基于多域雷達(dá)回波數(shù)據(jù)融合的海面小目標(biāo)分類網(wǎng)絡(luò)模型
doi: 10.11999/JEIT240818 cstr: 32379.14.JEIT240818
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西安電子科技大學(xué)雷達(dá)信號(hào)處理全國(guó)重點(diǎn)實(shí)驗(yàn)室 西安 710071
A Network Model for Sea Surface Small Targets Classification Based on Multidomain Radar Echo Data Fusion
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National Key Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China
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摘要: 海面小目標(biāo)識(shí)別是海事雷達(dá)監(jiān)視任務(wù)中一個(gè)重要且具有挑戰(zhàn)性的問(wèn)題。由于海面小目標(biāo)類型多樣、環(huán)境復(fù)雜多變,對(duì)其進(jìn)行有效分類存在較大困難。在高分辨體制雷達(dá)下,海面小目標(biāo)通常只占據(jù)一或幾個(gè)距離單元,缺乏足夠的空間散射結(jié)構(gòu)信息,因此目標(biāo)的雷達(dá)截面積(RCS)起伏和徑向速度變化成為分類的主要依據(jù)。為此,該文提出一種基于多域雷達(dá)回波數(shù)據(jù)融合的分類網(wǎng)絡(luò)模型,用于海面小目標(biāo)的分類任務(wù)。由于不同域的數(shù)據(jù)具有其特殊的物理意義,因此該文構(gòu)建了時(shí)域LeNet(T-LeNet)神經(jīng)網(wǎng)絡(luò)模塊和時(shí)頻特征提取神經(jīng)網(wǎng)絡(luò)模塊,分別從雷達(dá)海面回波信號(hào)的幅度序列和時(shí)頻分布(TFD)即時(shí)頻圖中提取特征。其中幅度序列主要反映了目標(biāo)RCS的起伏特性,而時(shí)頻圖不僅反映RCS起伏特性,還能體現(xiàn)目標(biāo)徑向速度的變化。最后,利用IPIX, CSIR數(shù)據(jù)庫(kù)和自測(cè)的無(wú)人機(jī)數(shù)據(jù)集構(gòu)建了包括4種海面小目標(biāo)的數(shù)據(jù)集:錨定漂浮小球、漂浮船只、低空無(wú)人機(jī)(UAV)和移動(dòng)的快艇。實(shí)驗(yàn)結(jié)果表明所提方法具有良好的識(shí)別能力。
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關(guān)鍵詞:
- 海面小目標(biāo) /
- 目標(biāo)分類 /
- 多特征融合 /
- 神經(jīng)網(wǎng)絡(luò)
Abstract:Objective Small target recognition on the sea surface is a critical and challenging task in maritime radar surveillance. The variety of small targets and the complexity of the sea surface environment make their classification difficult. Due to the small size of these targets, typically occupying only one or a few range cells under high-resolution radar systems, there is insufficient spatial scattering structure information for classification. The primary information for classification comes from the target’s Radar Cross Section (RCS) fluctuation and radial velocity change. This study proposes a classification network model based on multidomain radar echo data fusion, providing a theoretical foundation for small target recognition in complex sea surface environments. Methods A small marine target classification network model is proposed, based on multidomain radar echo data fusion, incorporating both time domain and time-frequency domain. Given that data from different domains hold distinct physical significance, a Time-domain LeNet (T-LeNet) neural network module and a time-frequency feature extraction neural network module are designed to extract features from the amplitude sequence and the Time-Frequency Distribution (TFD), respectively. The amplitude sequence primarily reflects the fluctuation characteristics of the target’s RCS, while the TFD captures both the RCS fluctuations and variations in the target’s radial velocity. By extracting deep information from small sea surface targets, effective differential features are obtained, leading to improved classification results. The advantages of the multidomain data fusion approach are validated through ablation experiments, where the amplitude sequence is fused with the input TFD, or the TFD is fused with the input amplitude sequence. Additionally, the effect of network depth on recognition performance is explored by using ResNet architectures with varying depths for time-frequency feature extraction. Results and Discussions A dataset containing four types of small sea surface targets is constructed using measured data to evaluate the effectiveness of the proposed method. Six evaluation metrics are used to assess the model’s classification ability. The experimental results show that when only the TFD is input, the best recognition performance is achieved by the ResNet18 network. This is due to ResNet18’s ability to prevent gradient vanishing and explosion through residual connections, enabling a deeper network capable of more effectively extracting differential features between targets. When only the amplitude sequence is input, the recognition performance of the T-LeNet network improves significantly compared to the performance with only the TFD input. Fusing the amplitude sequence with the T-LeNet network, based solely on the input of the TFD, leads to a notable increase in recognition performance. Thus, incorporating information from other domains, such as time-domain information (amplitude sequence), and extracting abstract features from one-dimensional data with T-LeNet, while also capturing deeper target features from multidomain and multidimensional aspects, significantly