Positioning Method for Dual Mach-Zehnder Interferometric Submarine Cable Security System

Dual Mach-Zehnder interferometric fiber sensor is one of the appropriate solutions to the application of submarine cable security. While the seabed environment makes the vibration output a narrow bandwidth lowpass interference signal and these property makes the correlation based event positioning algorithm hard to design. A preprocessing method intends to increase signal power spectral range before correlation is proposed. A bandpass filter is imposed to enhance the effect of high frequency components, despite the filtered signal is different from the original one. A post-integration SNR threshold is calculated to determine the proper center frequency and bandwidth of the filter. Experiment results show a good accordance with theoretical prediction.