Reasearch On Optic Singnal Processing Technology Of Power/Time Division Multiplexing Regional Optical Fiber Vibration Sensing System

Power/time division multiplexing regional optical fiber vibration sensing system is based on optical fiber vibration sensors as the sensing units, cascaded together by power/time division multiplexing, through the rear end of the optical signal demodulation, analysis and processing, to realized the invasion of judgment, positioning and alarm. Compared with the traditional distributed optical fiber vibration sensing system, it has the advantages of simple structure, easy multiplexing, low cost, low false alarm rate, easy positioning. This paper research the optic signal processing technology of power/time division multiplexing regional optical fiber vibration sensing system.First, the theoretical mode of vibration sensor and its performance is established, which based on the full-fiber Sagnac interferometer. The architecture and the design scheme of power/time division multiplexing regional optical fiber vibration sensing system is proposed, besides, the key components that affect system’s performance are studied, found that the regional pulse amplitude’s imbalance affect system’s performance adversely. Second, power/time division multiplexing regional optical fiber vibration sensing system is developed. To solve the problems such as different gains of pulses, pulse amplitude’s slow fluctuation, a method of gains equalization and stabilizing among different channels implemented by FPGA controlled variable gain amplifier is proposed. Then, the terminal is manufactured, we determine the PI controller parameters, and vertify the gain equalization adjustment by PI arithmetic through joint debugging. Thirdly, discuss and determine the operating parameters of the optical transmission module, test and determine the light receiving circuit module parameters, the system detects the disturbance information. Test and analyze the performance of automatic gain control. Finally, an engineering demonstration system is built in a new and high technology zone of Nanjing, system function is tested and analyzed, the signal’s characteristics of different disturbance action are observed and discussed. The results show that the system can detect the disturbance signals in multiplexed sensing area and warning at the same time, meanwhile, the response time less than Is, percentage of unreported less than 1%, percentage of false alarm less than 5%.