步进调频连续波信号应用于毫米波汽车防撞雷达

概述了工作在毫米波段的汽车防撞雷达的有关情况,针对虚警问题,提出了一种新的雷达发射信号体制,即变斜率步进调频三角形连续波信号,分析了该波形的特性,给出了其相应的信号处理,并提出了一种用于多目标环境中的目标检测算法．分析和仿真结果表明,新的信号体制具有良好的距离和相对速度分辨率,且易于产生和处理,同时其相应的多目标检测算法能够有效地去除虚警．     

步进调频连续波信号应用于毫米波汽车防撞雷达

概述了工作在毫米波段的汽车防撞雷达的有关情况,针对虚警问题,提出了一种新的雷达发射信号体制,即变斜率步进调频三角形连续波信号,分析了该波形的特性,给出了其相应的信号处理,并提出了一种用于多目标环境中的目标检测算法．分析和仿真结果表明,新的信号体制具有良好的距离和相对速度分辨率,且易于产生和处理,同时其相应的多目标检测算法能够有效地去除虚警．     

基才多相编码和收发阵列设计的机载MIMO雷达STAP方法

针对提高MIMO雷达多信号间正交性问题．提出了基于遗传算法优化提高多相编码信号自相关峰值、降低互相关峰值方法,提高多发射信号间正交性,降低盲速影响。针对天线阵列稀疏导致盲速、阵元密布导致天线孔径过小问题,从等效天线特征出发,给出了一种发疏收密阵列结构,与多相编码信号结合,进行动目标检测。仿真实验证明,基于多相编码正交信号和收发阵列设计。MIMO STAP可实现良好动目标检测性能。     

微弱光信号检测电路的设计和噪声分析

针对光信号检测电路对微弱光信号放大所带来的带宽和信噪比的问题,设计了一种微弱光信号检测电路。通过动态补偿的方法,在保证低噪声的同时使电路拥有良好的响应度。并通过电路的波特图形分析了电路的噪声,给出了减小电路噪声的方法。该电路主要用于检测快速变化的微弱光信号。     

基于FrFT的LFM信号检测与参数估计算法

针对线性调频(Linear Frequency Modem,LFM)信号的快速检测和高精度参数估计问题,在分析LFM信号特征和分数阶傅里叶变换(FrFT)原理的基础上,基于快速解线性调频技术,提出了一种LFM信号检测和参数估计算法,该算法将LFM信号检测由二维搜索转换为一维搜索,从而有效地减少了运算量。仿真结果表明,算法在低信噪比下具有良好的参数估计性能。     

802．16e中基于零虚警的初始测距检测算法研究

初始测距是802．16e系统中实现网络初始接入的重要过程。文章针对802．16e协议建立了初始测距信号模型,改进了原有频域检测算法。通过对接收频域信号进行功率检测并设置门限消除伪测距信号的影响,然后使用一种时频相结合的检测算法。结果表明该算法在检测概率和实用性上相对其它算法有着非常大的优势。     

莱斯信道下基于特征值的频谱感知技术

针对衰落环境下频谱利用率的提高,采用了一种基于接收信号自相关矩阵的特征值的检测方法。该方法基于随机矩阵理论,用最大最小特征值作为检验统计量来检测授权用户是否存在,从而改善频谱利用率。将随机产生的BPSK信号和捕获的DTV信号分别作为信号源在莱斯衰落信道下进行信号检测仿真。实验表明与传统能量检测方法的对比,该检测算法在莱斯衰落信道下具有良好的检测性能。     

脉搏信号相干检测方法的实验研究

脉搏信号是评估人体健康状况的一个重要因素。由于脉搏信号频率低、幅值小,常常被淹没在噪声内,为了提取脉搏信号,需要对信号进行去噪处理,因此采用相干检测实现去除噪声,通过对采集到的脉搏信号进行处理,得到了良好的输出波形。针对脉搏信号的特点,给出了实际可行的电路和测试方法。由实验结果可知,该系统具有良好的测量稳定性。     

复杂环境下高扩展性无人机信号检测识别方法

利用无人机与遥控器间的无线电信号进行无人机检测和识别是当前的研究热点。但在该领域，仍存在两个关键问题有待解决：一是如何在存在众多第三方信号的复杂电磁环境下有效检测识别无人机信号，二是如何保证检测识别系统针对新型无人机的快速扩展能力。针对这两个问题，提出了一种高扩展性的无人机信号检测识别架构。首先，利用YOLO神经网络模型应对复杂电磁环境下信号检测难题。该模型设计和训练面向通用电磁信号检测。完成信号检测后，利用“信号特征提取+支持向量机”结构设计无人机信号识别算法。该步骤计算复杂度低，模型参数少，因此对新型无人机具备良好的可扩展性。     

一种复杂环境中跳频信号检测和参数估计改进方法

信号检测与参数估计可为后续的信号解调分析提供依据,在电子对抗中起到重要的作用。针对复杂环境中跳频信号的盲处理问题,针对跳频信号模型进行分析,提出了一种基于滑动相关与小波变换结合的改进方法,更好地完成了检测与参数估计。该方法可较好地克服瑞利信道衰落和传播损耗的影响,检测性能良好,且跳频参数估计精度较高。最后,通过计算机仿真验证了改进方法结果的有效性,且正确率高,具有工程实用性,性能也优于过去的一些算法。     

An Asynchronous Design for Testability and Implementation in Thin-film Transistor Technology

This paper presents a scan chain design for dual-rail asynchronous circuits. This is a true asynchronous scan chain because no clock is needed even in scan mode. This is a full-scan design for testability (DfT) so only combinational automatic test pattern generation (ATPG) is needed and the fault coverage of generated test patterns is very high. This technique can be applied to various kinds of asynchronous circuits, including pipelines, state machines, and interconnects. Experiments on an 8051 datapath circuit show that the coverage is as high as 99.59%. This technique has been proven to work successfully in 8 μm Thin-film transistor (TFT) technology on the glass.     

