基于AVR的自适应等精度频率测量方法及实现

根据等精度频率测量原理,分析测量精度、频率测量闸门时间及预置门时间三者之间的关系,并在此基础上提出了一种自适应等精度测量频率的方法.该方法的思想核心是对粗测获得的输入信号频率值进行判断,选择合适的分频因子,动态控制闸门时间,使得精测时,能够满足较宽的频率测量范围,并能够实现高精度测量.     

一种基于自适应频率估计的跳频捕获新方法

针对水声跳频通信,给出了1种基于频率估计的跳频同步捕获的捕获原理和捕获过程,捕获中采用1种简化的变专长自适应格型IIR陷波器算法估测跳频信号频率。仿真结果说明该算法在低信噪比下具有估计精度高和实时性好的特点,满足水声跳频系统捕获的要求,验证了该跳频捕获方法的优越性。     

基于FPGA的卫星数字频率信号处理关键技术研究与实现

采用等精度测频法及相应的数字信号处理IP核,以ALTERA公司Cyclone II系列EP2C70F896C6N FPGA为核心实现了某型卫星陀螺组合X、Y、Z轴3个方向上的角速度信号、温度信号的测量处理系统的设计。实验结果表明基于FPGA的数字频率信号处理系统相对于以往数字频率信号处理电路具有高精度、高集成度、高速和高可靠性的特点,满足航天系统对信号处理电路设计高标准的要求。     

一种新的平滑频率扫描方式及其实现

工程中常用的匀速频率扫描方式在频率拐点处的瞬时频率变化率 较大,针对此缺点,提出了一种新的频率扫描方式——平滑频率扫描,并推导出平滑扫描的 数学表达式。利用MATLAB进行建模仿真表明,平滑频率扫描可以有效减少扫描在频率拐点处 的瞬 时频率变化率,提高接收端的捕获概率。实际工程应用证明,该平滑频率扫描方式有效可行 。     

频率测量单片集成电路的研究

介绍了等精度测频的基本原理,以此为基础,设计了一种用于测量射频信号频率的单片集成电路.着重阐述了频率测量单片集成电路的构成和高频信号转换电路的设计.该电路芯片在0.18μm CMOS标准工艺线上完成了制作,封装于CQFP48中.经测试,测频范围可达40～1500 MHz,测频误差小于0.8 MHz,功耗小于100 mW.     

一种新的基于LMP准则的自适应正弦波频率估计算法

自适应IIR陷波器在许多不同的信号处理场合,尤其在估计淹没在噪声中的正弦波频率方面得到广泛应用。本文在研究了多种自适应IIR陷波器算法的基础上,提出了一种基于LMP准则的修正LMP-MNG算法,仿真结果验证了算法的有效性。     

一种频率测量芯片的实现

白行设计的用于频率测量的ＡＳＩＣ采用白顶向下的设计方法，用ｖｅｒｉｌｏｇ语言建模，使用ｃａｄｅｎｃｅｖｅｒｉｌｏｇ仿真工具，保证了芯片具有可靠的性能和精度，同时设计周期也大为缩短。     

OFDM中频率同步的一种实现方案

频率同步是影响OFDM系统性能的一个很重要的问题。在分析现有的几种算法基础上,对频率跟踪、频率捕获和频域细同步进行了非常细致的研究,提出可行的频率同步方案。     

一种自适应增强谱线算法的优化设计与实现

自适应谱线增强(ALE)算法能够提高高动态、低信噪比信号的载波频率估计精度.针对实际应用中该算法消耗硬件资源多、结构复杂、使用效率低等问题,提出了结合可编程逻辑门阵列(FPGA)优化的ALE算法结构方法,简化了ALE硬件电路.设计结果表明,改进ALE方法后,可实现信噪比为0～20 dBHz、最大多普勒动态为800 Hz/s的测控信号载波频率准确估计.     

系统频率测量方法研究及基于DFT的测频算法仿真

频率是电力系统运行质量和安全情况的最主要标志之一,集成保护与控制系统需集成低频减栽等控制方式,测频是低频减载算法的核心,本文较全面地阐述了电力系统频率测量的重要意义和这些年来的研究成果.以测频主算法的数学原理为线索,对现有的各种测频算法进行了分类和评述,并提出了频率测量的发展方向.在考虑到现有条件的基础下,考虑算法的实时性以及精度问题,选用基于DFT算法,并对该算法进行了matlab仿真.     

