基于STAP的机载雷达高速运动目标检测技术研究

针对机载雷达高速运动目标检测中存在严重的距离单元走动问题,将Keystone变换与STAP技术结合,提出了一种目标检测方法。该方法首先将雷达接收到的回波数据变换到频域,然后利用Keystone变换对目标的距离走动进行校正,再将校正后的数据变换回时域并做空时自适应处理（STAP）。仿真结果表明,该方法可有效克服高速运动目标距离走动导致STAP处理性能下降的问题,改善了目标检测性能。     

低信噪比下基于Keystone变换的多目标检测

在脉冲多普勒雷达里,针对低信噪比的多目标数据,该文提出了一种基于Keystone变换的运动补偿方案。利用Keystone变换校正由径向速度引起的线性距离走动,通过对所有脉冲的相干积累来提高信噪比。仿真实验结果表明,基于Keystone变换方法的性能优于传统相参积累的方法。     

基于Keystone变换的低信噪比ISAR成像

在ISAR成像中,当目标平稳飞行时,对于低信噪比的回波数据,常规的运动补偿方法不再适用,故提出一种基于Keystone变换的运动补偿方案,完成对低信噪比数据的处理. 利用Keystone变换校正由目标速度引起的线性距离走动,通过对相邻距离像相干积累以提高数据信噪比,进而引入相关法和PGA法完成对高次项运动的补偿. 仿真实验的结果表明,针对低信噪比数据的处理,基于Keystone变换的运动补偿方法优于传统的方法,从而有效地提高了成像雷达的作用距离.     

高速运动平台MIMO雷达“三跨”补偿研究

针对高速运动平台MIMO雷达地面动目标“三跨”运动及补偿的问题,建立空间模型,导出了回波时延和发射方向图随时间及周期变化的公式。分析了回波的特性,给出“三跨”走动的表达式,提出了用预补偿校正目标跨距离单元走动和跨波束走动,并结合分数阶傅里叶变换(FrFT)补偿目标跨多普勒单元走动的方法。该方法可以实现对目标“三跨”运动的同时补偿,且由于预补偿是对发射信号进行处理,其计算量远低于现有的补偿算法。最后用MIMO雷达稀布阵的思想,采用“稀疏发射紧凑接收”的方式进行跨波束走动及补偿的仿真,仿真结果证明了预补偿与FrFT相结合的补偿方法对于“三跨”走动补偿的有效性。     

带有距离走动和多普勒扩散的高速运动目标检测

针对运动目标在长时间积累过程中的距离走动和多普勒扩散问题,提出了一种基于多种方法相结合的高速多目标检测和参数估计方法.该方法利用楔形变换校正目标包络的距离走动,运用循环自相关函数法和"解线频调"法联合估计并补偿目标的二次相位,最后通过相参积累聚集能量来检测目标.所提方法有效地补偿了目标的距离走动和时变多普勒频率,延长了信号相干积累时间并提高了检测性能.该算法运算量小,适合于硬件实现.对算法的性能做了分析并进行了仿真,仿真结果验证了算法的有效性.     

基于Keystone-FRFT的机动弱目标检测算法

针对机动弱目标检测中出现的距离走动和多普勒频率走动问题,在分析回波信号走动的基础上,提出一种基于楔形变换和分数阶傅里叶变换的弱目标检测算法。算法使用楔形变换补偿距离走动,利用分数阶傅里叶变换补偿多普勒频率走动,在低信噪比情况下能有效地检测机动弱目标。仿真分析表明算法有效。     

基于GKT-RT-GDP的长时间相参积累算法

提出一种基于广义Keystone变换(generalized Keystone transform,GKT)、拉东变换(Radon transform,RT)和广义去调频处理(generalized dechirp process,GDP)的长时间相参积累算法,应用于对雷达高度表回波信号的处理。使用GKT校正由径向加速度引起的距离弯曲,应用RT估计雷达高度表的速度并构造补偿函数校正距离走动,采用GDP方法估计雷达高度表的径向加速度并构造相位补偿函数校正多普勒频率徙动,最后使用快速傅里叶变换对算法处理后的回波信号做相参积累。仿真结果表明,GKT-RT-GDP算法能够实现对多普勒频率徙动和距离徙动的校正,并且与基于KT-GDP长时间相参积累算法相比,在运算复杂度增加较小的条件下,相参积累后的信噪比增加了5 dB,算法的校正效果较好。     

一种新的高速多目标参数检测算法

该文提出一种新的高速、多目标窄带雷达目标检测和参数估计算法。首先采用基于循环平稳的联合Keystone变换与模糊数搜索方法完成目标运动参数粗估计,然后在粗估计基础上采用联合频域距离徙动补偿处理与分数阶傅里叶变换方法完成目标检测及参数估计。该算法适用于多目标及存在距离徙动、多普勒扩散和多普勒模糊的情况,其保持了循环平稳计算复杂度低的优点,且克服了已有循环平稳算法在工程应用中估计精度低和运动参数估计范围受限的缺陷。计算机仿真和实测数据验证了算法的有效性。     

大时宽带宽积信号匹配滤波研究

针对高速机动目标在观察时间内通常跨越多个距离单元,使得目标检测时进行能量相关积累变得困难的问题,对大时宽高速机动目标雷达回波信号进行了建模,分析了拉伸效应、加速度等因素对匹配滤波的影响．鉴于传统速度补偿仅补偿了多普勒损失而对跨距离损失未能有效补偿,提出了一种预失配速度补偿的新方法,解决了距离跨越情况下相参积累检测问题．通过仿真和实际数据分析,验证了该方法的有效性．     

