High Speed Multi-target Parameter Estimation for FA-OFDM Radar Based on Expectation Maximization Algorithm
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摘要:
参数估计对雷达的目标检测和识别有着重要的意义。该文提出了一种基于期望最大化(EM)算法的捷变频联合正交频分复用(FA-OFDM)雷达高速多目标参数估计方法。首先，将窄带正交频分复用(OFDM)信号与传统捷变频雷达相结合，在每个脉冲宽度内同时发射多个载频随机跳变的子载波。然后，对单个脉冲内所有子载波的回波进行脉冲压缩和稀疏重构处理，得到1维高分辨距离。进一步地，将多个目标在不同脉冲时刻的高分辨距离信息构成观测数据，建立混合高斯模型。采用EM算法对模型参数和多个目标的距离、速度进行估计，并同时拟合多条时间-距离直线。直线斜率对应目标速度，直线纵轴截距对应目标初始距离。最终，分别分析了信噪比(SNR)对检测概率以及目标速度对相对估计误差的影响。仿真实验验证了所提算法的有效性。
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关键词:
- 捷变频联合正交频分复用雷达 /
- 参数估计 /
- 高速多目标 /
- EM算法
Abstract:Parameter estimation is very important for radar to detect and recognize targets. In this paper, a high speed multi-target parameter estimation method for Frequency Agility-Orthogonal Frequency Division Multiplexing(FA-OFDM) radar based on Expectation Maximization(EM) algorithm is proposed. Firstly, a promising idea is to combine narrowband Orthogonal Frequency Division Multiplexing (OFDM) signals and frequency agility, multiple subcarriers that frequency hopping randomly are simultaneously transmitted within each pulse width. Then, all echoes of a single pulse are compressed and sparsely reconstructed to achieve 1-demension high range resolution. Subsequently, the high resolution range of multiple targets at each pulse time are obtained to constitute the observation data, and Gauss mixture model is established. EM algorithm is applied to estimate the parameters of the model and the range and velocity of multiple targets. Also, multiple time-range lines are fitted at the same time, and the slope of the line corresponds to the velocity of the target, as well as, the vertical intercept of the line corresponds to the initial range of the target, separately. Finally, the influence of the Signal-to-Noise Ratio (SNR) on detection probability and the target velocity on relative error of estimation are analyzed, respectively. Simulations are provided to verify the effectiveness of the proposal.
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表 1 仿真参数
参数 数值 参数 数值 脉冲宽度 4 μs 脉冲重复频率 25 kHz 信号带宽 24 MHz 采样频率 48 MHz 子载波个数 64 中心载频 14 GHz 跳频总数 128 跳频带宽 20 MHz 脉冲总数 64 信噪比 –12 dB 目标距离 [3994,4001,4006] m 目标速度 [600,1220,5800] m/s 
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