enhances the network’s recognition capability. The best recognition performance occurs when both the amplitude sequence and TFD are input using the ResNet18 network, achieving an accuracy of 97.21%, which represents a 21.1% improvement over the TFD-only input with the Vgg16 network ( Table 3 ). The confusion matrix reveals that Class I and Class II targets are more accurately classified when using only the amplitude sequence, with average accuracy improvements of 5.5% and 85.1%, respectively, compared to the TFD-only input. Class IV targets are better classified when using only the TFD, with an average accuracy improvement of 5.5% compared to the amplitude sequence input. There is no significant difference in the accuracy of Class III targets (Fig. 5 ). Comparing the classification results of different ResNet networks shows that increasing the depth of the ResNet network does not significantly enhance recognition performance (Table 4 ). Analyzing the loss and accuracy of the various experiments in both the training and validation sets reveals that combining the T-LeNet network improves performance further. Specifically, the accuracy of AlexNet, Vgg16, and ResNet18 in the validation set improves by approximately 7.7%, 5.3% and 3.6%, respectively, while the loss in both the training and validation sets decreases (Fig. 6 ).Conclusions This paper proposes a small sea surface target classification method based on Convolutional Neural Networks (CNN) and data fusion. The method considers both the time domain and time-frequency domain, leveraging their distinct physical significance. It constructs the T-LeNet network module and the time-frequency feature extraction network module to extract deep information from small sea surface targets across multiple domains and dimensions. The abstract features jointly extracted from the time domain and time-frequency domain are fused for multidomain and multidimensional classification. The experimental results demonstrate that the proposed method exhibits strong recognition capability for small sea surface targets. -
Key words:
- Sea Surface Small target /
- Target classification /
- Multi-feature fusion /
- Neural network
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表 1 4類目標(biāo)與其對(duì)應(yīng)的雷達(dá)參數(shù)
目標(biāo)類型 數(shù)據(jù)來(lái)源 距離分辨率(m) 重頻(kHz) 載頻(GHz) 極化方式 工作模式 波束寬度(°) 海況(級(jí)) 訓(xùn)練樣本數(shù) 測(cè)試樣本數(shù) 錨定漂浮小球 IPIX93 30 1 9.39 HH/HV/VH/VV 駐留模式 0.9 2/3 21940 6560 漂浮船只 IPIX98 30 1 9.39 HH/HV/VH/VV 駐留模式 0.9 / 12768 3416 低空無(wú)人機(jī) 靈山島 3 4 10.00 HH/VV 駐留模式 1.1 2 7569 1 893 移動(dòng)的快艇 CSIR 15 2.5/5 6.90 VV 跟蹤模式 1.8 3 2920 964 下載: 導(dǎo)出CSV
表 2 混淆矩陣
預(yù)測(cè)類別 目標(biāo)1 目標(biāo)2 目標(biāo)3 目標(biāo)4 真實(shí)類別 目標(biāo)1 T1P1 F1P2 F1P3 F1P4 目標(biāo)2 F2P1 T2P2 F2P3 F2P4 目標(biāo)3 F3P1 F3P2 T3P3 F3P4 目標(biāo)4 F4P1 F4P2 F4P3 T4P4 下載: 導(dǎo)出CSV
表 3 不同實(shí)驗(yàn)在6個(gè)評(píng)價(jià)指標(biāo)下的分類結(jié)果
準(zhǔn)確率 誤差 精確度 召回率 F1-measure Kappa 時(shí)頻圖+AlexNet 0.7773 0.2227 0.8139 0.7912 0.8024 0.6403 時(shí)頻圖+Vgg16[5] 0.8022 0.1978 0.8461 0.8202 0.8330 0.6792 時(shí)頻圖+ResNet18 0.8145 0.1855 0.8487 0.8238 0.8361 0.7006 幅度序列+T-LeNet 0.9250 0.0750 0.9145 0.9130 0.9138 0.8823 幅度序列+時(shí)頻圖+T-LeNet+AlexNet 0.9426 0.0574 0.9440 0.9528 0.9484 0.9106 幅度序列+時(shí)頻圖+T-LeNet+Vgg16 0.9549 0.0451 0.9558 0.9578 0.9568 0.9296 幅度序列+時(shí)頻圖+T-LeNet+ResNet18 0.9721 0.0279 0.9708 0.9776 0.9742 0.9567 下載: 導(dǎo)出CSV
表 4 不同ResNet網(wǎng)絡(luò)在6個(gè)評(píng)價(jià)指標(biāo)下的分類結(jié)果
準(zhǔn)確率 誤差 精確度 召回率 F1-measure Kappa 時(shí)頻圖+ResNet18 0.8145 0.1855 0.8487 0.8238 0.8361 0.7006 時(shí)頻圖+ResNet34 0.8245 0.1755 0.8677 0.8379 0.8525 0.7165 時(shí)頻圖+ResNet50 0.8202 0.1798 0.8619 0.8359 0.8487 0.7100 幅度序列+時(shí)頻圖+T-LeNet+ResNet18 0.9721 0.0279 0.9708 0.9776 0.9742 0.9567 幅度序列+時(shí)頻圖+T-LeNet+ResNet34 0.9726 0.0274 0.9729 0.9775 0.9752 0.9574 幅度序列+時(shí)頻圖+T-LeNet+ResNet50 0.9736 0.0264 0.9707 0.9777 0.9742 0.9589 下載: 導(dǎo)出CSV
表 5 網(wǎng)絡(luò)的參數(shù)量、訓(xùn)練時(shí)間、測(cè)試時(shí)間和單個(gè)樣本測(cè)試時(shí)間
網(wǎng)絡(luò) 參數(shù)量(M) 訓(xùn)練時(shí)間(min) 測(cè)試時(shí)間(s) 單個(gè)樣本測(cè)試時(shí)間(ms) T-LeNet 8.4669 7.25 23.87 1.86 AlexNet 61.1048 87.13 46.97 3.66 Vgg16 138.3651 216.15 55.05 4.29 ResNet18 11.1786 120.12 45.94 3.58 ResNet34 21.2867 195.19 72.65 5.66 ResNet50 23.5162 330.33 136.33 10.62 T-LeNet+AlexNet 71.7922 95.37 51.46 4.01 T-LeNet+Vgg16 149.0489 233.67 59.67 4.65 T-LeNet+ResNet18 21.7429 130.32 50.69 3.95 T-LeNet+ResNet34 31.8511 203.62 85.37 6.65 T-LeNet+ResNet50 34.4677 342.09 145.39 11.33 下載: 導(dǎo)出CSV
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