格雷互补序列在BOTDR中的应用研究及性能分析

在基于布里渊散射的光时域反射计中,信噪比和空间分辨率是一对一直未能解决的相互制约的因素,而扩频技术是一种常用的提高信噪比的方法。格雷(Golay)互补序列具有好的时域构成特性和频域互补特性,经过适当的信号变换后可以作为一种扩频技术用作光纤传感系统的探测信号。详细讨论了如何在光系统中使用单极性脉冲达到双极性脉冲的效果,并在此基础上设计了一个使用Golay互补序列作为探测脉冲的外差检测式光纤传感系统,在10 km传感距离1 m空间分辨率的基础上,获得了0.41 K的温度分辨率和7.4με的应变分辨率,并定性给出了系统的仿真结果。分析表明使用Golay互补序列作为光纤传感系统的探测脉冲既可以提高系统的信噪比、温度和应变分辨率等性能又不降低系统的空间分辨率。

The application research and performance analysis of BOTDR using Golay complementary sequences

The restriction relationship of signal-to-noise ratio(SNR) and spatial resolution have not been resolved in Brillouin optical time domain reflectometer,and spread-spectrum techniques is often used to improve SNR.Golay complementary sequences have better constitution performance in time domain and cross complement performance in frequency domain.It can be used as the probing pulse in fiber sensing system after proper transformation.This paper has discussed how to use single polar pulse in optical system as the same result with bipolar pulsein detail,and a heterodyne detection fiber sensing system using Golay complementary sequences as probing pulses was designed.Based on a 10 km sensing fiber, a temperature resolution of 0.41 K and strain resolution of 7.4 με were achieved with a spatial resolution of 1 m.And a simulation result of the system was given in performance.It is proved that using Golay complementary sequences as probing pulses of fiber sensing system can improve system performances such as signal-to-noise ratio,temperature and strain resolution without degrading spatial resolution.