A fast echo canceller initialization method for the CCITT V.32modem

An investigation is conducted of the use of a fast-converging frequency-domain adjustment method for the echo canceller that conforms to the CCITT V.32 standard. The method requires no additional processor cycles (or cost increase) over that already required during steady-state operation of the V.32 modem, and reduces the training period to a maximum of 7.5 s, and nominally about 2.5 s. The presence of intermediate echoes can be detected naturally with the presented methods. Simple modifications of the new method are also introduced to accommodate special situations where intermediate echoes and/or frequency offset are present     

一种新的雷达重频模式识别方法

针对雷达重频模式识别中存在的问题,提出了一组新的二维特征向量,对重频固定、重频抖动、重频参差、重频分组和重频滑变5种典型的重频模式进行了识别。仿真结果表明,该方法正确识别率高,为工程应用提供了一种新的思路。     

一种新型实时快速滚转角测量系统

针对滚转角测量系统中的实时快速图像处理需求,提出一种基于泰伯-莫尔效应的计算量小、快速高效并且精度高的图像处理算法。首先,对干涉图像进行频域滤波和空域中值滤波,去除噪声并平滑保留图像边缘;然后采用自适应二值化进行阈值分割,再进行细化并去除毛刺,剪切图像去除效果差的边缘数据;最后采用一种霍夫变换和最小二乘法求解条纹间隔进而求得滚转角。实验结果表明,测量误差小于2.5 arcsec,在PC机上完成一次运算时间约为400 ms。所采用的算法提高了图像处理速度。全部算法采用ANSI C编程实现,可移植到不同的嵌入式图像处理系统中,提高了算法的通用性和实用性。     

A new method of channel identification

A method of channel identification is proposed that exploits the spectral correlation properties of pulse- and carrier-modulated signals to identify channels in the presence of arbitrary noise and nearly arbitrary interference. Although a pilot or training signal is required, no replica of the transmitted pilot/training signal is needed at the receiver. The price paid for this simplicity and the tolerance to extreme channel corruption from noise or interference is that the method is slow. That is, relatively long averaging times are needed for measurement of the spectral correlation of the received signal     

A new method for the reduction of crosstalk and echo in multiconductor interconnections

Crosstalk and echo can be reduced in multiconductor interconnections, using (truly) matched terminations and a different modal variable for each transmission channel. We first study a conventional technique for reducing reflections, using grounded linear two-terminal circuit elements. Using the concepts of modal voltages and modal currents, we define a new method for the reduction of crosstalk and echo, which involves specific terminations, specific transmitting circuits to send signals, and specific receiving circuits to receive signals. We establish the design equations and show that the new method is related to a particular choice of eigenvectors, called associated eigenvectors. Simulations of two examples of implementation of this method confirm that it provides reduced crosstalk and echo. We also discuss the implementation of the new method with an interconnection having identical propagation constants for all modes. Finally, we compare the new method with a different concept based on modal variables and unspecified terminations.     

微带BPF的一种快速设计方法

基于对现有几种半波长微带BPF设计方法的分析,提出了一种在减少实际调测工作量的同时更快更准确的设计方法,它是在充分利用现有实际电路制备一个模板库的基础上进行适当的变换来实现最终设计。最后提供了一个5阶发夹型滤波器设计实例,实验结果和理论吻合较好。由理论分析和实验结果来看,该方法较传统设计方法不仅更加快捷,而且提高了设计初始值的精确度。     

一种快速求解波导模式瞬态响应的新方法

应用有限积分技术,构造出一种快速求解波导特征模瞬态响应的时域有限差分格式。应用该方法计算的结果与通常三维的时域有限差分方法计算的结果十分吻合,但该方法具有很高的计算效率。在新的差分格式下,通过人工添加损耗项,构造出一种新的损耗传输线模型;该方法改善了截断边界条件对虚假反射回波的吸收性能,使虚假的反射回波低于-60dB。     

A new and fast nonlinear method for association analysis of biosignals

In this paper, we present some original theoretical aspects of a fast nonlinear association measure based on the work of Cramér. The features of this new measure--the V measure--when applied to biosignals are also shown using simulated time series. A comparative study with other well-known association measures available in the literature of biosignals is presented. V was found to be twice as fast and more robust to nonlinearities than the classical cross-correlation ratio (r2) and more than 100 times faster than the nonlinear regression coefficient (h2), presenting similar behavior in the presence of nonlinear simulated situations. This new measure is very fast and versatile. It is appropriate to deal with nonlinear relations presenting usually a sharp peak in the association function enabling a high degree of selectivity for maxima detection. It seems to constitute an improvement over linear methods of association which is faster and more robust to the existing nonlinearities. It can be used as an alternative to more complex nonlinear association measures when computational speed is an important feature.     

A new method for system reliability bounds

It has been established that symbolic reliability evaluation problem is an N.P. complete problem and as such is computationally infeasible for large networks. This has led to increased efforts in search for more fast exact techniques as well as better approximate methods.This paper proposes an algorithm for determining improved (tighter) upper and lower bounds on system reliability of general (i.e. non-series-parallel) systems. The proposed algorithm, like most existing methods, requires the knowledge of all simple paths and minimal cutsets of the system. The system success (failure) function is the union of all simple paths (minimal cutsets). The system success and failure functions are then modified to multinominal form and these expressions are interpreted as proper probability expressions using some approximations. The proposed algorithm gives better bounds as compared to the min-max method, the method of successive bounds, Esary-Proschan bounds and Shogan bounds and is illustrated by an example.     

