Li Zhengyang, Zhang Yangan, Yuan Xueguang, Xiao Zhenyu, Zhang Yuan, Huang Yongqing
School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China.
Sensors (Basel). 2023 Oct 20;23(20):8612. doi: 10.3390/s23208612.
In the domain of optical fiber distributed acoustic sensing, the persistent challenge of extending sensing distances while concurrently improving spatial resolution and frequency response range has been a complex endeavor. The amalgamation of pulse compression and frequency division multiplexing methodologies has provided certain advantages. Nevertheless, this approach is accompanied by the drawback of significant bandwidth utilization and amplified hardware investments. This study introduces an innovative distributed optical fiber acoustic sensing system aimed at optimizing the efficient utilization of spectral resources by combining compressed pulses and frequency division multiplexing. The system continuously injects non-linear frequency modulation detection pulses spanning various frequency ranges. The incorporation of non-uniform frequency division multiplexing augments the vibration frequency response spectrum. Additionally, nonlinear frequency modulation adeptly reduces crosstalk and enhances sidelobe suppression, all while maintaining a favorable signal-to-noise ratio. Consequently, this methodology substantially advances the spatial resolution of the sensing system. Experimental validation encompassed the multiplexing of eight frequencies within a 120 MHz bandwidth. The results illustrate a spatial resolution of approximately 5 m and an expanded frequency response range extending from 1 to 20 kHz across a 16.3 km optical fiber. This achievement not only enhances spectral resource utilization but also reduces hardware costs, making the system even more suitable for practical engineering applications.
在光纤分布式声学传感领域，在扩展传感距离的同时提高空间分辨率和频率响应范围这一长期存在的挑战一直是一项复杂的工作。脉冲压缩和频分复用方法的结合带来了一定优势。然而，这种方法存在带宽利用率高和硬件投资增加的缺点。本研究介绍了一种创新的分布式光纤声学传感系统，旨在通过结合压缩脉冲和频分复用优化频谱资源的有效利用。该系统连续注入跨越不同频率范围的非线性调频检测脉冲。非均匀频分复用的加入扩展了振动频率响应谱。此外，非线性调频巧妙地减少了串扰并增强了旁瓣抑制，同时保持了良好的信噪比。因此，这种方法大幅提高了传感系统的空间分辨率。实验验证包括在120 MHz带宽内对八个频率进行复用。结果表明，在16.3公里的光纤上，空间分辨率约为5米，频率响应范围从1 kHz扩展到20 kHz。这一成果不仅提高了频谱资源利用率，还降低了硬件成本，使该系统更适合实际工程应用。
