改进的CS-UKF加速度方差自适应跟踪算法

针对基于当前统计模型的状态噪声协方差阵中的加速度方差调整方法对一般机动目标、非机动目标跟踪精度差的问题,研究其改进方法;在建立机动目标当前统计模型离散状态方程和雷达导引头离散观测方程的基础上;利用雷达导引头测量信息和位置预测值之间的扰动对加速度方差进行调整,提出了改进的加速度方差自适应调整无迹卡尔曼滤波跟踪算法;数字仿真验证了该算法对非机动目标、一般机动目标以及高机动目标均具有良好的跟踪效果。     

角闪烁噪声测量条件下的剩余飞行时间估计

针对雷达导引头角闪烁噪声测量条件下的机动目标,研究剩余飞行时间计算方法。建立了闪烁噪声计算模型;在粒子滤波算法和扩展卡尔曼滤波算法的基础上,推导了扩展卡尔曼粒子滤波算法的实现过程;根据估计结果建立了剩余飞行时间计算模型,在剩余飞行时间表达式中考虑了目标机动加速度的影响。仿真结果表明,基于机动目标当前统计模型的扩展卡尔曼粒子滤波算法对闪烁噪声测量条件下的机动目标具有良好的跟踪性能,对剩余飞行时间具有较高的估计精度。     

一种基于时频分析的逆合成孔径声呐的距离-瞬时多普勒成像方法

传统距离－多普勒逆合成孔径成像方法是基于匀速转动的目标模型之上的,然而当目标机动时,由于目标各散射点多普勒效应的差异及投影平面的变化,距离－多普勒成像可能会失效。本文运用时频分析的方法,提出了一种新的距离－瞬时多普勒成像的方法,改善了原方法对机动目标的成像效果。实测的结果表明了该方法行之有效。     

基于GPU的高性能并行计算技术

针对NVIDIA CUDA(Compute Unified Device Architecture)架构的第三代GPU高性能计算技术开展了研究,利用具有448个处理核心的NVIDIA GPU GTX470实现了脉冲压缩雷达的基本数据处理算法,包括脉冲压缩算法与相参积累算法。根据GPU的并行处理架构,将脉冲压缩、相参积累完成了并行算法优化设计,有效的将算法映射到GPU GTX470的448个处理核心中,完成了脉冲压缩雷达基本处理算法的GPU并行处理实现,并针对处理结果效果与实时性进行了评估。     

脉间二相编码雷达高度表信号处理器

脉问二相编码信号不仅满足脉冲多普勒雷达高度表的要求，而且在频域和时域具有较高的分辨率和测量精度，同时能够解决测距和测速模糊。除此之外，距离旁瓣和多普勒旁瓣亦可有效抑制。然而，脉间二相编码和传统的二相编码信号一样，该信号仍属于多普勒敏感信号。要实现对该类信号的匹配处理必须进行多普勒补偿。基于频域滤波、相干积累与相位补偿的一致性原理可采用图1的处理方法。     

机载测量雷达航路规划分析

在巡航导弹试验时,为了保证机载雷达测量数据的连续性,需要对飞机航路进行规划,来保证被探测目标处于雷达威力范围内且不出现盲速;基于数字阵列雷达体制,采用进化算法对载机航路进行规划,本研究着重解决机载共形天线由于平台,导致测量雷达方位角范围减少而对测量雷达的约束限制,采用不同的代价函数对载机的航路进行优化,并统计对比了数字阵列(DAM)和模拟阵列(SAM)两种体制盲速时间。     

机载光电观瞄系统的瞄准线指向线性运动补偿方法

为方便操作员快速捕捉并瞄准目标,提出一种适用于机载光电观瞄系统的线性运动补偿方法。该方法借助地面目标相对载机在初始东北天坐标系下的速度矢量进行分解,得出目标相对光电系统在惯性坐标下的角速度,并根据解算出的角速度值实时进行伺服补偿,驱动光电转塔于手动模式下,当操作员不操控光电转塔时,系统的瞄准线能够自动地指向地面目标区域。该方法已在某型无人机用光电观瞄系统挂飞试验中进行了验证,结果表明:在电视观瞄具的小视场（0.70.5）下,地面目标点、瞄准线指向点相对载机点的张角在方位和俯仰方向均小于该视场的1/6。     

机动目标逆合成孔径激光雷达成像算法

针对逆合成孔径激光雷达对机动目标成像时,其回波信号存在距离向色散和方位向多普勒时变的问题,在建立机动目标精确回波信号模型的基础上,提出一种基于积分立方次相位函数-分数阶傅里叶变换的成像算法.在距离压缩时,首先采用积分立方次相位函数快速估计出回波脉冲的调频率,进而在最佳旋转角下采用分数阶傅里叶变换实现距离像压缩,消除距离色散.经过运动补偿后,在方位压缩时结合积分立方次相位函数-分数阶傅里叶变换与Clean技术实现对每一距离单元上强弱散射点的分离成像,解决由于机动运动产生的方位多普勒时变而形成的图像散焦问题.最后,通过散射点模型的仿真实验,验证了所提方法的有效性.     

