On-line diagnosis using Orthogonal Multi-Tone Time Domain Reflectometry in a lossy cable

Currently, on-line wire diagnosis using reflectometry is under intensive investigation, aiming at detecting and locating faults on wiring networks while the target system is operating. The idea is to inject a broadband test signal in the network under test and analyse the signal reflected by each impedance discontinuity. However, the presence of native signals on live wires may impact the diagnosis due to interference and EMC or limited bandwidth constraints. Our proposed "Orthogonal MultiTone Time Domain Reflectometry"(OMTDR) method, based on Orthogonal Frequency Division Multiplexing (OFDM) technique, seems to be a suitable candidate for on-line diagnosis as it achieves high data rate transmission, interference robustness, bandwidth efficiency and complete spectrum control. Moreover, it allows communication among diagnosis sensors to accurately locate faults position in multi-branch wiring networks which require more than one diagnosis sensor.