Submarine cable monitoring system based on enhanced COTDR with simultaneous loss measurement and vibration monitoring ability.

A submarine cable monitoring system based on enhanced coherent optical time-domain reflectometry (E-COTDR) is realized. An improved optimal peak-seeking (OPS) based I/Q demodulation method is employed for simultaneous loss measurement and vibration monitoring. A single-end diagnosis range over 74km is achieved for the proposed E-COTDR, enabling the double-end cooperative system to have a single-span of 148km. For the multi-span cascaded cables over 1000km, the loss and vibration monitoring without fading zone is carried out for a single-span of 121km. The proposed system provides a reliable technical option for the next generation underwater cable monitoring applications.