设计了基于拉曼光时域反射技术的船舶电缆分布式光纤测温系统。为了有效提高信号强度, 系统硬件设计中改进了微弱光信号的探测及放大电路, 并且基于FPGA+DSP高速数据处理模块来加快数据处理速度; 针对拉曼反射信号信噪比低的特点, 系统对采集信号采用数字累加平均与自适应阈值小波滤波相结合的去噪方法, 在改善信噪比的同时缩短了测温时间。实验表明, 设计系统测温距离达4km, 空间分辨率为1.5m, 温度分辨率为0.1℃, 系统响应时间为3.8s, 满足设计要求, 且综合指标优异。

Presented is a distributed optical fiber temperature measurement system for ship cable based on Raman scattering. In order to effectively improve the signal strength, the circuit for detecting and amplifying the weak optic signal was optimized, and the FPGA & DSP was adopted to speed up data processing. Aiming at low SNR (signal to noise ratio) of Raman scattering signal, de-noising method of accumulative average and adaptive wavelet threshold filtering were applied to deal with the measured signals, which not only shortens the measurement time but also improves the SNR. Experiments show that the measuring distance of the designed system ranges up to 4km. The temperature accuracy is 0.1℃, the spatial resolution is 1.5m and the response time is about 3.8s, which presents excellent comprehensive performance and satisfies application demands.