The Design Of Distributed Optical Fiber Perturbation Monitoring System Based On Virtual Instrument Platform

Security monitoring of the dams, bridges, roads, oil and gas pipelines and other infrastructure has been a basic requirement of social stability and economic development. The traditional low-tech detection methods could only defect evidents after the damage but not to avoid. Thus, it has a major social significance that warning before failure to allow sufficient time to stop the destruction or enhanced prevention by new effective real-time monitoring.Optical fiber sensor is capable of sensing and transmission of the external signal, to light as the carrier and to optical fiber as a medium. Of the characteristics as high sensitivity, light weight, flexible, anti-electromagnetic interference, corrosion resistance, it can be widely used in lots of economic construction and social development fields.With the help of the virtual instrument platform, combined with a distributed optical fiber sensing system characteristics, this paper designed a set of signal acquisition, playback, analysis and alarm monitoring system for distributed optical fiber disturbance software. By the Saigenake photodetector optical fiber interferometer consisted of semiconductor laser light source, optical fiber delay loop, couplers, Faraday rotation mirror, the monitoring system got the disturbance signal, then converted into voltage signal conditioning circuit. The work of the author realized the real-time voltage signal data acquisition and system level analysis and processing.The data acquisition based on MP4210 12-bit high-speed A/D conversion card, and the interactive interface design and data analysis software based on the LabVIEW platform. This paper has accomplished software design and related settings of the sampling mode, sampling channels, sampling rate, range, analog input control; realized the function of time and frequency domain signal display, data storage, data representation; designed customer assistance module as audible alarm, help, password exit.This paper designed three methods to determine the alarm as fast Fourier transform, peak warning, over the threshold sum, and validated test on the platform to compare their advantages and disadvantages. This paper simulated disturbance source, which may occur in the environment, like shaking, mining, touch and drill noise; discussed the signal waveform characteristics in time and frequency domain, validated the intrusion judge effectiveness of the four methods; proved the relationship between the fiber delay loop length and the system sensitivity.Through the study of designing a practical optical fiber distributed disturbance monitoring software, this paper built the foundation of a kind of security monitoring system.