光电跟踪伺服系统的频率特性测试与模型辨识

基于光电跟踪伺服系统全数字化的特点,提出了一种新型频率特性测试方法。对该方法所使用的激励信号、数据采集方式、幅值和相位提取算法、模型递阶辨识算法进行了研究。首先利用数字运动控制器产生离散的正弦扫频信号,同时采集响应信号并存储在磁盘上;测试完毕,将文件传给PC机,利用Matlab进行数据处理,采用谱分析或者相关分析的方法计算输入输出信号的幅度比和相位差,最后利用递阶辨识算法将测量得到的数据转化为高精度的传递函数。应用结果表明：该方法简单快捷,成本低,测试精度高,具有重要的工程应用价值。     

数字中频幅相检测仪设计

介绍了基于T1公司高性能16位定点数宇信号处理器TMS320VC5416的幅相检测系统设计。对系统组成模块进行了详细的描述。该仪器同时测量两路信号的幅度和相位。与传统测量方法相比,具有较强的抗干扰能力和较高的精度。应用前景广阔。     

基于电压调幅的超声波流量计研究

针对非稳态流场中流体测量时存在的问题,在超声波流量计过零点检测判定渡越时间的基础上,采用电压调幅的方法产生超声波换能器激励信号,然后通过检测接收信号的幅值变化特征点定位波形。针对流场中流速不稳定可能导致的波形不稳定情况,采用中值滤波的方法减小误差。为避免ADC芯片位数和AD转换速率限制导致渡越时间测量误差问题,在数字波形特征点判定基础上,采用过零点检测从模拟波形上获得渡越数据。实验结果表明,该方法具有一定的可行性,可以达到对超声波脉冲序列准确处理、定位的目的,测量误差可以控制在在1.5%以内,可以达到二级精度仪表的要求水平。     

基于VHDL语言的数字波形发生器的设计

阐述了数字波形发生器系统的设计方案,给出了系统的原理框图,并对设计功能进行了描述;详细介绍了系统主要功能模块的作用和工作原理,并对部分模块在MAX＋PLUSIIIO．2中进行了仿真;仿真结果表明,系统能够产生正弦波、方波、三角波和锯齿波,产生的4种波的频率、幅值可以调节,还可以通过4位数码管显示输出波形的频率。     

A 32-Channel High-Speed Simultaneously Sampling Data Acquisition System

The system is intended for recording data in the multichannel diagnostic sections of experimental plasma facilities. It contains eight four-channel modules that record the shapes of single pulse signals, a controller module of the system bus of the crate, a fiber-optic communication line, and an interface card for connection to the ISA bus of a personal computer. The recording modules are based on 12-bit analog-to-digital converters (ADCs) with a sampling frequency of up to 50 MHz, ensuring a conversion accuracy equal to the least significant bit in a band of the input signal of up to 20 MHz. The ADC samples are fixed in 32-Kword/channel buffer storage units with a page organization. The current values of the amplitude of the input signals in all of the recording channels are measured simultaneously with a time jitter of no more than 0.2 ns. The software selects an amplitude conversion scale and a zero offset voltage value for each recording channel, as well as the current value of the sampling frequency for all the channels.     

Correlation based novel technique for real time oscilloscope triggering for complex waveforms

Frequency modulated signals being dynamic in nature changes their frequency with time. These signals are commonly used in sonar and radar applications, but also have other applications such as stimulus response analysis, vibration sweep testing and spread spectrum communications. Data acquisition and presentation of these periodic signals offer the challenge of live waveform presentation on oscilloscope. This paper presents an efficient technique for advanced oscilloscope triggering for periodic waveforms based on the concept of normalized correlation. The proposed technique is demonstrated using LabVIEW based intensive simulations on several test waveforms. Hardware implementation of the proposed technique is successfully demonstrated with the help of data acquisition (DAQ) card. This intelligence can be embodied into the digital storage oscilloscope (DSO), making it an intelligent measurement system, catering to wide variety of the waveform types. The proposed technique, simulation results, robustness study, comparison with other similar methods and implementation results are presented in this paper.     

