低信噪比下天基预警雷达空中目标相对运动参数估计方法
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摘要
天基预警雷达空中目标回波在杂波抑制后,仍然存在脉间包络距离徙动和多普勒扩散现象,导致相参积累后回波能量在距离单元和多普勒域散焦。为了提高相参积累的增益,必须估计出卫星平台和空中目标间的相对运动参数,从而对回波信号进行补偿。由于星载雷达功率孔径积有限,且雷达和目标的距离较远,回波信号的信噪比一般较低,给运动参数的估计精度造成了影响。针对这一问题,本文提出了一种低信噪比下运动参数的估计方法。首先建立了空中目标的回波模型,并计算了雷达视距范围内的回波信噪比范围;然后介绍并利用Keystone变换校正回波包络的距离徙动,得到目标所在距离单元内的方位时域信号;最后利用Gabor变换得到方位时域信号的时频分布,再通过标准Hough变换将时频分布由时频域变换到参数域,最终得到运动参数的估计值。仿真结果表明,本文方法在低信噪比下能有效地估计目标运动参数,并且估计精度对信噪比的变化不敏感,具有良好的鲁棒性。
After the clutter suppression,the space target echo of the space-based early warning radar still has inter-pulse envelope migration and Doppler diffusion,which causes the echo energy to defocus in the distance unit and Doppler domain after coherent accumulation. In order to increase the gain of coherent accumulation,the relative motion parameters between the satellite platform and the air target must be estimated to compensate the echo signal. Due to the limited power aperture product of the spaceborne radar and the long distance between the radar and the target,the signal-to-noise ratio of the echo signal is generally low,which affects the estimation accuracy of the motion parameters. Aiming at this problem,this paper proposes a method for estimating the motion parameters under low SNR. Firstly,the echo model of the air target is established,and the echo signal-to-noise ratio range in the radar line-of-sight range is calculated. Then,the Keystone transform is used to correct the distance migration of the echo envelope to obtain the azimuth time-domain signal; finally,the timefrequency distribution of the azimuth time-domain signal is obtained by Gabor transform,and then the time-frequency domain is transformed from the time-frequency domain to the parameter domain by standard Hough transform,and finally the estimated value of the motion parameter is obtained. The simulation results show that the proposed method can effectively estimate the target motion parameters under low SNR,and the estimation accuracy is not sensitive to the change of SNR,and it has good robustness.
After the clutter suppression,the space target echo of the space-based early warning radar still has inter-pulse envelope migration and Doppler diffusion,which causes the echo energy to defocus in the distance unit and Doppler domain after coherent accumulation. In order to increase the gain of coherent accumulation,the relative motion parameters between the satellite platform and the air target must be estimated to compensate the echo signal. Due to the limited power aperture product of the spaceborne radar and the long distance between the radar and the target,the signal-to-noise ratio of the echo signal is generally low,which affects the estimation accuracy of the motion parameters. Aiming at this problem,this paper proposes a method for estimating the motion parameters under low SNR. Firstly,the echo model of the air target is established,and the echo signal-to-noise ratio range in the radar line-of-sight range is calculated. Then,the Keystone transform is used to correct the distance migration of the echo envelope to obtain the azimuth time-domain signal; finally,the timefrequency distribution of the azimuth time-domain signal is obtained by Gabor transform,and then the time-frequency domain is transformed from the time-frequency domain to the parameter domain by standard Hough transform,and finally the estimated value of the motion parameter is obtained. The simulation results show that the proposed method can effectively estimate the target motion parameters under low SNR,and the estimation accuracy is not sensitive to the change of SNR,and it has good robustness.
引文
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[13]张辉,范雪林,李东风.一种改进的短时傅里叶算法实现[J].通信技术,2017,50(5):1066-1068.Zhang Hui,Fan Xuelin,Li Dongfeng.Implementation of Modified Short-time Fourier Transform[J].Communications Technology,2017,50(5):1066-1068.(in Chinese)
[14]Carlson B D,Evans E D,Wilson S L.Search radar detection and track with the Hough transform,part I:System concept[J].IEEE Transaction on Aerospace and Electronic Systems,1994,30(1):102-108.
[15]刘健庄.一种高效的Hough变换实现方法[J].信号处理,1992,8(1):43-48.Liu Jianzhuang.An Efficient Implementation of the Hough Transform[J].Signal Processing,1992,8(1):43-48.(in Chinese)
[16]Peleg S,Porat B.The Cramer-Rao Lower Bound for Signals with Constant Amplitutude and Polynomial Phase[J].IEEE Trans.Signal Processing,1991,39(3):749-752.
