﻿ 一种导航雷达辐射源细微特征提取方法
 舰船科学技术  2024, Vol. 46 Issue (10): 147-151    DOI: 10.3404/j.issn.1672-7649.2024.10.025 PDF

LAN Tian-liang, MAO Yu-long, YANG Ming-yuan
The 724 Research Institute of CSSC, Nanjing 210000, China
Abstract: Aiming at the low accuracy of recognition of navigation radar emitter by conventional methods, the time-frequency characteristics of pulse signals and unintentional modulation on pulse of navigation radar were analyzed and studied, focusing on the instantaneous frequency of pulse signals, especially at the rising and falling edges of pulses. The change rate of instantaneous frequency was characterized by taking a series of sampling point composition vectors and using support vector machine for classification. Experiments based on simulation data showed that, Compared with the whole pulse, this method can distinguish different radar emitter signals better, which not only improves the recognition accuracy, but also reduces the calculation amount. The method obtains satisfactory results in single carrier frequency signal, linear frequency modulation signal and binary phase-coded signal. Using the actual data collection verification, when the SNR is 20dB, the recognition accuracy is more than 90%.
Key words: subtle feature extraction     instantaneous frequency feature     support vector machines
0 引　言

1 信号建模仿真 1.1 简单信号分析

 $\begin{split} x(n)= & [A+\Delta A(n)]\mathrm{exp}[j({\phi }_{0}+2{\text π} {f}_{c}n+\phi (n)+\\ & \Delta \phi (n))]+w(n),n\in [0,N-1]。\end{split}$ (1)

1） 单载频信号，频率不变则相位不变，$\phi \left(n\right)$=0；

2） 线性调频信号，$\phi \left(n\right)={\text π} K{n}^{2}$K为调频斜率；

3） 二相编码信号，$\phi \left(n\right)={\text π} c\left(n\right) $$c\left(n\right)\in \{0,1\}。 \Delta A\left(n\right)$$ \Delta \phi \left(n\right)$是由雷达发射机硬件差异引起的幅度和相位无意调制，可以反应出个体差异，由于幅度调制不如相位调制明显，而且相位的变化可以反映到频率的变化上，因此本文忽略幅度调制并且着重关注频率的变化，式（1）改写成

 $x\left(n\right) = A\mathrm{exp}\left[j\left({\phi }_{0} + 2{\text π} {f}_{c}\left(n\right)n\right)\right] + w\left(n\right),n\in \left[0,N - 1\right]。$ (2)

 图 1 单载频脉冲信号示意图 Fig. 1 Schematic diagram of single carrier frequency pulse signal
1.2 仿真信号生成

 图 2 3部雷达上升沿的频率 Fig. 2 The rising edge frequency of three radar
2 特征提取与分类识别

3 实验结果 3.1 不同信号对比

 图 3 3部雷达分类结果的混淆矩阵 Fig. 3 The confusion matrix of three radar classification results

3.2 参数寻优

3.3 与其他算法对比

 图 4 不同算法在不同信噪比下的正确率 Fig. 4 The accuracy of three method in different SNR

4 结　语

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