多普勒加速度测量的数字相关鉴相算法

针对激光多普勒加速度测量系统信号信噪比较差的问题,提出了一种采用数字相关鉴相算法进行加速度解调的方法。使用数字相关鉴相算法计算激光多普勒加速度测量系统中两路干涉信号的相位差,再由相位差的变化率来计算目标加速度,从而实现运动物体加速度的连续测量。仿真结果表明:该算法在信噪比为20dB时,加速度测量的误差为0.135m/s~2,分辨率为7.3×10~(-3) m/s~2。搭建了激光多普勒加速度测量系统,对压电陶瓷振荡器的加速度进行测量,加速度的测量误差为0.13m/s~2。测量结果表明,该算法能够有效减少随机噪声的干扰,提高加速度的测量精度。     

一种基于多普勒频移的被动合成孔径声纳探测方法*

由于自主小平台声纳孔径有限,对声纳探测的分辨率的提高有所限制。小平台的机动可以有效的与声纳探测方法相结合来提高声纳探测性能。针对这一特点,提出一种基于多普勒频移技术的被动合成孔径声纳探测方法。该方法根据自主小平台的机动所引起声纳的接收信号多普勒频移的变化,进行目标的频率与方位联合估计。本文将自主小平台的机动引入到波束形成技术当中形成一种新的被动合成孔径技术。数值仿真表明,该方法可以有效的进行目标方位估计,并且获得较高的方位分辨率,改善了自主小平台的探测性能。     

Estimating the instantaneous velocity of randomly moving target swarms in a stratified ocean waveguide by Doppler analysis

Doppler analysis has been extensively used in active radar and sonar sensing to estimate the speed and direction of a single target within an imaging system resolution cell following deterministic theory. For target swarms, such as fish and plankton in the ocean, and raindrops, birds and bats in the atmosphere, multiple randomly moving targets typically occupy a single resolution cell, making single-target theory inadequate. Here, a method is developed for simultaneously estimating the instantaneous mean velocity and position of a group of randomly moving targets within a resolution cell, as well as the respective standard deviations across the group by Doppler analysis in free-space and in a stratified ocean waveguide. While the variance of the field scattered from the swarm is shown to typically dominate over the mean in the range-velocity ambiguity function, cross-spectral coherence remains and maintains high Doppler velocity and position resolution even for coherent signal processing algorithms such as the matched filter. For pseudo-random signals, the mean and variance of the swarms' velocity and position can be expressed in terms of the first two moments of the measured range-velocity ambiguity function. This is shown analytically for free-space and with Monte-Carlo simulations for an ocean waveguide.     

任意复包络信号的匀速运动目标回波脉间补偿及相干积累

现代声呐、水下制导等水声探测系统常常使用窄带脉冲、调制、编码、伪随机等种类繁多的发射信号波形来满足低信噪比检测、高分辨估计、抗干扰、主动隐蔽探测的应用需求.针对这一情况,本文研究了任意信号的长时间积累问题,给出了一种任意复包络信号的匀速运动目标回波脉间补偿及相干积累检测方法.通过构建任意发射信号波形的广义模糊函数,将匹配滤波器输出表示为所构造的广义模糊函数,使得任意复包络信号的脉压波形不仅能够用统一的数学模型来表述和计算,而且能够提供多脉冲回波的距离走动信息和多普勒频移信息,为多脉冲距离位置对齐和Fourier变换(FFT)积累提供了依据.对于用广义模糊函数表示的匹配滤波器输出,采用Keystone变换将复包络对齐,消除了距离走动,采用FFT补偿多普勒频移项,实现了任意复包络信号的长时间相干积累.对于水下探测中使用的连续波信号、线性调频信号以及复杂的m序列编码信号、Costas跳频编码信号波形进行了信号积累及检测的计算机仿真,验证了任意复包络信号的匀速运动目标回波脉间补偿及相干积累的正确性.消声水池实验验证了该方法的有效性.     

