed that measuring only the real part of signals within a diagnosis system should be enough for fault detection. However, in certain circumstances, electrical singularities remains undetected. This paper recalls that there is more to discover in the imaginary part of the reflected signal than just an argument to estimate the phase delay. The presented method provides several advantages over state-of-the-art techniques and is particularly well suited for implementations in distributed sensor networks. Accordingly, our measurements were performed through the use of an FPGA-based embedded platform with external frequency-modulation circuits and our estimations were proven quite accurate and realistic for multi-carrier signals, allowing the detection of previously undiscovered defects.