线性调频信号匹配滤波器的研究与仿真

对雷达系统中普遍使用的线性调频信号进行时域频域分析,介绍了线性调频信号匹配滤波器的时频特性,重点计算和分析了此类信号经匹配滤波压缩处理的过程和结果,最后对线性调频信号匹配滤波器输出过程进行建模,分析了雷达目标回波信号的接收方法以及经过匹配滤波器后的输出结果。     

针对线性调频雷达系统的信源数估计算法

针对线性调频体制雷达系统,提出了一种基于匹配滤波的快速估计雷达及诱饵数量的方法。首先从雷达和诱饵信号前沿、信号后沿的脉内信息中获取线性调频信号的调频斜率,然后构造匹配函数,采用匹配函数对混合信号进行匹配滤波,最后对滤波后的信号进行搜峰处理,得到雷达与诱饵的数量和。相比于谱估计信源数估计,本方法不受导引头频段、口径的限制,不受弹目距影响,也不受接收处理通道数限制。在小口径、远距离条件下,也能识别低频段雷达诱饵的数量。     

线性调频信号主瓣不展宽旁瓣抑制方法

以汉明窗为代表的加权方法在抑制线性调频信号的匹配滤波输出峰值旁瓣的同时展宽主瓣,致使距离分辨力下降。为兼顾旁瓣抑制和高距离分辨力的需求,该文提出一种新的主瓣不展宽旁瓣抑制方法。该方法首先将匹配滤波和加权处理的输出幅度进行归一化处理,然后逐点进行比较,再取各点对应的最小值作为最终的输出数据。该方法兼取了匹配滤波和加权处理的优点,其-3 dB主瓣展宽系数与匹配滤波相比仅为1,而旁瓣抑制性能和对应的加权处理相当。仿真结果和湖上试验验证了该方法的有效性。     

毫米波雷达直升机旋翼回波匹配滤波研究

针对低重频毫米波雷达直升机旋翼回波信号检测中旋翼回波信噪比低的问题,本文采用发射大时宽带宽的线性调频信号,接收匹配滤波处理以增加旋翼回波信号的信噪比,并推导了线性调频旋翼回波模型。由于旋翼旋转对雷达回波产生调幅效应,使其对线性调频匹配滤波器失配,造成信噪比的下降。本文利用匹配滤波的概念,用旋翼匹配滤波器组近似达到了旋翼匹配滤波的性能,提高后端旋翼回波检测的信噪比。     

一种低时间旁瓣电平,高多普勒容限的脉压信号波形综合及其处理方法

本文针对某雷达的要求,寻到了一种时间旁瓣电平低、多普勒容限高的脉冲压缩信号－截断高斯窗非线性调频（ＮＬＦＭ）信号,介绍了此信号波形的综合方法,为进一步提高脉压性能,给出了修正型匹配滤波处理方法,并给出了此种信号在小脉压比时经匹配滤波和修正型匹配滤波处理后脉压性能的计算机仿真结果。     

线性调频信号数字脉冲压缩技术分析

在线性调频信号脉冲压缩原理的基础上,利用Matlab对数字脉冲压缩算法进行仿真,得到了雷达目标回波信号经过脉冲压缩后的仿真结果。运用数字脉冲压缩处理中的中频采样技术与匹配滤波算法,对中频采样滤波器进行了优化,降低了实现复杂度,减少了运算量与存储量。最后总结了匹配滤波的时域与频域实现方法,得出在频域实现数字脉冲压缩方便,运算量小,更适合线性调频信号。     

脉冲压缩器件及其进展

在脉冲压缩雷达中,线性调频和非线性调频信号的产生和匹配滤波,传统地使用表面声波器件。若采用数字信号产生器,则无论是波形综合还是误差校正,均可获得极大的灵活性。     

线性调频信号特征分析及其在现代雷达中的应用

简要介绍现代雷达的发展过程,给出线性词频信号的时域和频域特点,重点计算和分析了此类信号经匹配滤波压缩处理的过程和结果,最后介绍了线性调频信号产生方法和压缩处理方法,以及几种典型应用。     

动目标合成孔径雷达成象的二次相位匹配滤波法

本文针对合成孔径雷达运动目标回波的特点,引入多普勒调频率匹配滤波方法,解决由于运动目标成像二次相位失配而引起的方位散焦问题,提出了一种适合快速处理的离线式的匹配矩阵结构,计算机模拟得到运动目标聚焦良好的图象。     

单个线性调频脉冲信号测速方法之研究

对单个线性调频脉冲信号测速进行了研究，分析了线性调频脉冲信号的处理过程，得到匹配滤波输出信号的峰值幅度模型，提出利用双通道数字滤波器实现单个脉冲测速的方法，并给出了利用匹配滤波输出信号的幅度信息计算多普勒频移和目标速度的表达式，最后通过数字视频信号仿真证明了该方法的正确性。     

X-ray fluoroscopy spatio-temporal filtering with object detection

One potential way to reduce patient and staff X-ray fluoroscopy dose is to reduce the quantum exposure to the detector and compensate the additional noise with digital filtering. A new filtering method, spatio-temporal filtering with object detection, is described that reduces noise while minimizing motion and spatial blur. As compared to some conventional motion-detection filtering schemes, this object-detection method incorporates additional a priori knowledge of image content; i.e. much of the motion occurs in isolated long thin objects (catheters, guide wires, etc.). We create object-likelihood images and use these to control spatial and recursive temporal filtering such as to reduce blurring the objects of interest. We use automatically computed receiver operating characteristic (ROC) curves to optimize the object-likelihood enhancement method and determine that oriented matched filter kernels with 4 orientations are appropriate. The matched filter kernels are simple projected cylinders. We demonstrate the method on several representative X-ray fluoroscopy sequences to which noise is added to simulate very low dose acquisitions. With processing, we find that noise variance is significantly reduced with slightly less noise reduction near moving objects. We estimate an effective exposure reduction greater than 80%     