Single-frequency mid-infrared optical parametric oscillator source for coherent laser radar

We report on the design and characterization of a highly coherent mid-IR source at 3.57mum based on a single-frequency optical parametric oscillator. Detailed frequency and amplitude noise spectra have been measured. The rms intensity noise from 1.2 to 1000 Hz was 0.03%, and a rms frequency drift of 8 kHz in 1 ms was observed. We have also demonstrated the utility of this source for coherent laser radar applications by measuring micro-Doppler spectra from vibrating targets.     

High resolution inverse synthetic aperture radar imaging of three-axis-stabilized space target by exploiting orbital and sparse priors

The development of inverse synthetic aperture radar(ISAR) imaging techniques is of notable significance for monitoring, tracking and identifying space targets in orbit. Usually, a well-focused ISAR image of a space target can be obtained in a deliberately selected imaging segment in which the target moves with only uniform planar rotation. However, in some imaging segments, the nonlinear range migration through resolution cells(MTRCs) and time-varying Doppler caused by the three-dimensional rotation of the target would degrade the ISAR imaging performance, and it is troublesome to realize accurate motion compensation with conventional methods. Especially in the case of low signal-to-noise ratio(SNR),the estimation of motion parameters is more difficult. In this paper, a novel algorithm for high-resolution ISAR imaging of a space target by using its precise ephemeris and orbital motion model is proposed. The innovative contributions are as follows. 1) The change of a scatterer projection position is described with the spatial-variant angles of imaging plane calculated based on the orbital motion model of the three-axis-stabilized space target. 2) A correction method of MTRC in slant-and cross-range dimensions for arbitrarily imaging segment is proposed. 3) Coarse compensation for translational motion using the precise ephemeris and the fine compensation for residual phase errors by using sparsity-driven autofocus method are introduced to achieve a high-resolution ISAR image. Simulation results confirm the effectiveness of the proposed method.     

空时多普勒频移域运动小目标的抗干扰探测方法

有源声呐使用多普勒敏感信号可在多普勒频移域分离杂波、混响等干扰和运动目标,但低信干比时强干扰的时间旁瓣泄露和多普勒旁瓣泄露会淹没弱目标.针对该问题,提出了一种基于自适应最小均方(LMS)算法和宽带模糊函数(WAF)的运动小目标抗干扰探测方法.首先在空间多普勒频移域上利用基于LMS的自适应陷波器抑制干扰,然后在快时间多普...     

旋转双阵元水下目标定向方法

提出一种旋转双阵元的水下目标定向方法,通过旋转双阵元,主动产生目标到达信号的多普勒效应,结合目标声波信号到达时间差,联合利用时间差和多普勒信息对目标进行定向.通过目标函数的设定,使得两路信号经过延时和伸缩后达到最佳匹配所对应的方向即为目标方向.仿真结果表明,在设定的场景下,本文提出的方法对于各个方向的目标均有良好的定向效果,对于1000m的目标平均定向角度误差小于1°;相对于双阵元到达时间差方法,具有更好的精度和鲁棒性。实验结果验证了旋转双阵元定向方法在实际应用中的有效性.      

Three-dimensional coherent ladar based on FMCW and its flight demonstration

A scanning three-dimensional coherent laser radar(ladar) based on the frequency modulated continuous wave(FMCW) is proposed and demonstrated, which can obtain many three-dimensional high-quality images. The system utilizes an electro-optic modulator and an optical filter to output a linear FMCW with a bandwidth of2 GHz. The flexible and variable rotating double prism is used for beam scanning. The images of flight demonstration are formed by attitude compensation correction. The experiment result validates the performance of our system for airborne three-dimensional scanning imaging.     

固体相干成像激光雷达实验

采用单块非平面环形激光器的本地振荡器、种子注入高重复频率Q开关Nd∶YAG激光器的功率振荡器、振镜扫描偏转和光学接收装置、控制和显示等部件构成固体相干成像激光雷达实验装置.利用该装置对目标进行了距离成像和速度测量实验.在图像分辨力为64×64时,获得了成像速度为8 fps的目标距离图像.速度测量平均误差为6%.     

Chaotic system for self-synchronizing Doppler measurement

In a radar system, it is necessary to measure both range and velocity of a target. The movement of the target causes a Doppler shift of the radar signal, and the size of the Doppler shift is used to measure the velocity of the target. In this work, a chaotic drive-response system is simulated that detects a Doppler shift in a chaotic signal. The response system can detect Doppler shifts in more than one signal at a time.     

Radar Measurements of the Vibration Amplitude

Technical Physics - We propose a method for measuring the harmonic vibration amplitude of a reflector using a coherent radar station. A mathematical model describing the dependence of the Doppler...