相对运动多目标的逆合成孔径雷达成像

由于非合作的机动多目标相对于雷达射线的姿态是时变的,而且目标间可能存在相对运动,给逆合成孔径雷达(ISAR)成像造成较大的困难。当多目标间存在相对运动时,直接利用常规补偿方法通常得不到满意的结果。该文建立了目标相对运动的模型,分析了相对运动对成像的影响,提出了一种新的相对运动补偿算法。该算法对存在相对运动的目标在距离上利用Keystone变换进行分离,提取相对运动目标的回波,分别利用Autoclean算法进行运动补偿。模拟和实测数据的成像结果表明,该算法是可行的。     

临近空间慢速平台SAR地面动目标检测与成像

临近空间慢速平台SAR具有生存能力强、持续工作时间长、机动性能好等特点。该文提出了一种临近空间慢速平台SAR地面动目标检测与成像方法。由于平台运动速度较慢,地面静止杂波多普勒展宽较窄,有利于将地面杂波与动目标回波进行分离。首先利用多普勒滤波器实现地面动目标回波与静止杂波的分离,提取出动目标回波;然后将一阶Keystone变换与变分辨多普勒调频率估计方法相结合,在动目标速度未知的情况下完成距离走动校正和距离弯曲校正,解决了动目标回波距离徙动校正难的问题。利用估计出的多普勒调频率设计出方位压缩函数进行方位聚焦,从而完成动目标的检测与成像。该方法不仅适用于地面慢速运动目标,同时也适用于快速运动目标。计算机仿真验证了该方法的有效性。     

调频连续波激光探测系统多目标分辨方法研究

提出了一种基于速度补偿的距离-多普勒解耦方法,用于消除调频连续波激光探测系统探测高速目标时的速度模糊;提出了基于该解耦方法的调频连续波激光探测系统多目标分辨方法,使该系统能够在较大动态范围内分辨多个运动。仿真结果表明：基于速度补偿的距离-多普勒解耦方法可以扩展系统的测速范围,具有较高的测速和测距精度;多目标分辨方法可分辨高速运动的多个目标以及相同距离下不同速度的多个目标。     

Two dimension migration compensation method for W-band ISAR imaging

The problem of migration through the resolution cell (MTRC) in the W-band Inverse Synthetic Aperture radar (ISAR) imaging system is serious. Therefore, a novel two dimensional compensation method is proposed in this paper. Firstly, the cause of migration in ISAR imaging is analyzed. Then, the Keystone transform is used to compensate the MTRC in the range direction. After that, the minimum entropy algorithm is used to estimate the average rotate speed of the target and the rotate speed is used to compensate the cross range direction MTRC of a uniformly rotating target by using the phase correcting method. Finally, the sub-aperture imaging algorithm is used to reduce the cross range MTRC in imaging the maneuvering target. Simulation results show that a high resolution result is achieved and the effectiveness of the two dimensional compensation method is verified.     

Novel detection algorithm for high-speed maneuvering multi-target with narrowband radar

A novel detection method for the high-speed maneuvering multi-target with a constant acceleration is proposed. Firstly, velocity searching and Second-order Keystone Transform (SKT) are jointly applied to correct the range migration (RM). After the RM correction, the azimuth echoes can be considered as a Linear Frequency Modulation (LFM) signal. Secondly, Lv's Transform (LVT) is performed on the azimuth echoes, target energy will be accumulated into a sole peak in the Centroid Frequency (CF)-Chirp Rate (CR) domain, and an estimated acceleration can be obtained in terms of the peak's location in the CR-axis. Finally, according to the estimated acceleration, a compensation function is constructed to compensate the Doppler Frequency Migration (DFM), after that, the FFT is applied to accomplish coherent integration, and then target detection is carried out, meanwhile, the target's radial velocity can be estimated. Compared with the Radon-Fractional Fourier Transform (RFRFT), the proposed algorithm possesses the advantages of lower computational complexity and better anti-noise performance. The results of simulation and real data demonstrate the validity of the proposed algorithm.     

Generalized Keystone transform algorithm for dim moving target detection

Aimed at the problem that the accumulation result varies with the choice of the benchmark pulse used in the Keystone transform to correct range migration, a generalized Keystone transform algorithm is proposed for detecting the dim moving target via long-term coherent integration. The algorithm first searches for the minimum error of discrete time sampling and the corresponding pulse from digital pulse compression. Afterwards, this pulse echo is used as the benchmark in the Keystone transform, by which all the pulse echoes are corrected into the same range resolution cell. Accordingly, the maximum output after accumulation is obtained. Computer simulation and real data processing results are given to verify the effectiveness of the proposed method.     

Novel detection and parameters estimation of a high-speed multi-target

A novel algorithm for high-speed multi-target detection and parameters estimation with narrowband radar is proposed. Firstly, velocity and acceleration are roughly estimated with the combination of compensating range migration in the frequency domain and fractional Fourier transform. And then, based on the coarse estimation, keystone transform and fractional Fourier transform are employed to estimate the fold factor and acceleration accurately. In the case of multi-target, range migration, Doppler spread and velocity ambiguity, this algorithm is suitable, and the performance of the targets detection and parameters estimation is improved owing to the utilization of the coherent integration in a low signal-to-noise ratio. The computational load is greatly reduced by combination of coarse and accurate estimation. The validity of the proposed algorithm is demonstrated by computer simulation.