一种超宽带频率综合器设计与实现

介绍频率综合器指标要求,在比较频率合成常用方法的基础上描述一种具有三通道输出的小步进超宽带频率综合器实现构架,推导和分析关键设计参数表达式,计算理论性能指标,给出各个通道的详细实现方案。基于国产器件完成样机设计和测试。测试结果表明该频率综合器具有超宽带频率输出、低相位噪声、低杂散、低谐波、细步进输出等特点,满足指标要求。     

基于高速视觉的振动频率测量方法研究

针对传统视觉无法提取高频率振动信号的问题, 提出了采用高速视觉的方法。首先, 对高速相机拍摄的原始图像进行去噪和二值化预处理;然后,通过采用选取较大周围圆半径 和减小候选点数目的方法快速提取特征点;最后,提取特征点的位移量并进行频谱分析即可 得到振动频率。以钢锯条悬臂梁为实验对象分析其振动频率,实验结果表明提出的方法在保 证实时性的前提下与理论计算结果基本一致,证明了基于高速视觉的振动频率测量方法是可 行的,具有一定的理论意义和实用价值。     

一种数字化中频接收机的研究与实现

概述了软件无线电的发展和应用,为满足雷达中频接收机的数字化要求,介绍了C频段微波统一测控系统中应用软件无线电思想设计数字化中频接收机的方案,对其基本原理和实现的关键技术做了分析,最后给出了应用FPGA和DSP等器件实现该接收机的具体方法。整个系统集成度高,可靠性好,使用灵活,已在多个某型C频段统一测控系统中得到了应用。     

High two-signal dynamic range and accurate frequency measurement for close frequency separation wideband digital receiver using adaptive gain control and adaptive thresholding

In electronic-warfare (EW) receiver applications, real-time measurement of the radar signals' carrier frequencies is mandatory and considered to be one of the most important radar parameters. Accurate frequency detection can be used to sort and deinterleave signals in a dense signal environment where multiple signals arrive simultaneously presenting severe problems unless they can be differentiated appropriately. Researchers and engineers are actively looking for new algorithms for high resolution wideband receivers with easier implementation. This paper presents an adaptive gain control and dynamic thresholding wideband digital receiver to accurately detect two simultaneous high dynamic range signals, even when their signal frequencies are very close. The proposed fast Fourier transform (FFT) based receiver examines incoming signal characteristics and provides real-time accomplishment of these tasks, by way of using an adaptive gain-control amplifier, a squarer, two analog-to-digital converters, and two FFT's. The wideband receiver offers high probability of intercept over wide instantaneous RF bandwidths, high dynamic ranges and sensitivity. Two simultaneous signal accommodations and their characteristics are provided to demonstrate the improvements over presently used receivers in this field.     

SDH主干网测量研究与实现

网络测量是网络性能分析和行为研究的基础.通过建立SDH(Synchronous Digital Hierarchy)主干网测量模型,分析研究其中的关键技术,提出了一种高性能的硬件实现方案,最后实验验证了该模型和方案的可行性.     

Design and implementation of an adaptive neural-network compensatorfor control systems

Recently, many studies have been made for intelligent controls using the neural-network (NN). These NN approaches for control strategies are based on the concept of replacing the conventional controller with a new NN controller. However, it is usually difficult and unreliable to replace the factory-installed controller with another controller in the workplace. In this case, it is desirable to install an additional outer control loop around the conventional control system to compensate for the control error of the preinstalled conventional control system. This paper presents an adaptive NN compensator for the outer loop to compensate for the control errors of conventional control systems. The proposed adaptive NN compensator generates a new command signal to the conventional control system using the control error that is the difference between the desired reference input and the actual system response. The proposed NN-compensated control system is adaptable to the environment changes and is more robust than the conventional control systems. Experimental results for a SCARA-type manipulator show that the proposed adaptive NN compensator enables the conventional control system to have precise control performance     

Design and implementation of an adaptive controller for current-fedinduction motor

A model reference adaptive speed controller for a current-fed induction motor drive is proposed. The controller uses a proportional-integral (PI) adaptation to satisfy the hyperstability condition for load and machine parameter changes of the drive. Only the available information on the states and output of the reference model as well as the plant output are required. No explicit parameter identification is needed. The controller can be designed simply by using a reduced reference model without particularly degrading the performance, so it is easy to implement practically. The hardware implementation is detailed, and some experimental results are given to demonstrate its effectiveness     

A fast lock frequency synthesizer using an improved adaptive frequency calibration

An improved adaptive frequency calibration (AFC) has been employed to implement a fast lock phase-locked loop based frequency synthesizer in a 0.18 μm CMOS process. The AFC can work in two modes: the frequency calibration mode and the store/load mode. In the frequency calibration mode, a novel frequency-detector is used to reduce the frequency calibration time to 16 μs typically. In the store/load mode, the AFC makes the voltage-controlled oscillator (VCO) return to the calibrated frequency in about 1 μs by loading the calibration result stored after the frequency calibration. The experimental results show that the VCO tuning frequency range is about 620-920 MHz and the in-band phase noise within the loop bandwidth of 10 kHz is -82 dBc/Hz. The lock time is about 20 μs in frequency calibration mode and about 5 μs in store/load mode. The synthesizer consumes 12 mA from a single 1.8 V supply voltage when steady.     

一种高效的移动互联网网站安全监测方法研究与实现

本文对一种高效的移动互联网网站安全监测方法进行了研究,提出了一种高效率的网站安全综合监测技术方案,并进行了实现,能够集中、统一对网站系统的实时安全状态进行监测,可为网站安全管理及监测工作提供汇总的统计数据,量化工作取得的成绩。可实现对移动互联网网站安全情况进行实时统一监测,准确、及时发现各网站存在的安全漏洞等隐患。