长时间相参积累是外辐射源雷达提高目标增益的主要方法。然而，在信号积累的过程中，由于外辐射源雷达双基构型下目标切向运动状态的影响，目标出现多普勒单元徙动，严重影响目标增益，降低目标探测距离。在外辐射源雷达双基构型的基础上，分析运动目标出现多普勒徙动问题成因，首次引入双频共轭算法。此方法使合成信号的等效波长大大增长，实现了多普勒二次项调频率趋于零，从而解决多普勒徙动问题。同时，提出压缩方位向信号重频的改进方式，进一步改善了双频共轭处理微弱目标的能力。该算法具有实现简单、计算量小，可应用于多目标场景的优势。仿真和实测数据表明，该算法可以解决运动目标检测中出现的多普勒徙动问题，提高目标信噪比。
Long-term coherent integration is a main method to improve gain in target identification for passive radar. However, tangential-speed leads to Doppler expansion based on bistatic model which decreases the gain and then degrades the detection range. In this work we discuss the contribution factor of Doppler migration and propose an algorithm to deal with Doppler migration based on sub-band double carrier frequency conjugated processing (SDCFCP). SDCFCP increases the equivalent wavelength of composite signal, makes Doppler quadratic term close to zero, and solves the Doppler migration problem. We also propose an improved method to decrease PRF at azimuth and enhance the weak target detection ability. SDCFCP can be applied conveniently with little calculation work. Moreover, the algorithm is useful on multi-target scenario. Finally, experiments based on simulated and real signals verify the proposed algorithm.
[1] Griffiths H. Developments in bistatic and networked radar[C]//Radar(Radar), 2011 IEEE CIE International Conference on Radar,2011,1:10-13.
[2] Griffiths H D, Baker C J. Passive coherent location radar systems. Part 1:performance prediction[J].IEE Proceedings-Radar Sonar & Navigation,2005,152(3):153-159.
[3] Howland P. Editorial:passive radar systems[J]. IEE Proceedings-Radar Sonar and Navigation,2005,152(3):105-106.
[4] 陶然, 王越, 单涛, 等. 分布式无源检测信息系统研究进展[J]. 深圳大学学报(理工版), 2004,21(2):101-106.
[5] 关欣, 胡东辉, 仲利华, 等. 一种高效的外辐射源雷达高径向速度目标实时检测方法[J]. 电子与信息学报,2013,35(3):581-588.
[6] 杨金禄, 单涛, 陶然. 数字电视辐射源雷达的相参积累徙动补偿方法[J].电子与信息学报, 2011,33(2):407-411.
[7] 关欣, 仲利华, 胡东辉, 等. 一种基于RSPWVD-Hough变换的无源雷达多普勒展宽补偿方法[J]. 雷达学报, 2013,2(4):430-438.
[8] 庞存锁. 基于离散多项式相位变换和分数阶傅里叶变换的加速目标检测算法[J]. 电子学报, 2012,40(1):184-188.
[9] Hoshino T, Suwa K, Nakamura S, et al. Long-time integration by short-time cross-correlation and two-step Doppler processing for Passive Bistatic Radar[C]//Radar Conference,2013, 1552(1):451-454.
[10] Liu Y, Xing M, Guo R, et al. Sandglass transformation for synthetic aperture radar detection and imaging of ship at low signal-to-clutter-plus-noise ratio[J]. Iet Radar Sonar Navigation, 2011,5(3):361-373.
[11] 战立晓, 汤子跃, 朱振波. 一种米波相控阵雷达四代机目标检测算法[J]. 电子与信息学报, 2013,35(5):1163-1169.
[12] Jian-Fen Y, Dao-Jing L, Li-Bo T, et al. Detection and imaging of aerial moving targets based on spaceborne SAR[C]//International Conference on Radar,2006:1-5.
