Research on signal processing technology in φ-OTDR system based on non-uniform sampling

Abstract

In the optical cable communication system, because the optical cable often has a long span, the sampling frequency is limited when φ-OTDR is used as the monitoring method. When the system adopts the traditional uniform sampling method, the sampling frequency must be greater than 2 times of the signal frequency, otherwise spectrum aliasing will occur. How to get the frequency information of high frequency signal with lower sampling frequency, and how to solve the problem that the highest response frequency of the system decreases when the sensing distance of φ-OTDR system is extended, is a major technical problem for the monitoring of optical cable communication system. In this paper, through the analysis of the common methods of broadening the response frequency band of Φ-OTDR system, a non-uniform sampling method is selected to analyze the optimal value of some parameters of Φ-OTDR system based on non-uniform sampling, and a method of using the mean square change value to locate the vibration source is proposed. The simulation results show that this method is suitable for monitoring vibration signals with sparse characteristics in frequency domain, and the location SNR is better than the traditional method, and has good anti noise performance.