高精度幅相检测系统的设计

为了提高幅相检测精度、简化电路、扩展频率范围,设计了一种基于AD8302高精度幅度相位检测系统。通过分析AD8302的特点以及工作原理,提出了几种提高相位检测精度的方法,并设计采用AD8302、DDS和单片机组成高精度幅相检测系统,成功地解决了AD8302相位检测过程中存在的二值性、非线性、移相以及校准问题,实现两路模拟输入信号的相位差和幅度差的精确测量。测试结果表明基于AD8302的幅相检测系统具有精度高、抗干扰能力强等优点。     

宽频带幅度比和相位差测量系统的设计

AD8302是一款集测量幅度和相位于一体的单款集成电路,且测量精度高,测量频带范围宽。适用于移动通信及接收系统。介绍AD8302结构原理及工作模式,并结合C8051F单片机对AD8302测得的2路信号的幅度比和相位差值进行模数转换,构建一个基于C8051F单片机的片上数据采集系统,并利用VB语言编写单片机与PC机的串口通信,可将实时采集到的数据送到PC机中。     

基于最小相位法重建电磁脉冲时域波形

电磁脉冲测量中常需要通过电流探头、天线等传感器将待测脉冲先转换成易于测量的电压信号。由于传感器一般只给出了幅度的修正关系而缺少相位信息,给重建脉冲波形带来很大困难。为了解决这一问题,引入了最小相位法,将传感器视为一个满足最小相位条件的信号传输系统,通过传感器的修正系数计算其相频特性,得到系统的冲激响应,进而恢复出待测的电磁脉冲的波形。通过对电磁兼容试验中几种常见脉冲的测试,验证了波形重建的效果。这一方法解决了脉冲敏感度试验中门限电平不易确定的难题,也为电磁脉冲测量系统的校准提供了参考。     

Multi‐regional query scheduling in wireless sensor networks with minimum latency

Query scheduling as one of the most important technologies used in query processing has been widely studied recently. In this paper, we investigate the Minimum Latency Multi‐Regional Query Scheduling (ML‐MRQS) problem in wireless Sensor Networks (WSNs), which aims to generate a scheduling plan with minimum latency under a more practical query model called Multi‐Regional Query (MRQ). An MRQ targets at interested data from multiple regions of a WSN, where each region is a subarea. Because the ML‐MRQS problem is NP‐hard, we propose a heuristic scheduling algorithm Multi‐Regional Query Scheduling Algorithm (MRQSA) to solve this problem. Theoretical analysis shows that the latency of MRQSA is upper bounded by 23A + B + C for an MRQ with m query regions , where is the maximum latency for non‐overlapped regions, is the maximum latency for overlapped regions, and is the accumulated latency for data transmission from the accessing nodes to the sink. Simulation results show that MRQSA reduces latency by 42.7% to 51.63% with respect to different number of query regions, network density, region size, and interference/transmission range compared with C‐DCQS, while guaranteeing energy efficiency. Copyright © 2012 John Wiley & Sons, Ltd.     

Throughput maximization in wireless powered communication networks with minimum node throughput requirement

This paper considers wireless powered communication network consisting of one hybrid access point and a set of one‐hop nodes. Hybrid access point conducts wireless energy transfer (WET) in the downlink and nodes conduct wireless information transmissions (WITs) in the uplink based on the time division multiple access (TDMA) mode. Specifically, for the scenario where each node has its own minimum throughput requirement and different nodes' data have different levels of utility, we aim to achieve the minimum node throughput constrained weighted sum throughput maximization (MT‐WSTM) by jointly optimizing the time allocations of the WET and the WITs. First, we formulate the MT‐WSTM problem as a nonlinear optimization problem and further transform it into a more tractable form. Then, we prove the MT‐WSTM problem is convex and develop an efficient algorithm utilizing the dual decomposition technique to obtain the optimal solution of this problem. Compared with two schemes which use the optimal WET time and allocate the surplus WIT time evenly to all nodes and solely to the best node, respectively, the weighted sum throughput of the MT‐WSTM scheme is obviously larger in both homogeneous and heterogeneous scenarios.     

