研究了基于脉冲编码调制的布里渊光时域分析(BOTDA)系统原理,该系统向传感光纤注入经脉冲编码调制后的光脉冲序列,在接收端用数据处理程序恢复系统的单脉冲响应,从而提高BOTDA系统的信噪比、温度和应变分辨率。理论研究了BOTDA系统中Simplex 码、Golay码和CCPONS码的编码和解码原理；利用Matlab仿真研究了不同脉冲编码调制的BOTDA系统的时域输出信号,并对比分析了三种编码对系统信噪比的改善情况,结果表明采用脉冲编码技术可使BOTDA系统性能得到有效提升,CCPONS码调制时可获得最佳系统性能,Simplex码次之。

The principles of Brillouin optical time domain analysis (BOTDA) system based on pulse coding were analyzed. The system launches optical pulse sequence produced by encoded pulse modulation to the sensing fiber and retrieves the singlepulse response with a data processing program at the receiving end of the system,thereby enhancing the signaltonoise ratio,and the temperature/strain resolution of BOTDA system. In order to verify the improvement of system performance,the principles of the encoding and decoding of Simplex code,Golay code and CCPONS code in BOTDA system were analyzed. The time domain output signals of BOTDA system using different pulse code modulations were studied by Matlab simulation,and the improvement of signaltonoise ratio of the system using these three codes were compared. The simulation results show that the pulse coding technique can enhance the performance of BOTDA system effectively and the best system performance can be achieved in CCPONS code modulation system,however the performance of Simplex code modulation system is better than that of Golay code modulation system.