| In interference arm of long distance all-fiber perimeter security system, system architecture had to be complex and expensive in cost on hardware design and signal processing unit, so as to increase the signal to noise ratio and reduce the disturbance caused by environmental temperature change and other undefined influence factors. A new multi-area perimeter security system based on optical fiber Michelson interferometer and pattern recognition technique is proposed and demonstrated. The polarization-insensitive optical fiber Michelson interferometer is used as the vibration sensor for perimeter intrusion detection system (PIDS) which reduce the polarization-induced fading. Strain measurement of fiber bonding on host material is analyzed, and signal coupling model between interference signal and environmental behaviors has been established. Noise suppression, behavior analysis and alarm judgments is realized by using Level Crossing (LC) method and Pattern Recognition (PR) technique which meet the requirements of stability, reliability and practicability of security systems. According to theoretical analysis, power transmission model, loss transmission model and intensity transform model between semiconductor laser and photodiode have been constructed. The experiment results show that the system is able to analyze the original signal with LC method and extract the feature values with response time less than 0.5s. Behavior pattern is generated through neural network training. Rain-induced noise and other environmental noise is eliminated by Dynamic Means Algorithm (DMA). In order to build a standard management method and R&D processes standards, system engineering (SE) has been introduced into Integrated Product Development (IPD) project management which focus on the requirements analysis, functional definitions, physical structure and process review among system life-cycle of concept, design, realization and verification stage. |
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