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1.
本文介绍了一种采用离散傅里叶变换的高精度数字频谱分析方法,用它实现了双音多频(DTMF)信号的频率分离与识别,得到了有价值的结果。  相似文献   

2.
一种图象纹理特征提取与分割的新方法   总被引:2,自引:0,他引:2  
赵荣椿 《电子学报》1994,22(4):46-52
本文介绍了一种用于提取图象纹理特征的新的二维最佳数字滤波器(ODF),该滤波器是基于有限长球序列(FPSS)和离散付里叶变换(DFT)设计的,它具有能量损失最小的最佳频率响应特性。用若干具有不同中心频率和带宽的这种滤波器覆盖频率平面,可以抽取图象的纹理转征,进而利用一个非参数分类器,可对纹理图象实行有效的分类和分割。文中给出了一个人工纹理图象和一个自然纹理图象分割的实例。  相似文献   

3.
雷达动目标检测的实时信号处理原来一般用模拟器件和通用数字信号处理器(DSP)实现。本文设计了基于数字专用集成电路的雷达目标检测实时信号处理系统,本文对该信号处理系统的雷达背景视频产生,单元平均恒虚警率(CFAR)检测,杂波图形成,动目标提取,视频信号积累,雷达定时器和控制等用现场可编程门阵列(FPGA)进行了专用集成电路设计,该系统性能稳定,抗干扰能力强,体积小,便于调试,已投入实用。  相似文献   

4.
提出了利用相干X波段雷达检测小块流冰的新的检测方案。这种方法利用威格讷-维尔(WV)分布在相关时间-频率空间进行检测。介绍了两种独立的分类法。第一种方法从接收信号的模糊函数中提取分类特性,并根据这些特性用神经网络进行检测。第二种方法用主分量分析(PCA)法从时间-频率空间提取适用于分类的主要信息。利用实雷达数据介绍了结果,而且还把所提出的方法与一般的多卜勒恒虚警率(CFAR)处理机作了比较。  相似文献   

5.
图像矢量量化—频率敏感自组织特征映射算法   总被引:17,自引:0,他引:17  
用神经网络实现图像矢量量化是一种非常有效的方法,本文在分析自组织特征映射(SOFM)算法的基础上,提出了一种频率敏感自组织特征映射(FSOFM)算法,并对网络学习训练参数的优化进行了探讨。实验表明,FSOFM算法优于SOFM算法。  相似文献   

6.
对单散射点和多散射点转动目标产生的雷达回波进行建模,分析了转动散射点对雷达回波的调制,使用CLEAN算法思想分离多散射点的信号;使用不同的带有加速度和加加速度调制的信号对回波信号进行匹配傅里叶变换,通过搜索的方式提取出与目标信号匹配最好的加速度与加加速度值;使用最小二乘法估计目标的转动频率,进而提取出目标的其他转动参数,在存在多普勒混叠的情况下通过提取目标的加速度估计值实现了对多散射点的转动目标的参数估计。最后,通过仿真实验验证了方法的有效性。  相似文献   

7.
翟庆林  张军  付强 《电光与控制》2008,15(2):13-15,26
分析了波束内多目标鉴别技术的重要性,从应用的角度,提出了变尺度离散Chirp-Fourier变换的概念。通过和传统离散傅里叶变换的比较,显示出该变换的优越性。分析了多普勒雷达体制下目标回波信号的形式,并对变尺度离散Chirp-Fourier变换的速度分辨力和加速度分辨力进行了研究。针对波束内多目标的鉴别,提出了一种有效的基于变尺度离散Chirp-Fourier变换的多目标鉴别方法。该方法首先进行加速度鉴别,接着提取加速度,并进行加速度补偿,然后再进行速度鉴别。仿真结果验证了该方法的可行性和有效性。  相似文献   

8.
王兆华 《通信学报》1995,16(1):101-106
本文用离散Fourier变换(DFT)研究DPCM系统。预测误差是原信号和预测系数的循环卷积,耐解调由Fourier变换实现。在这种DPCM中,预测前还可以对图像作平滑等处理以减小预测误差。  相似文献   

9.
静像数据压缩及其标准JPEG(下)   总被引:3,自引:0,他引:3  
静像数据压缩及其标准JPEG(下)曾国良,丁宗豪七、离散余弦变换DCT图2中方框5的作用是将“二维”空间的图像数据用离散余弦变换DCT公式变换到二维频域成为二维频率系数。在叙述二维DCT公式以前,在此补充一些基本知识。我们知道离散傅氏变换DFT及其快...  相似文献   

10.
介绍多载波频率分集扩频多址系统(FD/SSMA)及其主要特点:FD/SSMA系统具有低功率谱密度、多址、抗干扰及抗多径能力,FD/SSMA系统的发送均可用离散傅立叶变换实现,FD/SSMA系统具有灵活性;FD/SSMA系统的同步不用考虑伪码的同步。  相似文献   

11.
This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.  相似文献   

12.
To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.  相似文献   

13.
We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4' -bis(2,2 -diphenyl vinyl)-1,1' - biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/NPBX (20 nm)/CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/NPBX (5 nm)/DPVBi (30 nm)/Alq(30 nm)/LiF(0.5 nm)/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N' -bis- (1-naphthyl)- N,N' -diphenyl -1, 1' -biphenyl-4,4' -diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (PPY)3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.  相似文献   

14.
本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。  相似文献   

15.
Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.  相似文献   

16.
It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV).  相似文献   

17.
正Happy New Year!As we step into a new year,we take a look back at the key feature topics covered in China Communications over the past 12 months and set out our expecta-  相似文献   

18.
Call for Papers     
正Introduction Jointly sponsored by the China Institute of Communications(CIC)and the IEEE Communications Society(IEEE ComSoc)since the year 2013,China Communications,currently,is aiming to gradually realise the transition from journal to magazine content and style.  相似文献   

19.
正For a long time,optical and wireless systems/net-works are developed in separate communities witha few attempts for in-depth convergence.In fact,it prom-ises many advantages to combine the optical and wire-less technologies in the levels of systems and networks.Recently,both academia and industry have made manyefforts to enter a new phase of development to take op-tical and wireless systems as fully integrated networks.To provide high bandwidth and reliable service for bothfixed and mobile users,a well-designed network must  相似文献   

20.
正Smart Grid Communications The electric power industry is undergoing profound changes as the industry aims to capture the promise of a smart grid for a sustainable energy future.Enabled by the advanced sensing devices such as Phasor Measurement Units(PMUs),increasingly powerful  相似文献   

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