基于极化变换的极化匹配滤波器及其通带理论

借助极化基变换思想,通过矩阵特征值与特征矢量的方法求取了部分极化情况下极化匹配滤波器的极化天线最优接收极化方式,即最优极化Jones矢量解。分析了极化白化滤波器与匹配滤波器的性能差异,提出了极化白化-匹配联合滤波方法。针对极化匹配滤波器,分析了其最优极化接收Jones矢量在极化复平面上的表征。并在极化复平面上分析了极化通带的特性,得出在poincaré球上的极化球冠的通带映射到极化复平面变化为极化圆的表征模式,给出了极化圆随通带大小变化的趋势,这是极化通带理论的一个新发展,为极化滤波创造了简便的判决方法,同时为极化滤波中的数据处理提供了新的途径。     

基于匹配滤波的脆弱数字音频水印盲检测算法

根据原始水印构造匹配滤波器,并结合小波估计方法,提出脆弱音频水印的盲检测算法。在假定嵌入水印为噪声的情况下,利用小波不需要原始信号辅助信息即可估计该信号的特点,首先根据给定的估计门限估计了加入水印后的原始信号,从而实现了水印与音频信号分离。然后将水印与估计产生的噪声构成的混合信号送入构造的匹配滤波器作相关运算,根据滤波器的输出响应判断水印及载体是否受到攻击。实验结果表明,所提出方法对噪声、有损压缩、滤波、随机插入与删除等操作具有较高的敏感性。     

Clustering to improve matched filter detection of weak gas plumesin hyperspectral thermal imagery

The use of matched filters on hyperspectral data has made it possible to detect faint signatures. This study uses a modified k-means clustering to improve matched filter performance. Several simple bivariate cases are examined in detail, and the interaction of filtering and partitioning is discussed. The authors show that clustering can reduce within-class variance and group pixels with similar correlation structures. Both of these features improve filter performance. The traditional k-means algorithm is modified to work with a sample of the image at each iteration and is tested against two hyperspectral datasets. A new “extreme” centroid initialization technique is introduced and shown to speed convergence. Several matched filtering formulations (the simple matched filter, the clutter matched filter, and the saturated matched filter) are compared for a variety of number of classes and synthetic hyperspectral images. The performance of the various clutter matched filter formulations is similar, all are about an order of magnitude better than the simple matched filter. Clustering is found to improve the performance of all matched filter formulations by a factor of two to five. Clustering in conjunction with clutter matched filtering can improve fifty-fold over the simple case, enabling very weak signals to be detected in hyperspectral images     

FM—CW SAR系统及其发展概况

FM-CW SAR是一种新近被提出来的成像雷达体制，它结合连续波与合成孔径成像技术，具有体积小、重量轻、成本低、分辨率高等一系列优点。文章概述了FM-CW SAR系统及其信号处理特点，讨论了FM-CW SAR系统实现的难题所在；归纳了目前FM-CW SAR的几种应用背景及其主要参数；根据FM-CW SAR发展概况，讨论了FM-CW SAR进一步的发展趋势。     

基于仿生模式识别的多镜头人脸身份确认系统研究

提出了一种利用仿生模式识别原理以多镜头信息融合的人脸身份确认方法.讨论了以多镜头与多次采样建立仿生模式识别多权值神经元网络的基本理论.并介绍了以三个镜头五次采样作训练样本的实验系统,以及人脸预处理过程步骤.实验结果表明在确保无误认的前提下,正确确认率达96%,漏认率(即拒认率)为4%.实验中并对比显示了增加神经元网络复杂度提高识别效果的作用.     

声电荷转移器件（二）

着重介绍（Ｈ）ＡＣＴ器件的类型以及ＡＣＴ器件在系统中的应用。ＡＣＴ器件包括固定延迟线、抽头延迟线、固定（可编程）横向滤波器、模拟存储器等。它在雷达中的应用包括ＡＣＴ中频滤波、中频脉冲压缩滤波、中频杂波对消、脉冲多卜勒处理、自适应旁瓣对消等。     

基于逆滤波器的旋转不变匹配滤波相关识别

提出了用逆滤波器来进行旋转不变匹配滤波相关识别方法 ;采用级联变形滤波器可以实现透射匹配相关峰强度对透射输入能量的优化 ,大大改善相关峰的锐度 ,计算机模拟结果显示 ,对旋转图像 ,在平面内按 0°～ 32°旋转 ,每 4°取一灰度图像的旋转不变匹配滤波相关器 ,具有较好的相关不变识别性能 ,特别是目标图像在部分输入情况下也能较好地识别     

Neural-network-based adaptive matched filtering for QRS detection

We have developed an adaptive matched filtering algorithm based upon an artificial neural network (ANN) for QRS detection. We use an ANN adaptive whitening filter to model the lower frequencies of the ECG which are inherently nonlinear and nonstationary. The residual signal which contains mostly higher frequency QRS complex energy is then passed through a linear matched filter to detect the location of the QRS complex. We developed an algorithm to adaptively update the matched filter template from the detected QRS complex in the ECG signal itself so that the template can be customized to an individual subject. This ANN whitening filter is very effective at removing the time-varying, nonlinear noise characteristic of ECG signals. Using this novel approach, the detection rate for a very noisy patient record in the MIT/BIH arrhythmia database is 99.5%, which compares favorably to the 97.5% obtained using a linear adaptive whitening filter and the 96.5% achieved with a bandpass filtering method.