| 摘要: |
| 针对主动声呐在水下环境对目标方位估计受低信噪比的问题，提出了一种基于分数阶傅里叶变换(Fractional Fourier Transform,FrFT改进迭代自适应法的波达方向(Direction of Arrival,DOA估计多波束声呐成像方法。首先对水听器收到的回波信号进行FrFT，通过FrFT预处理将宽带线性调频（Linear Frequency Modulation,LFM信号变换为分数域的窄带信号，避免了交叉干扰项的影响；然后在FrFT域对LFM信号进行聚焦并对噪声进行抑制；最后在FrFT域内实现迭代自适应法，同时优化了功率谱估计方法以精确进行DOA估计。所提方法在低信噪比且不增加传感器阵元的情况下，相较于传统的DOA估计方法具有更好的估计精度与更小的均方根误差，可以显著提高成像效果。仿真结果表明，距离向的峰值旁瓣比可达到-13.364 dB，积分旁瓣比可达到-9.723 dB，方位向的峰值旁瓣比可达到-13.874 dB，积分旁瓣比可达到-10.034 dB。 |
| 关键词: 主动声呐成像 水下波达方向估计 分数阶傅里叶变换 迭代自适应法 |
| DOI：10.20079/j.issn.1001-893x.240506003 |
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| 基金项目:国家自然科学基金资助项目（61561010；广西创新驱动发展专项(桂科AA21077008； 广西无线宽带通信与信号处理重点实验室2022年主任基金项目（GXKL06220102，GXKL06220108；八桂学者专项经费资助（2019A51；桂林电子科技大学研究生教育创新计划资助项目（2023YXW02，YCSW2023317，2022YCXS080 |
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| A DOA Estimation Method for Multi-beam Sonar Imaging Based on Improved Iterative Adaptive Aproach Using FrFT |
| JIANG Liubing,b,YANG Haixin,CHE Li |
| (a.School of Information and Communication;b.Key Laboratory of Wireless Broadband Communication and Signal Processing in Guangxi,Guilin University of Electronic Science and Technology，Guilin 541004,China) |
| Abstract: |
| For the problem of target azimuth estimation under low signal-to-noise ratio(SNR for active sonar in underwater environments,a direction of arrival(DOA estimation multi-beamforming sonar imaging method based on fractional Fourier transform(FrFT-enhanced iterative adaptive approach(IAA is proposed.Firstly,the echo signals received by hydrophones are subjected to FrFT preprocessing,transforming the wideband linear frequency modulation(LFM signals into narrowband signals in the fractional domain to avoid the influence of cross-interference terms.Then,focusing on LFM signals and suppressing noise in the FrFT domain is achieved.Finally,the iterative adaptive method is implemented in the FrFT domain,optimizing the power spectrum estimation method for accurate DOA estimation.Compared with traditional DOA estimation methods,the proposed method achieves better estimation accuracy and smaller root mean square error under low SNR conditions without increasing sensor array elements.It significantly improves imaging effectiveness,as indicated by simulation results showing sidelobe levels -13.364 dB for peak sidelobe ratio.in the range direction and -9.723 dB for integrated sidelobe ratio -13.874 dB for peak sidelobe ratio in the azimuth direction and -10.034 dB for integrated sidelobe ratio. |
| Key words: active sonar imaging underwater DOA estimation fractional Fourier transform iterative adaptive approach |