A robust off-line output error method for system identification

The model reference technique and Huber's minimax principle have been successfully used to develop an offline output error method for robust identification of systems. This method is named the robust iterative output error method with modified residuals. A convergence analysis of the proposed method has been included as well as some simulation results. In the presence of a small number of large errors (called outliers) in the input-output data, the presented method has demonstrated its distinctive advantages over not only the nonrobust methods but also previously developed robust methods. The main advantages are a fast convergence speed and satisfactory robustness. It is concluded that the method developed here is much superior to the other methods and therefore can be widely used in many real-time applications     

基于MPF的惯性导航系统快速对准技术

针对目前应用于惯性导航系统初始对准中的扩展卡尔曼滤波存在对准精度低、时间长的缺点,提出一种基于模型预测滤波的快速对准技术。该方法将惯性器件测量误差视为模型误差使用MPF进行实时预测,并以此来修正惯性导航系统的平台误差角。这样,MPF不仅有效提高了平台误差角的估计精度,而且降低了系统状态变量的维数,大大缩短了初始对准时间。仿真结果表明,MPF在平台对准精度和快速性方面均明显优于EKF,初时对准时间仅是EKF的10%,而对准精度却高于EKF。     

一种三维调制信号快速解调新方法

根据三维调制信号的特性,提出了一种新的三维调制信号的快速解调方法。该方法基于MUSIC算法,首先利用单次快拍来建立阵列数据的协方差矩阵,然后根据调制信号的先验信息对所得信号空间谱进行判决,来估计其极化辅角与极化相位角等信息,从而恢复出基带信号。分析与仿真结果表明,所提方法不仅可以避免谱搜索,大大降低MUSIC方法的运算量,而且适用于瞬时信号和快速运动信号的解调。     

一种可快速编码的QC-LDPC码构造新方法

为解决LDPC码的编码复杂度问题,使其更易于硬件实现,提出了一种可快速编码的准循环LDPC码构造方法。该方法以基于循环置换矩阵的准循环LDPC码为基础,通过适当的打孔和行置换操作,使构造码的校验矩阵具有准双对角线结构,可利用校验矩阵直接进行快速编码,有效降低了LDPC码的编码复杂度。仿真结果表明,与IEEE 802.16e中的LDPC码相比,新方法构造的LDPC码在低编码复杂度的基础上获得了更好的纠错性能。     

快衰落信道下OFDM系统的信道估计简化算法

在快衰落时变信道中，正交频分复用（OFDM：Orthogonal Frequency Division Multiplexing）系统子载波间的正交性会遭到破坏，由此引起的载波间干扰（ici：Inter-Carrier Interferellce）会对系统性能带来很大的影响。本文提出了一种利用时域线性模型的信道估计算法，利用随时间线性变化的模型描述信道。仿真结果表明，本算法能够有效地消除载波间干扰，降低系统的BER。与类似算法相比，当系统的BER性能相同时，算法复杂度大大的降低。     

基于马尔科夫识别的敌我目标识别新方法

针对敌我识别系统在现代战争中的保密要求,提出一种将马尔科夫系统识别技术应用于敌我识别的新方法,每个发射机按照系统分配的转移矩阵发射随机码,接收机利用已知的不同我方作战单元的转移矩阵,判断码序列所属,实现我方目标的识别。与传统方法相比,发射机每次按照一定的转移概率发射服从马尔科夫分布的随机编码,大大提高了敌方截获和破译的难度,提升了系统的抗欺骗干扰性能。仿真结果表明,该方法在发射序列比较长的情况下,可以获得准确的识别结果。     

一种军事假目标识别的新方法

通常的侦察手段对于军事假目标的识别能力有限,文中提出了一种新的军事假目标识别方法。在介绍偏振成像机理的基础上,分析了偏振信息检测和强度信息检测在物理含义中的区别。提出了获得偏振度图像的方法,通过理论分析,能够很好地分辨真假目标,证明了文中方法的科学性和可行性,对军事假目标的检测有重要意义。     

高层建筑的快速识别方法研究

利用卫星图像对高层建筑进行分类和定位,相比市售数据具有成本更节省、更新更及时的优势,在无线网络规划的环境调查工作中具有重要的意义。本文通过不同方法在高层建筑识别上进行对比测试,发现在高层建筑的识别上,使用VGG16网络具有最好的召回率。在算法和预训练网络的挑选上,需要根据数据集的特点进行仔细甄别。Faster R-CNN配以VGG16骨干网络是效果相对较好的一种方法。不同算法架构和预训练网络在不同的数据集上表现相差较大。     

一种新的可快速切入的H.264/AVC视频编码方法

提出一种新的可快速切入H.264/AVC视频的编码方法,该方法利用H.264/AVC标准所提供的多参考帧和内存管理控制操作等机制实现,可以在保持压缩效率不变的情况下,将新观众切入视频的速度提高5倍以上。