A Time-Frequency Joint Time-Delay Difference Estimation Method for Signal Enhancement in the Distorted towed Hydrophone Array
A Time-Frequency Joint Time-Delay Difference Estimation Method for Signal Enhancement in the Distorted towed Hydrophone Array
复制标题
畸变拖曳式水听器阵列信号增强时频联合时滞差值估计方法
DOI：
10.3390/rs13224586
复制
发表时间：
2021-11-01
期刊：
影响因子：
5
通讯作者：
Cao, Hongli
中科院分区：
文献类型：
--
作者：
Zhu, Chuanqi;Fang, Shiliang;Cao, Hongli
在被动声呐系统中，为了获得阵列形状失真情况下增强的水下舰船辐射噪声信号，通常利用舰船辐射噪声线谱分量的相位差来估计基于波束形成的信号增强的时延差。然而，随着线谱分量信噪比的降低，时延差估计的性能急剧下降。同时，尽管高频线谱分量的时延差估计性能普遍优于低频线谱分量，但高频线谱分量的相位差测量往往容易遇到模量2π模糊的问题。针对上述问题，本文提出了一种新的时频联合时延差估计方法。该方法充分利用时延差随时间缓慢变化的基本特性，建立了对相位差模糊具有鲁棒性的数据驱动隐马尔可夫模型。这样，可用于时延差估计的相位差测量就从单帧低频线谱分量的测量扩展到多帧中所有检测到的线谱分量的测量。该方法利用时间和频率两个维度的相位差测量，即使在低信噪比情况下也能获得增强的时延差估计。仿真和海上实验结果均证明了该方法的有效性。
To acquire the enhanced underwater ship-radiated noise signal in the presence of array shape distortion in a passive sonar system, the phase difference of the line-spectrum component in ship-radiated noise is often exploited to estimate the time-delay difference for the beamforming-based signal enhancement. However, the time-delay difference estimation performance drastically degrades with decreases of the signal-to-noise ratio (SNR) of the line-spectrum component. Meanwhile, although the time-delay difference estimation performance of the high-frequency line-spectrum components is generally superior to that of the low-frequency one, the phase difference measurements of the high-frequency line-spectrum component often easily encounter the issue of modulus 2π ambiguity. To address the above issues, a novel time-frequency joint time-delay difference estimation method is proposed in this paper. The proposed method establishes a data-driven hidden Markov model with robustness to phase difference ambiguity by fully exploiting the underlying property of slowly changing the time-delay difference over time. Thus, the phase difference measurements available for time-delay difference estimation are extended from that of low-frequency line-spectrum components in a single frame to that of all detected line-spectrum components in multiple frames. By jointly taking advantage of the phase difference measurements in both time and frequency dimensions, the proposed method can acquire enhanced time-delay difference estimates even in a low SNR case. Both simulation and at-sea experimental results have demonstrated the effectiveness of the proposed method.