He Xiangge, Zhang Min, Gu Lijuan, Xie Shangran, Liu Fei, Lu Hailong
College of Engineering, Peking University, Beijing 100871, China.
Beijing International Center for Gas Hydrate, Peking University, Beijing 100871, China.
Sensors (Basel). 2020 Feb 13;20(4):999. doi: 10.3390/s20040999.
Phase fading is fatal to the performance of distributed acoustic sensors (DASs) influencing its capability of distributed measurement as well as its noise level. Here, we report the experimental observation of a strong negative correlation between the relative power spectrum density (PSD) at the heterodyne frequency and the noise floor of the detected phase for the heterodyne demodulated distributed acoustic sensor (HD-DAS) system. We further propose a weighted-channel stack algorithm (WCSA) to alleviate the phase fading noise via an enhancement of the relative PSD at the heterodyne frequency. Experimental results show that the phase noise of the demodulated signal can be suppressed by 13.7 dB under optimal condition. As a potential application, we exploited the improved HD-DAS system to retrieve a piece of music lasted for 205 s, demonstrating the reliability of detecting wideband sound signal without distortion.
相位衰落对于分布式声学传感器（DAS）的性能来说是致命的，它会影响其分布式测量能力以及噪声水平。在此，我们报告了外差解调分布式声学传感器（HD-DAS）系统中，外差频率处的相对功率谱密度（PSD）与检测到的相位的本底噪声之间存在强负相关的实验观测结果。我们进一步提出了一种加权通道叠加算法（WCSA），通过增强外差频率处的相对PSD来减轻相位衰落噪声。实验结果表明，在最佳条件下，解调信号的相位噪声可被抑制13.7 dB。作为一种潜在应用，我们利用改进后的HD-DAS系统恢复了一段时长为205秒的音乐，证明了检测宽带声音信号且不失真的可靠性。