基于中心对称梯度幅值相位模式的单样本人脸识别

针对传统人脸识别算法在单训练样本情况下识别 效果不佳的问题,提出一种基于中心对称梯度幅值 相位模式(CSGMP)的单样本人脸识别算法。首先,提取人脸图像的梯度幅值和相位信息;然 后,用一种新 的中心对称局部方向模式(CSLDP)算子对梯度幅值进行编码,再将梯度相位量化到8个区间 进行编码,将 二者融合形成人脸图像的CSGMP特征;最后,分块统计直方图特征信息,将所有块的直方图 串联后作为 人脸图像的特征向量,利用最近邻分类器分类识别。在YALE和AR人脸库上进行测试的结果表 明,本文所提方 法简单有效,对光照变化、表情变化和部分遮挡等环境下单样本人脸识别具有较好的效果。     

DESIGN OF POLYPHASE WAVE DIGITAL FILTERS WITH APPROXIMATELY LINEAR PHASE

It is well known that IIR digital filters require quite fewer computations,comparedwith FIR filters,in order to meet stringent magnitude specifications when the phase distortioncan be tolerated.An approximately linear phase,however,can be also obtained with the IIRfilter by making use of a technique without increasing the complexity.Based on a certain numberof attenuation zeros in the pass band,a new approach is developed for the design of polyphasewave digital filters with exact magnitude responses and Chebyshev approximation of the desiredphase responses.The minimum number of attenuation zeros is estimated,and some examples areincluded.     

A new procedure for the design of high order minimum phase FIR digital or CCD filters

The approximation problem for high-order minimum phase FIR filter is solved without requiring any polynomial factorization. A modified Parks-McClellan program is used to compute the amplitude function; the minimum phase function is then derived by a method using the FFT algorithm. The procedure is illustrated by the design of various high order filters; short computation time with no numerical troubles is achieved.     

Design of optimal minimum phase FIR filters by direct factorization

An improved method of designing optimal minimum phase FIR filters by directly finding zeros is proposed. The zeros off the unit circle are found by an efficient special purpose root-finding algorithm without deflation. The proposed algorithm utilizes the passband minimum ripple frequencies to establish the initial points, and employs a modified Newton's iteration to find the accurate initial points for a standard Newton's iteration. We show, with examples, that the proposed algorithm can be used to design very long filters (L = 325) with very high stopband attenuations.     

可规划相位FIR滤波器的神经网络设计方法

本文针对可规划相频响应的实系数FIR滤波器的逼近问题,采用一个三层复激活函数前馈神经网络来实现。该网络隐层各神经元的激活函数为复指数函数,将滤波器系数作为隐层各神经元到输出层的连接权值,通过对误差函数的最小化来调整权值,并根据网络特性与所要设计的滤波器的特点,提出了一些实际设计中训练样本集选取与误差加权值设置的规则。依托所采用的神经网络,根据上述规则,进行了两例可规划相频特性的实系数FIR滤波器的设计,结果表明所设计滤波器的相频响应较好地满足了设计要求。     

一种数字中频接收机的设计与实现

介绍了一种数字中频接收机的设计,对接收机的各个组成部分进行了原理分析和推导,包括可变带宽滤波器、ADC、基于多相滤波器的数字正交变换、抽取滤波器设计、基带信号处理单元设计,得出样机的各样性能参数。     

基于新型优化窗的多维全相位数字滤波器设计

提出一种通用的多维全相位数字滤波器的设计方法.基于一维原型全相位数字滤波器(APDF),通过多维抽取变换,设计出具有任意平行六面体通带的多维APDF,并保持奈奎斯特约束特性和零相位特性.利用一种新型优化窗函数设计了性能优异的一维加窗APDF,将其作为一维原型滤波器,生成了不可分离的多维加窗APDF.实例表明,在滤波器长...     

Design of optimum criterion for opportunistic multi-hop routing in cognitive radio networks

The instability of operational channels on cognitive radio networks (CRNs), which is due to the stochastic behavior of primary users (PUs), has increased the complexity of the design of the optimal routing criterion (ORC) in CRNs. The exploitation of available opportunities in CRNs, such as the channel diversity, as well as alternative routes provided by the intermediate nodes belonging to routes (internal backup routes) in the route-cost (or weight) determination, complicate the ORC design. In this paper, to cover the channel diversity, the CRN is modeled as a multigraph in which the weight of each edge is determined according to the behavior of PU senders and the protection of PU receivers. Then, an ORC for CRNs, which is referred to as the stability probability of communication between the source node and the destination node (SPC_SD), is proposed. SPC_SD, which is based on the obtained model, internal backup routes, and probability theory, calculates the precise probability of communication stability between the source and destination. The performance evaluation is conducted using simulations, and the results show that the end-to-end performance improved significantly.     

