基于松弛半定规划零速滤波器的杂波图检测方法

零速滤波器性能的好坏会影响杂波图的建立与检测效果,传统零速滤波器是采用快速傅里叶变换(Fast Fourier Transform,FFT)滤波器来实现的,其主瓣宽度固定,不能根据杂波谱宽灵活调整,且相邻滤波器间存在交叠损失,影响杂波图的检测性能.鉴于此,本文提出一种基于松弛半定规划的零速滤波器设计方法,该方法可以根据...     

局部熵算法在机载PD雷达杂波跟踪中的应用

本文介绍一种用于机载PD雷达的杂波跟踪技术,结合机载PD雷达杂波分布特征和局部熵算法的特点,将局部熵算法用于杂波跟踪,提出一种最大局部熵相似性判决准则对经过局部熵滤波后的仿真数据进行分割处理;将局部熵滤波与K邻域滤波结合,构成混合型滤波器,经仿真实验,得到了满意的杂波边缘提取结果.     

一种双极化气象雷达自适应谱极化滤波方法

针对双极化气象雷达中非气象回波的滤除问题,该文提出一种基于詹森-香农散度原理的自适应移动谱去极化比(AMsDR)滤波方法。该方法根据不同方位向回波的谱去极化比分布情况,利用气象回波和杂波在距离-多普勒图上的特征差异实现气象回波的保留和杂波的滤除。与现有固定阈值的移动谱去极化比滤波器相比,AMsDR滤波方法可根据不同方位向降雨和杂波的回波差异自适应地选择滤波阈值,提高杂波抑制与降雨保留性能。      

PD中重频下主瓣杂波特性及抑制滤波器设计

针对中重频PD雷达应用背景,设计了一种主瓣杂波抑制滤波器。对主瓣杂波在实际情况下的参数特点进行了详细分析,得出杂波强度、带宽和功率与俯仰角的对应关系,据此提出了采用查表法设计主瓣杂波抑制滤波器方法;该方法克服了对消器和AMTI滤波器的不足,能有效改善杂波抑制性能,其算法存储容量和实时性满足设计要求,具有良好的工程应用价值。     

杂波抑制的分形处理:小波-多尺度自适应Kalman滤波

从杂波分形模型的角度,以基于小波变换和多尺度自适应Kalman滤波的方法,解决雷达信号处理中重要的杂波抑制问题。首先对接收信号作小波分解,利用小波系数建立状态方程和观测方程,用Kalman滤波对每一尺度估计分形杂波,然后从接收信号中减去估计得到的分形杂波,从而实现杂波抑制。仿真结果表明,基于小波变换和多尺度Kalman滤波的处理方法,能对分形杂波进行有效的估计分析,进而实现有效的抑制。     

基于回归滤波器的地杂波抑制研究

本文研究了基于正交多项式拟合的回归滤波器。由于地物杂波变化缓慢,将输入信号投影到低阶多项式子空间可以很好的拟合地物杂波,进而形成一个在零频附近的带凹槽的高通滤波器。回归滤波器的频率响应仅和对信号的采样点数与正交多项式最大阶的阶数有关,通过仿真,回归滤波器对零频附近的地物杂波有明显的抑制效果,且其抑制性能优于五阶的IIR椭圆滤波器。     

战场侦察雷达杂波对消技术

为了进一步改善战场侦察雷达对杂波的抑制能力,通过对递归与非递归动目标显示(MTI)滤波器的性能研究,总结了零级点对MTI滤波器性能的影响。结合战场侦察雷达的特性,设计了3种MTI滤波器模型。通过仿真分析其频谱特性和改善因子,结果表明,在不同的杂波背景下,选择设计相应的MTI滤波器,能够有效抑制杂波,并能得到较大的改善因子。     

子空间干扰非高斯杂波的抑制

在复杂电磁环境下,往往需要在线估计杂波协方差矩阵,从而自适应调整滤波器权值,实现对杂波的有效抑制,这样有利于目标的估计、检测、定位或跟踪。该文考虑非高斯杂波模型,且部分杂波受到子空间信号干扰,并且有用信号也位于该子空间内。常规方法会导致自适应滤波器在目标多普勒频率处有较大的衰减,极大影响了有用信号的探测。为此提出了一种知识辅助的分层贝叶斯模型,采用变分贝叶斯推断方法获得杂波协方差矩阵的近似后验分布,利用后验均值设计杂波抑制滤波器,可以有效提高目标的探测性能。计算机仿真和实测数据验证结果表明,该方法能够有效抑制杂波,而在目标处有较好的探测能力。      

