Research On Slope-assisted BOTDR Detector

With the development of distributed optical fiber sensing technology,diversified performance requirements have gradually become the focus of research.Traditional Brillouin Optical Time Domain Reflectometer(BOTDR)technology is usually used in structural health monitoring of large structures,long-distance pipelines and power lines.However,with the development of engineering application research,distributed short-range and high-precision real-time strain/temperature monitoring has become a research hotspot.Conventional fast BOTDR usually adopts fast time-frequency analysis,usually FFT method.However,due to the huge amount of computing data,the cost of real-time measurement is high.In this paper,the real-time measurement of BOTDR was successfully realized by referring to the more mature slop-assisted method in Brillouin optical time domain analysis technology,and some optimization and in-depth research were carried out on the scheme:(1)In this paper,the sensing mechanism of Brillouin scattering signals is firstly analyzed,and the traditional sweep BOTDR and short-time Fourier transform BOTDR are analyzed and compared,and the speed restriction factors are summarized,the feasibility and advantages of slop-assisted BOTDR(sa-botdr)are theoretically analyzed,and the detection structure and system of sa-botdr are designed.(2)Design the overall software of SA-BOTDR through demand analysis;The measurement processing steps are analyzed,and the extraction algorithm of Brillouin gain spectrum during calibration and the selection of working frequency points and signal demodulation processing algorithm during slope assisted multiple measurements are studied respectively.Finally through MFC completed the specific design and development of each module of the software.(3)Based on the previously designed system structure,the selection of each device was carried out,and the SA-BOTDR system was finally built,and the measurement scheme was designed.Through preliminary experiments,it was confirmed that the scheme was basically consistent with the goal of theoretical research,and it proved that the slope assisted method had a significant effect on the improvement of demodulation speed.(4)the analysis of the results of preliminary experiments,it is concluded that the data acquisition of wide bandwidth and signal-to-noise contrast,through the analysis of signal characteristics of SA-BOTDR,power detection scheme based on multistage amplifier was designed,the successful lower acquisition bandwidth at the same time,improves the signal-tonoise ratio,and through the theoretical research and experimental analysis to optimize the performance of SA-BOTDR system,finally completed the measurement range,measurement accuracy,the spatial resolution and the analysis of the measurement speed,comprehensive evaluation of the performance of SA-BOTDR.