[2]刘国情,袁俊泉,马晓岩,等.天基预警雷达自适应转换测量卡尔曼滤波[J].信号处理,2018,34(2):155-163.Liu Guoqing,Yuan Junquan,Ma Xiaoyan,et al.An Adaptive Converted Measurement Kalman Filtering Algorithm for Space-based Early Warning Radar[J].Journal of Signal Processing,2018,34(2):155-163.(in Chinese)
[3]贲德,林幼权.天基监视雷达[J].现代雷达,2005,27(4):1-4.Ben De,Ling Youquan.Space-based Surveillance Radar[J].Modern Radar,2005,27(4):1-4.(in Chinese)
[4]Huang Penghui,Liao Guisheng,Yang Zhiwei,et al.Approach for space-based radar manoeuvring target detection and high-order motion parameter estimation[J].IET Radar,Sonar and Navigation,2015,9(6):732-741.
[5]杨志伟,贺顺,吴孙勇.天基雷达高速微弱目标的积累检测[J].宇航学报,2011,32(1):109-114.Yang Zhiwei,He Shun,Wu Sunyong.A Long-Term Accumulated Detection Approach to High Speed Weak Target from Space-Borne Radars[J].Journal of Astronautics,2011,32(1):109-114.(in Chinese)
[6]李英祥,肖先赐.低信噪比下线性调频信号检测与参数估计[J].系统工程与电子技术,2002,24(8):43-45.Li Yingxiang,Xiao Xianci.Linear Frequency-Modulated Signal Detection and Parameter Estimation in Low Signalto-Noise Ratio Condition[J].Systems Engineering and E-lectronics,2002,24(8):43-45.(in Chinese)
[7]胥嘉佳,刘渝,邓振淼.LFM信号参数估计的牛顿迭代方法初始值研究[J].电子学报,2009,37(3):598-602.Xu Jiajia,Liu Yu,Deng Zhenmiao.The Starting Point Problem of Parameters Estimation for LFM Signal Based on Newton’s Method[J].Acta Electronica Sinica,2009,37(3):598-602.(in Chinese)
[8]Peleg S,Porat B.Linear FM signal parameter estimation from discrete-time observations[J].IEEE Trans on Aerospace and Electronic Systems,1991,27(7):607-615.
[9]贲德,龙伟军.天基雷达的关键技术[J].数据采集与处理,2013,28(4):391-396.Ben De,Long Weijun.Key Technology of Space-Based Radar[J].Data Acquisition and Processing,2013,28(4):391-396.(in Chinese)
[10]Fischman M A,Le C.Digital beamforming developments for the joint NASA/Air force space based radar[C]∥IEEE International Geoscience and Romote Sensing.Anchorage,AK:IEEE Press,2004:687-690.
[11]战立晓,汤子跃,朱振波.米波双基地雷达长时间相参积累算法[J].信号处理,2013,29(3):351-359.Zhan Lixiao,Tang Ziyue,Zhu Zhenbo.Long Term coherent Integration Algorithm for Metric Band Bistatic Radar[J].Journal of Signal Processing,2013,29(3):351-359.(in Chinese)
[12]张顺生,曾涛.基于keystone变换的微弱目标检测[J].电子学报,2005,33(9):1675-1678.Zhang Shunsheng,Zeng Tao.Weak Target Detection Based on Keystone Transform[J].Acta Electronica Sinica,2005,33(9):1675-1678.(in Chinese)
[13]张辉,范雪林,李东风.一种改进的短时傅里叶算法实现[J].通信技术,2017,50(5):1066-1068.Zhang Hui,Fan Xuelin,Li Dongfeng.Implementation of Modified Short-time Fourier Transform[J].Communications Technology,2017,50(5):1066-1068.(in Chinese)
[14]Carlson B D,Evans E D,Wilson S L.Search radar detection and track with the Hough transform,part I:System concept[J].IEEE Transaction on Aerospace and Electronic Systems,1994,30(1):102-108.
[15]刘健庄.一种高效的Hough变换实现方法[J].信号处理,1992,8(1):43-48.Liu Jianzhuang.An Efficient Implementation of the Hough Transform[J].Signal Processing,1992,8(1):43-48.(in Chinese)
[16]Peleg S,Porat B.The Cramer-Rao Lower Bound for Signals with Constant Amplitutude and Polynomial Phase[J].IEEE Trans.Signal Processing,1991,39(3):749-752.