复杂海杂波背景下分数低阶匹配滤波检测方法

针对在复杂海杂波背景下,雷达目标检测中动目标检测(Moving Target Detection,MTD)技术的检测性能显著下降的问题,以及局部最优检测器(Locally Optimum Detector,LOD)仅适用于低信杂比背景下弱目标检测的问题,基于分数低阶统计量理论,提出了一种分数低阶匹配滤波检测方法.该方法通过幂变换抑制杂波的非高斯特性,通过应用杂波分数低阶协方差矩阵特征值分解的方法白化相关杂波,在此基础上应用匹配滤波进行目标积累,以提高信杂比.通过仿真和实测数据,对所提出方法的检测性能进行了验证,并且与MTD和LOD进行了比较.结果表明,本文所提出方法能较好地解决非高斯相关杂波背景下的目标检测问题,检测性能明显优于MTD和LOD方法.     

自适应杂波抑制技术在雷达中的应用

动目标显示(MTI)技术是雷达在杂波环境中发现运动目标的有效手段。首先讨论了雷达信号处理中常用的自适应动目标显示技术,即在多杂波环境下的自适应杂波抑制技术。然后针对雷达杂波抑制中常用的级联MTI滤波器,提出了一种新的设计方法,即采用时变加权原理,通过对动杂波速度估值,实现对运动杂波抑制滤波器权值的优化。最后给出了这2种杂波抑制级联型MTI的工程实现。     

MTI detection loss in clutter

The detection performance of a nonrecursive quadrature-channel MTI filter in Rayleigh and log-normal clutter is examined from a detection loss viewpoint. A formula is provided for detection loss in Rayleigh clutter whereas curves are provided for typical situations in log-normal clutter.     

Clairvoyant and adaptive signal detection in non-Gaussian clutter:a data-dependent threshold interpretation

This paper addresses the problem of signal detection in correlated non-Gaussian clutter modeled as a spherically invariant random process. The optimum strategy to detect a constant signal, with either known or unknown complex amplitude, embedded in correlated Gaussian clutter is given by comparing the whitening-matched filter output with a fixed threshold. When the clutter is non-Gaussian, the performance of the matched filter sensibly degrades. The optimum strategy is the classical whitening-matched filter output compared with a data-dependent threshold. This interpretation provides a deeper insight into the structure of the optimum detector and allows us to single out a family of suboptimum detectors based on a polynomial approximation of the data-dependent threshold. They are easy to implement and have performance that is really close to the optimal. The adaptive implementation of the polynomial detectors is also investigated, and their performance is analyzed by means of Monte Carlo simulation for various clutter scenarios     

基于双门限控制的机载气象雷达地杂波抑制方法

针对机载气象雷达工作于风切变模式时的地杂波抑制问题,该文提出了一种双门限控制的自适应地杂波抑制方法。该方法在有效估计杂波谱中心和谱宽的基础上,利用每个距离单元的回波功率信息设计双门限控制的自适应凹口滤波器,在最大程度上滤除地杂波的同时,减小杂波残余对风切变信号的影响。仿真结果表明,该方法具有良好的杂波抑制效果,并能有效地提高风切变信号风速估计的准确性。      

高频地波雷达电离层杂波的空域极化域协同抑制方法

高频地波雷达（High Frequency Surface Wave Radar,HFSWR）能够探测视距外的海上目标和超低空飞行器,但其性能通常被电离层杂波严重影响。该文使用一种空域极化域协同滤波算法用于电离层杂波抑制。针对其中电离层杂波空域和极化域参数的估计问题,在距离-多普勒域上利用基于压缩感知（Compressive Sensing,CS）的DOA测角方法进行空域参数估计,并提出一种基于统计特性的极化参数估计方法完成极化参数估计。这两种估计方法可获得更高的参数估计精度,从而提高了电离层杂波空域极化域抑制方法的性能。某HFSWR系统实测数据处理结果表明了参数估计和电离层杂波抑制方法的有效性。      

未知杂波条件下样本集校正的势估计概率假设密度滤波算法

在贝叶斯框架下的多目标跟踪算法中,总是假设杂波的先验信息是已知的。然而,实际应用中,杂波分布一般是未知的,假设的杂波分布往往与实际情况匹配度差,难以保证滤波精度。针对该问题,该文研究了未知杂波势估计概率假设密度(CPHD)滤波算法。首先,提出一种基于狄利克雷过程混合模型(DPMM)类的未知杂波CPHD算法,该算法能够自动选取合适的类数对杂波进行描述,有效降低了杂波空间分布估计的误差。此外,提出样本集校正的思想,并将其引入所提算法,通过去除样本集中由真实目标产生的量测,较好地解决了杂波数过估和目标数低估的问题。与传统算法相比,所提算法的滤波精度更接近于杂波信息匹配情况下的性能,仿真结果验证了其优越性与鲁棒性。     

