Automated phase offset correction using reflectometry in fault detection systems
Résumé
Well established cable network diagnosis systems rely on reflectometry and transferometry principles to detect faults using specific signals within a frequency spectrum of a few hundreds MHz only. Huge performance improvements in terms of precision and sensitivity can be achieved with higher frequencies and signal modulation, hence revealing phase and amplitude response of the potential impedance discontinuities on the tested channel to better classify the defects. However, as for telecommunications, frequency translation requires a special care in signal processing and integrity, the relative complexity of which has discouraged its implementation in wire diagnosis systems for now. Crossing the domains with an ingenious phase-offset correction mechanism, we show that defects can be accurately detected and correctly analyzed with our system relying on quadrature modulation. 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 using an FPGA-based embedded platform and discrete high-frequency components.