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瑞利布里渊光时域分析系统(BOTDA)存在信号小、噪声大的问题,会导致系统空间分辨率与信噪比难以同时提高。将脉冲编码技术引入瑞利BOTDA系统,可在不降低空间分辨率的前提下有效地提高系统信噪比和布里渊频移测量精度。分析了瑞利BOTDA温度传感系统的原理,介绍了Golay互补序列的特性,并给出了单脉冲和编码脉冲系统的信噪比表达式;搭建了单脉冲和脉冲编码瑞利BOTDA温度传感系统,测量了单脉冲瑞利BOTDA系统的温度传感特性及脉冲编码瑞利BOTDA系统的空间分辨率和温度测量精度。实验结果表明,由瑞利BOTDA系统获得的布里渊频移与温度呈良好的线性关系,温度系数为(1.109±0.010)MHz·℃-1;当采用10ns脉冲宽度、64bit格雷编码时,在1.77km光纤的加温段上实现了空间分辨率为1m、温度测量精度为1.39℃的传感测量。
Rayleigh Brillouin optical time-domain analysis system (BOTDA) there is a small signal, the problem of large noise, will lead to the system spatial resolution and signal to noise ratio is difficult to improve at the same time. The introduction of pulse coding technology into Rayleigh BOTDA system can effectively improve the system SNR and Brillouin frequency shift measurement accuracy without reducing the spatial resolution. The principle of Rayleigh BOTDA temperature sensing system is analyzed, the characteristics of Golay complementary sequence are introduced, and the expressions of signal-to-noise ratio of single pulse and coded pulse system are given. Single pulse and pulse code Rayleigh BOTDA temperature sensing System, the temperature sensing characteristics of the single pulse Rayleigh BOTDA system and the spatial resolution and temperature measurement accuracy of the pulse code Rayleigh BOTDA system were measured. The experimental results show that the Brillouin frequency shift obtained by Rayleigh BOTDA system has a good linear relationship with temperature, with a temperature coefficient of (1.109 ± 0.010) MHz · ℃ -1. When 10ns pulse width and 64-bit Gray coding are used, 1.77km optical fiber heating section to achieve a spatial resolution of 1m, the temperature measurement accuracy of 1.39 ℃ for the sensing measurement.