Design Of Human-Computer Interaction Software For Distributed Optical Fiber Sensors

Fiber optic sensing technology has many advantages,such as anti-electromagnetic interference,anti-corrosion and long-distance transmission.It has been widely used in national defense,military,industry,transportation,medicine,education,family and other fields.Based on Brillouin scattering light time domain reflection principle,an optical fiber sensing system has been developed in our laboratory.The system can measure the physical information such as temperature or strain.However,when applying optical fiber sensing technology to data acquisition,monitoring and transmission in various fields,corresponding software systems are needed to achieve interactive control.Based on Python(x,y)as the main development platform,a distributed optical fiber sensor human-computer interaction software platform is designed and developed to serve the distributed optical fiber sensor system.The human-computer interaction software designed in this paper mainly realizes the setting of acquisition parameters and data acquisition of the optical fiber sensor system.After processing and calculating the original data collected,the temperature and strain information on the optical fiber can be obtained,and the results obtained(original data,temperature change,strain change)can be displayed through the interactive interface.This paper designs the modules for the setting of acquisition parameters and the control of data acquisition.The data processing module is also designed for the calculation and processing of the collected data and the database module is developed for the storage and query of the collected data.The graphics processing operations such as saving,enlarging,reducing,setting the coordinate axis range and three-dimensional image observation angle of the interface display are the functions of the image processing module.Brillouin Optical Time Domain Reflectometer(BOTDR)based on spontaneous Brillouin scattering can detect temperature or strain,but the sensing distance is limited by the inherent attenuation of optical fibers.To overcome this shortcoming,Brillouin Time Domain Analysis(BOTDA)based on stimulated Brillouin scattering(SBS)can enhance the efficiency of Brillouin scattering and realize long-distance transmission by introducing a continuous probe light with reverse transmission,which acts as a stimulated Brillouin interaction with the forward transmission pulse.In order to increase the sensing distance,the method of increasing the power of incident light can be used.However,because of the nonlinear effect of optical fibers,the upper limit of the power is generally no more than 5 dBm.FSK modulation technology can improve the detection optical power and increase the Brillouin threshold as much as possible,however,the relationship between FSK signal and threshold has not been studied.Therefore,based on the coupling equation in optical fibers,a spontaneous Brillouin scattering threshold estimation model based on n-FSK modulation is proposed.The relationship between threshold and the period,number of tone and sweep range of n-FSK modulated signal is deeply studied.The Brillouin thresholds of different n-FSK modulated signals can be calculated according to the threshold estimation.When the modulated signals are 2-FSK,10-FSK and 40-FSK,the spontaneous Brillouin scattering threshold can reach 10 dBm,17 dBm and 20 dBm respectively.Finally,the experimental results show that when the modulation signal is 2-FSK,the actual threshold is consistent with the threshold calculated by the threshold estimation model in the experimental error range,thus verifying the correctness of the threshold estimation model.This study provides a basis for determining the detection optical power and designing the period,number of tone and sweep range of n-FSK modulated signal in Brillouin optical time domain analysis system using FSK modulation technology.