短快拍条件下宽带chirp信号的波达方向估计  

DOA estimation for wideband chirp signal with a few snapshots

作　　者：刘德亮[1,2] 刘开华[1] 于洁潇[1] 张良[1] 赵阳[1] 

机构地区：[1]天津大学电子信息工程学院,天津300072 [2]军械工程学院导弹工程系,石家庄050003

出　　处：《计算机应用》2015年第2期351-353,357,共4页journal of Computer Applications

基　　金：国家自然科学基金资助项目(61401301);天津市应用基础与前沿技术研究计划项目(青年基金项目)(14JCQNJC01400)

摘　　要：传统的波达方向(DOA)估计算法角度分辨率低或者依赖于大量的快拍,基于稀疏参数估计的SPICE谱估计算法虽然在很少的快拍数即短快拍条件下就能达到较高的分辨率以及低的旁瓣水平,但是只适用于窄带信号。为了解决上述问题,即仅依靠少量快拍实现对宽带线性调频(chirp)信号的高分辨率DOA估计,提出了一种Fr FTSPICE算法。首先,将宽带chirp信号进行特定阶次的分数阶傅里叶变换(Fr FT),将时域的chirp波形变为Fr FT域的单频正弦波形;其次,推导出Fr FT之后接收信号的方向向量;最后,将方向向量代入到窄带的SPICE算法中,实现对宽带chirp信号的DOA估计。仿真实验中,在少量快拍以及扫描间隔相同的前提下,同多重信号分类(MUSIC)与Fr FT相结合的Fr FT-MUSIC算法相比,Fr FT-SPICE在DOA估计的分辨率方面有所提高;而同将空间重采样(SR)与迭代自适应算法(IAA)相结合的SR-IAA相比,Fr FT-SPICE在估计精度上有所提高。实验结果表明,所提算法能够在短快拍条件下实现对宽带chirp信号的高分辨率、高精度的DOA估计。Conventional Direction-Of-Arrival （DOA） estimation approaches suffer from low angular resolution or relying on a large number of snapshots. The sparsity-based SPICE can work with few snapshots and has high resolution and low sidelobe level, but it only applies to narrowband signals. To solve the above problems, a new FrFT-SPICE method was proposed to estimate the DOA of wideband chirp signals with high resolution based on a few snapshots. First, the wideband chirp signal was taken on the Fractional Fourier Transform （FrFT） under a specific order so that the chirp wave in time domain could be converted into sine wave with single frequency in FrFT domain. Then, the steering vector of the received signal was obtained in FrFY domain. Finally, SPICE algorithm was utilized with the obtained steering vector to estimate the DOA of the wideband chirp. In the simulation with the same scanning grid and same snapshots, the DOA resolution level of the proposed FrFT-SPICE method was better than that of the FrFT-MUSIC method which combines MUltiple Signal Classification （MUSIC） algorithm and FrFT algorithm; and compared to the SR-IAA which utilizes Spatial Resampling （SR） and IAA （ herative Adaptive Approach）, the proposed method had a better accuracy. The simulation results show that the proposed method can estimate the DOA of wideband chirp signals with high accuracy and resolution based on only a few snapshots.

关 键 词：线性调频信号 波达方向 分数阶傅里叶变换 稀疏参数估计 谱估计 

分 类 号：TN911.6[电子电信—通信与信息系统] TP212.9[电子电信—信息与通信工程]