A design for high noise rejection in a pseudodifferentialpreamplifier for hard disk drives

A study of supply and system noise rejection for a pseudodifferential amplifier is presented in this paper. This pseudodifferential amplifier is aimed at high data-rate disk drive signal sensing and preamplification applications. This high rejection was achieved by improving the rejection of the pseudodifferential amplifier and also by carefully designing the interconnect flex circuit where the preamplifier is mounted. The measured rejection to power supply, ground and system noise is above 50 dB over a 300 MHz bandwidth. This is significant for a pseudodifferential amplification system. The gain of the preamplifier is 47 dB and write mode to read mode switching time is 210 ns. This preamplifier currently supports disk drive data rates over 270 Mb/s     

Optimization of TFRC Loss History Initialization

This letter deals with the initialization of the loss history structure in the TFRC (TCP-friendly rate control) mechanism. This initialization occurs after the detection of the first loss event after every slowstart phase. The loss history is crucial for the algorithm since it returns the packet loss rate estimation. This estimation is used in the TFRC equation to compute the sending rate. In this letter, we propose a new method to compute the packet loss rate which is more computationally efficient and remains as accurate as the classical commonly used method. The motivation of this work is to reduce the computation time and formulate a unified computation scheme. This method is based on the Newton's algorithm issued from numerical analysis of the TCP throughput equation. This proposal is evaluated analytically and the results show a significant improvement in terms of the computation time     

The Balun ?Formalized?

The balun is in widespread commercial use and is an important systems component. This suggests that it may be of use to consider it as a unique element and formalize its qualities. This is attempted in this paper. The balun is shown to be one combination of a more basic element. This new element is termed "Ison" as an acronym for "isolation network." Various Ison combinations are shown and discussed.     

N版本编程技术的软件可靠性分析

针对解决高可靠计算机系统所需要的N版本编程技术，本文提出了对其可靠性进行分析和评估的基本方法。还特别针对使用了N版本编程技术而残存的共性故障进行了详细的分析，对一般的工程实践具有理论指导意义。     

基于AM79C874高速以太网控制器MAC层的设计与实现

阐述了以太网控制器AM79C874的应用———高速以太网控制器MAC(媒体访问控制)层的设计与实现。介绍了该芯片的主要性能,以及以太网帧结构、CRC(循环冗余校验)-32的实现和载波侦听协议。给出了系统设计硬件电路以及部分软件源代码。在FPGA内实现对AM79C874初始化与控制,并实现了简化的TCP/IP协议,使该嵌入式设备成功地与PC机互连。     

Reduction of boundary artifacts in image restoration

The abrupt boundary truncation of an image introduces artifacts in the restored image. The traditional solution is to smooth the image data using special window functions such as Hamming or trapezoidal windows. This is followed by zero-padding and linear convolution with the restoration filter. This method improves the results but still distorts the image, especially at the margins. Instead of the above method, we propose a different procedure. This procedure is simple and exploits the natural property of "circular" or periodic convolution of the discrete Fourier transform (DFT). Instead of padding the image by zeros, it is padded by a reflected version of it. This is followed by "circular" convolution with the restoration filter. This procedure is shown to lead to better restoration results than the windowing and linear convolution techniques. The computational effort is also improved since our method requires half the number of computations required by the conventional linear deconvolution method.     

冲击噪声环境中最小"几何功率"误差波束形成算法

本文提出一种适用于任意未知统计特性的代数拖尾冲击噪声(包含所有对称α稳定分布噪声)环境下的波束形成算法.算法利用输出信号和参考信号之间"几何功率"误差的最小化来求解最优权向量."几何功率"误差定义成误差信号的对数矩的形式.我们采用迭代复加权最小二乘估计来求解最小"几何功率"误差波束形成权向量.与基于最小分数低阶误差波束形成算法相比,最小"几何功率"误差波束形成算法计算更为简单;不需要噪声特征指数的先验信息或估计;适用于更广的冲击噪声环境;具有更小的估计误差.计算机仿真验证了算法的有效性.     

Fuzzy-associative-memory-based knowledge construction with anapplication to a human-machine interface

A fuzzy knowledge construction method is proposed for application to human-machine interfaces. This paper considers a human movement estimation system to be one of the interfaces. This estimation system transforms human physical movements into qualitative linguistic labels. For example, the degrees of magnitude and speed of the physical movement are represented by qualitative words. It is difficult to construct the transformation knowledge because the relation between the movements and the labels is fuzzy. This paper proposes a method of constructing the knowledge. This proposed method uses a fuzzy associative memory organizing units system and is applied to estimating human sports movements. Experimental results show that the proposed method is suitable for application to human-machine interfaces     

Electrostatic potential of impurities in quantum wells

The method of images is used to calculate the electrostatic potential of an electric charge inside a double barrier structure. This potential is important for finding impurity energy levels in the quantum structure and has never been used before in exact form. The media were modeled by assigning different dielectric constants to the barriers and to the well. The highly doped contacts were assumed to have infinite dielectric constants. This method is based on calculating the Fourier transform parallel to the interfaces of the potential. This function can be obtained in closed form. The potential is then obtained by inverse Fourier transform. This integral is computationally more efficient to evaluate than the direct sum of Coulomb image terms