Li Peng, Zhang Xinhua, Zhang Wenlong
Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China.
Key Laboratory of Marine Information Acquisition and Security (Harbin Engineering University), Ministry of Industry and Information Technology, Harbin 150001, China.
Sensors (Basel). 2019 Apr 29;19(9):2001. doi: 10.3390/s19092001.
The traditional passive azimuth estimation algorithm using two hydrophones, such as cross-correlation time-delay estimation and cross-spectral phase estimation, requires a high signal-to-noise ratio (SNR) to ensure the clarity of the estimated target trajectory. This paper proposes an algorithm to apply the frequency diversity technique to passive azimuth estimation. The algorithm also uses two hydrophones but can obtain clear trajectories at a lower SNR. Firstly, the initial phase of the signal at different frequencies is removed by calculating the cross-spectral density matrix. Then, phase information between frequencies is used for beamforming. In this way, the frequency dimension information is used to improve the signal processing gain. This paper theoretically analyzes the resolution and processing gain of the algorithm. The simulation results show that the proposed algorithm can estimate the target azimuth robustly under the conditions of a single target (SNR = -16 dB) and multiple targets (SNR = -10 dB), while the cross-correlation algorithm cannot. Finally, the algorithm is tested by the swell96 data and the South Sea experimental data. When dealing with rich frequency signals, the performance of the algorithm using two hydrophones is even better than that of the conventional broadband beamforming of the 64-element array. This further validates the effectiveness and advantages of the algorithm.
传统的使用两个水听器的被动方位估计算法，如互相关时延估计和互谱相位估计，需要高信噪比（SNR）来确保估计目标轨迹的清晰度。本文提出一种将频率分集技术应用于被动方位估计的算法。该算法同样使用两个水听器，但能在较低信噪比下获得清晰的轨迹。首先，通过计算互谱密度矩阵去除不同频率信号的初始相位。然后，利用频率间的相位信息进行波束形成。通过这种方式，利用频率维度信息提高信号处理增益。本文从理论上分析了该算法的分辨率和处理增益。仿真结果表明，所提算法能在单目标（SNR = -16 dB）和多目标（SNR = -10 dB）条件下稳健地估计目标方位，而互相关算法则不能。最后，利用swell96数据和南海实验数据对该算法进行测试。在处理丰富频率信号时，使用两个水听器的该算法性能甚至优于传统的64元阵列宽带波束形成。这进一步验证了该算法的有效性和优势。
