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摘要:
针对常见雷达信号调制识别方法在真实场景中难以有效识别未知调制信号的问题,提出一种基于支持向量机(SVM)预训练和K-means聚类的多层级雷达信号开集识别方法。通过将雷达信号进行多重同步压缩(MSST)时频变换后,利用小波变换(DWT)对预处理后的时频图像进行特征提取。在训练阶段,利用已知雷达信号数据来训练一个SVM分类器。在测试阶段,利用该分类器来划分已知调制方式和未知调制方式,并完成已知雷达信号的闭集识别。对未知类信号则利用K-means进行聚类分析,将未知调制方式进一步划分到不同类别,以扩展雷达信号调制方式的识别范围。实验结果表明:所提方法在信噪比(SNR)为−4 dB时对已知信号和未知信号的识别准确率均达到90%以上,实现了对未知调制方式的有效识别。
Abstract:In order to address the issue that traditional radar signal recognition techniques have trouble successfully identifying unknown modulated signals in practical situations, this paper suggests a multi-level radar signal open-set identification technique based on K-means clustering and Support Vector Machine (SVM) pre-training. After performing the multisynchro squeezing transform (MSST) on radar signals, the discrete wavelet transform (DWT) is employed to extract features from the preprocessed time-frequency images. An SVM classifier is trained using known radar signal data during the training phase. The classifier is used to distinguish between known and unknown modulation types during the testing phase in order to achieve open-set radar signal identification. Subsequently, K-means cluster analysis is applied to unknown radar signals, further classifying unknown modulation modes into different clusters, thereby expanding the recognition scope of radar signal modulation types. Experimental results demonstrate that the proposed method achieves a recognition accuracy of over 90% for both known and unknown signals at a signal-to-noise ratio (SNR) of −4 dB, effectively recognizing unknown modulation types.
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表 1 雷达信号参数
Table 1. Radar signal parameters
雷达信号参数 取值 CW载频/MHz 20 QPSK载频/MHz 20 LFM载频/MHz 20 NLFM载频/MHz 20 FSK/BPSK载频/MHz 20 LFM/BPSK载频/MHz 20 LFM/FSK载频/MHz 20 2FSK两频率点选取范围/MHz 10~30 BPSK载频/MHz 20 T1载频/MHz 20 T1序列段数 {4,5,6} 注:采样频率为200 MHz,脉宽为3.5 μm。 -
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