Study of capacity region and minimum energy of delay‐tolerant unicast mobile ad hoc networks using cell‐partitioned model

Capacity region and minimum energy function for a variety of delay‐tolerant mobile unicast ad hoc networks are studied by using a cell‐partitioned model. First, theorems about analytical expressions of network capacity and upper bound of minimum energy function are proposed and proved. Algorithm aiming at maximizing capacity and minimizing energy cost is presented and analyzed by Lyapunov drift method. Second, these two theorems are applied to several types of ad hoc networks. Expressions of network capacity and minimum energy function are obtained. Third, capacity property of a type of hybrid ad hoc networks is analyzed in detail. Relationship among limitation of capacity, node density, and coverage of base stations are investigated. Numerical analysis and simulation are carried out. Copyright © 2015 John Wiley & Sons, Ltd.     

基于Matlab和FPGA的CIC滤波器的设计

基于多速率信号处理原理,设计了用于下变频的CIC抽取滤波器,由于CIC滤波器结构只用到加法器和延迟器,没有乘法器,很适合用FPGA来实现,所以本文分析了CIC滤波器的原理,性能及影响参数,借助MATLAB的FDATool工具箱设计符合系统要求CIC滤波器,并利用Simulink结合具体的结构建模仿真,验证CIC滤波器性能是否达到要求,最后在FPGA上实现这个结构的CIC滤波器设计,并进行了模拟仿真,综合验证。     

On the construction of maximum residual energy resource broadcast trees with minimum diameter in static ad hoc wireless networks

Each node in a wireless ad hoc network runs on a local energy source that has a limited energy life span. Thus, energy conservation is a critical issue in such networks. In addition, it is in general desirable to construct routes with low hop counts as a route with a high hop count is more likely to be unstable (because the probability that intermediate nodes will move away is higher). In this paper, we address these two issues concurrently with energy conservation as the primary objective and low hop count as the secondary objective. One way of addressing the energy conservation issue is to construct routes that maximize the minimum residual battery capacity available among all nodes in each route. A broadcast tree with all routes satisfying this condition is referred to as a maximum residual energy resource broadcast tree. A maximum residual energy resource broadcast tree with the least diameter is referred to as a minimum diameter maximum residual energy resource broadcast tree and the problem of constructing such a tree is referred to as the minimum diameter maximum residual energy resource broadcast routing problem (MDMRERBRP). We propose an algorithm for MDMRERBRP and prove that MDMRERBRP is optimally solvable in polynomial time using the proposed algorithm. Copyright © 2005 John Wiley & Sons, Ltd.     

TMS320F28335及其最小应用系统设计

介绍TMS320F28335的性能特点、仿真工具和开发环境,给出了由TMS320F28335组成的最小应用系统,并结合实际应用介绍其复位电路、时钟电路、JTAG仿真接口电路以及电源模块的设计方法。     

980nm和1480nm泵浦L波段EDFA的优化设计

文章研究了980nm和1480nm泵浦的L波段掺铒光纤放大器（EDFA）的设计与仿真，得出了同向泵浦和双向泵浦两种情况下的最佳泵浦波长配置。     

基于AD9959的高精度多通道雷达信号源设计

现代相控阵雷达为了保证空间功率合成精度需要高精度的雷达信号,设计实现了一种以AD9959为核心的高精度多通道雷达信号源。信号源利用多片AD9959产生32路正弦波、线性调频以及相位编码等多种信号形式,并设计采用AD8302对多路信号的幅度和相位进行检测与调整。该信号源已应用实际工程中,现场实验结果表明,该信号源系统产生的高频信号频率稳定度高、相位幅度一致性好,完全满足对信号源的性能指标的要求。     

联合最小路径和能量调配的路由算法的实现

基于最小耗能路径和路由能量信息的结合,提出了一个新型算法,在节点生命周期上做出改善,同时延长整个无线传感器网络的生存周期.对节点的能量信息划分了等级,相应的等级都匹配对应相应的信息传递概率,并且还对网络进行了分块分层划分.在节点生命周期上有了很大的改善,并且延长了整个无线传感器网络的生存周期,网络节点之间以及网关和节点间的依赖关系更加明显,最佳路径以及结合路径的能量调配得以实现,提高了整个网络效率.所以算法达到了提高网络性能的要求,并且很合理.