Optimum radar signal processing in clutter

This paper considers the joint optimization of a class of radar signals and filters in a number of clutter-pins-noise environments. The radar signal processor in this case will be optimum in the sense that its output at the time of target detection yields the maximum ratio of peak signal power to total interference power. If the interference at the input to this signal processor is a Gaussian random process, this processor also yields the maximum probability of detection for a given value of false-alarm probability. The signals used are pulse trains and the filters are tapped delay lines. The purpose of signal design is to determine the optimum complex weighting for each pulse of the pulse train. Filter design yields the optimum complex weighting for the output taps of the delay line. Filter design for a specified signal is considered first. This is followed by combined signal and filter design and matched filter design. Constrained signal and filter design is investigated last. It should be emphasized that the optimizations require a knowledge of the clutter time-frequency distribution. For practical situations, when the clutter distribution is unknown, an adaptive filter is proposed that automatically provides the optimum filter weights for a given transmitted signal. When the clutter has a range-time extent less than the equivalent range-time extent of the signal, filter design alone yields nearly optimum performance. As the clutter becomes extended in range-time, it is necessary to consider jointly the design of signal and filter to obtain an optimum radar signal processor. In this report it is suggested that the signal be designed under the assumption of the clutter being extended over a broad range of Dopplers and that the signal processor consist of a bank of adaptive filters. Then each filter output yields the maximum ratio of peak signal to total interference power for this signal design.     

一种稳健的两维两脉冲杂波相消方法

两维两脉冲杂波对消方法,可以有效地杂波迹进行杂波预滤波,进一步提高后续空时自适应算法的动目标检测性能。但在实际中不准确的载机速度和偏航角等雷达系统参数信息,会制约其杂波抑制性能。为了解决这一问题,文中提出了一种稳健的两维两脉冲杂波相消方法,该方法进一步将载机速度和偏航角误差作为先验知识加入到滤波器系数矩阵设计中,提高了TDPC在雷达系统参数存在误差时的稳健性。并分别利用仿真数据和MCARM实测数据进行了验证。实验结果表明,在载机速度和偏航角存在误差的情况下,相比较TDPC,RTDPC能更加有效地对消杂波,改善了后续空时自适应算法的动目标检测性能。     

一种高频雷达流星余迹回波干扰消除方法

流星余迹回波是高频雷达的主要干扰源之一,严重影响了雷达对目标的探测性能,必须加以抑制。该文根据地海杂波与流星干扰在多普勒谱上的差别,提出了用FIR型高通滤波器滤除杂波使流星干扰凸显出来;再根据流星干扰的分布特点分段计算背景噪声均值,求取流星干扰检测门限;最后用杂波信号来插值流星干扰位置上的数据,消除因去除干扰造成的杂波相位不连续。实测数据处理表明,该文方法工程实现性强,效果良好。     

时变级联滤波器的两种设计方法

本文针对雷达杂波抑制中常用的时变级联滤波器,提出了两种实用的设计方法。第一种方法通过时变级联滤波器与时变非级联滤波器的等效来设计时变级联滤波器。该方法可以使时变级联滤波器具有最佳杂波滤波器的效果。第二种方法通过对总的等效滤波器的设计来得到级联滤波器第二级的权系数。分析表明,时变级联滤波器第二级的频率响应很难写出,但可以通过总的等效频率响应来体现。     

Wideband Extended Range-Doppler Imaging and Waveform Design in the Presence of Clutter and Noise

This paper presents a group-theoretic approach to address the wideband extended range-Doppler target imaging and design of clutter rejecting waveforms. An exact imaging method based on the inverse Fourier transform of the affine group is presented. A Wiener filter is designed in the affine group Fourier transform domain to minimize wideband clutter range-Doppler reflectivity. The Wiener filter is then used to form an operator to precondition transmitted waveforms to reject clutter. Alternatively, the imaging and clutter rejection methods are equivalently re-expressed to perform clutter suppression upon reception. These methods are coupled with noise suppression upon reception. Numerical simulations are performed to demonstrate the performance of the proposed approach. Our study shows that the framework introduced in this paper can address the joint design of receive and transmit processing, design of clutter rejecting waveforms, suppression of noise, and reduction of computational complexity in receive processing