Collaborative Nonlinear Space-time Adaptive Processing and Pulse Compression Based on Neural Networks
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摘要: 在复杂目标和杂波环境下,传统机载雷达脉冲压缩和空时自适应处理均受限于预设线性模型而存在性能损失问题。针对该问题,该文提出一种基于深度学习的空时自适应-脉冲压缩联合处理技术,通过构建空时谱超分辨网络和脉冲压缩网络分别实现非线性杂波空时谱估计及非线性脉压,从而显著降低该信号处理流程中模型失配的影响,实现杂波抑制和目标检测性能的提升。同时,为避免非线性脉压在阵元和脉冲间引入相位误差的问题,该文从数学角度分析和讨论了脉压后置的可行性。在所提先滤波再脉压的非线性联合处理架构中,采用多模块卷积神经网络分别实现高分辨空时谱估计以及脉冲压缩处理,且所构建各网络模块功能均与相应数学解析式对应,因此具较高的可靠性。仿真实验结果表明,在密集弱目标和小样本环境下,所提非线性联合处理架构较相应传统处理流程可获得约20 dB的信杂噪比提升。
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关键词:
- 非线性信号处理 /
- 空时自适应处理(STAP) /
- 脉冲压缩 /
- 卷积神经网络(CNN) /
- 杂波抑制 /
- 目标检测
Abstract: Traditional airborne radar Pulse Compression (PC) and Space-Time Adaptive Processing (STAP) suffer performance degradation in complex target and clutter environments due to their reliance on predefined linear models. To address this issue, we developed a deep learning-based joint STAP-PC technique. This approach employed dedicated networks—a super-resolution space-time spectrum network for nonlinear clutter estimation and a PC network for nonlinear PC. The proposed architecture effectively mitigated model mismatch within the processing chain, leading to improved clutter suppression and target detection. Notably, we mathematically established the feasibility of post-pulse compensation to prevent nonlinear PC from introducing phase errors across elements and pulses. The implemented architecture utilized multimodule convolutional neural networks for super-resolution space-time spectrum estimation and PC, with each module’s functionality demonstrating clear mathematical correspondence, thereby ensuring the reliability of the overall processing chain. Simulation results revealed that in scenarios with dense weak targets and limited samples, the proposed nonlinear joint processing technique improved signal-to-clutter-plus-noise ratio by approximately 20 dB over traditional methods. -
表 1 非线性空时谱超分辨网络运算复杂度分析
Table 1. Analysis of computational complexity of nonlinear STAP spectrum estimation network
方法 运算复杂度 运行时间(s) FOCUSS $ O\left( {\left( {NK{N_{\text{S}}}{N_{\text{D}}} + {{\left( {NK} \right)}^3} + 2{{\left( {NK} \right)}^2}{N_{\text{S}}}{N_{\text{D}}} + NK{{\left( {{N_{\text{S}}}{N_{\text{D}}}} \right)}^2}} \right){I_{{\text{FOC}}}}} \right) $ 61.87 SBL $ O\left( {\left( {NK{N_{\text{S}}}{N_{\text{D}}} + {{\left( {NK} \right)}^3} + 3{{\left( {NK} \right)}^3}{N_{\text{S}}}{N_{\text{D}}} + 2NK{{\left( {{N_{\text{S}}}{N_{\text{D}}}} \right)}^2}} \right){I_{{\text{SBL}}}}} \right) $ 130.40 CNN $ O\left( {{\text{28777 }}{N_{\text{S}}}{N_{\text{D}}}} \right) $ 1.53 所提非线性空时谱估计方法 $ O\left( {{\text{12960 }}{N_{\text{S}}}{N_{\text{D}}}} \right) $ 0.79 表 2 脉冲压缩网络运算复杂度分析
Table 2. Analysis of computational complexity of end-to-end pulse compression network
方法 运算复杂度 运行时间(s) MF $O(P)$ 0.02 APC $O({P^3})$ 1.70 DC-APC $O({P^3})$ 1.83 所提非线性脉冲压缩 $O(3744P)$ 0.18 表 3 雷达系统参数
Table 3. Radar system parameters
参数 数值 参数 数值 飞行高度 3000 m信号带宽 2.5 MHz 飞行速度 60 m/s 信号脉宽 32 μs 载波频率 9 GHz 脉冲重复频率 2500 Hz阵元数 8 主波束方位角 0o 脉冲数 16 主波束俯仰角 5o 表 4 目标参数
Table 4. Targets parameters
目标 距离门 SNR (dB) 多普勒频移(Hz) 目标1 46 25 120 目标2 51 29 1200 目标3 56 27 1920 表 5 各对比方法的APSL (dB)
Table 5. APSL of each comparison method (dB)
目标 MF APC DC-APC CNN-APC GT 目标1 28.86 30.55 41.41 48.07 53.58 目标2 32.86 45.01 49.30 51.68 57.48 目标3 30.90 45.56 48.10 49.20 55.37 -
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