一种信号合成电路的设计与实现

主要设计一种能够合成指定波形的信号波形发生电路,电路基于傅里叶合成,通过产生不同频率的正弦信号,将这些信号处理后送入加法电路可合成所需信号。主要由方波产生模块产生方波,分频与滤波模块对所得方波分频并滤成正弦波,放大模块对所得正弦波幅值进行调节,移相模块调整各频率正弦波相位,最终通过信号合成模块合成所需波形。     

全波形激光测距幅相误差改正方法

针对全波形激光测距中存在的幅相误差问题,提出一种基于神经网络的幅相误差改正方法。利用非合作目标探测信息,通过提取回波波形的形状信息、能量信息、梯度信息、对称性信息及距离信息特征参数,根据皮尔逊相关系数对特征参数进行分级,建立多回波特征信息与幅相误差改正的神经网络模型以校正全波形激光测量中各通道幅相误差的影响。实验使用5%、20%、60%、80%标准反射板及激光采集模块在室内对7种距离进行数据分组采集和处理,并与传统测量方法进行对比。结果表明,该方法可以有效减小全波形激光测量中幅相误差的影响,测量精度提高了51.2%以上。     

基于DDS技术的可调方波干扰的多功能信号发生器研究

利用单片机控制灵活的特点,采用软件方式实现信号生成和添加干扰.为方便添加方波干扰,系统采用模拟直接数字频率合成(DDS)基本工作原理方法,使用片外存储器替代DDS芯片的ROM波形查询表实现相幅转换.系统采用AT89C51单片机实现数据处理,DAC0832实现D/A转换,采用4×4键盘完成参数设定,液晶12864显示波形参数和操作提示,实现了正弦波、方波、三角波信号生成、幅值和频率调节,方波干扰添加以及各种波形信号的参数控制.     

波形曲率延拓在局域均值分解中的应用

局域均值分解（LMD）是一种能够将复杂的调幅调频信号自适应地分解为一系列单分量的调幅调频信号的处理方法,其分解过程存在端点效应,分解结果有一定程度的失真。针对此问题,提出根据波形曲率特征对信号端点进行极值延拓,通过特征波的曲率波动来筛选与边界波形最为相似的数据段,在此基础上将波形匹配曲率估计应用于LMD分解过程中, 并与镜像延拓及自适应波形匹配延拓方法相比较,验证了所提方法的优点。使用仿真信号与实际的齿轮故障数据进行试验与检测,结果表明,所提方法可以有效改善LMD分解过程的端点效应,提高分解精度。     

波形采集、存储与回放系统的设计

该系统以单片机和FPGA为核心控制器件,实现了波形采集、存储与回放功能。整个系统由信号调理、比较电路、采集存储、数据处理、人机交互等模块组成。信号调理模块采用高速低躁声运放AD8038实现高阻输入、幅度控制;比较电路采用LM311实现被采集信号周期的测量;数据采集模块采用AD5540芯片,在FPGA时序控制下采样;C8051F020单片机作为总控制器,与FP-GA内部的双口RAM和读写信号相结合,实现数据的存储,以及回放前数据的读取;信号输出部分采用DA芯片THS5651和高速运放AD8039相结合,实现了低输出阻抗和信号幅度的控制。经测试,系统功能齐全,波形完整,回放频率非常准确。     

针对 3×3 耦合器幅相非对称的光纤水听器解调方法

基于3×3耦合器法的光纤水听器解调容易受耦合器分光比非理想对称特性影响,导致水听器解调结果及测量信号不准确。为解决实际中3×3耦合器普遍存在的幅度、相位非对称引入的解调偏差问题,提出基于微分交叉相乘的干涉信号幅度和相位修正解调方法。通过对三路非对称干涉信号进行两两最小二乘椭圆拟合,得到干涉信号的实际幅度和相位参数,经去直流、归一化消除幅度不对称,并将所得包含非对称相位信息的信号两两微分交叉相乘,经三角函数变换解算信号相位及其修正系数,从而实现对光纤水听器输出信号的准确解调。仿真对比了本文方法和仅考虑幅度非对称情况的解调结果,并分析比较了两种处理方法随声信号频率、幅值变化的解调误差,前者得到接近理想信号波形的解调结果和更小的解调误差。依托消声水池开展了光纤水听器解调实验,在5～30 kHz频率范围对解调方法进行了对比验证,证明了本文解调方法的有效性和稳定性。     

Online feature-based multisensor object detection system for bucket-wheel excavators

This paper proposes the development of a monitoring system to be applied for a production system (bucket-wheel excavator). The system is based on a multisensor-based object detection system. The main objective of the detection system is to obtain—in real time—reliable decisions on the presence of large stones in the transported overburden. The highest possible detection rate and the lowest possible false alarm rate should be achieved to avoid disturbances or failures of the production process. Due to the complexity of the considered production system, different physical effects are taken into account. The detection system consists of two detection modules (acceleration and laser scanner module), a plausibility module (weightometer module), and a fusion module. The acceleration module consists of five acceleration sensors. The acceleration signals are individually undergone preprocessing, feature extraction, and classification processes. The preliminary decisions of different sensor channels are fused to obtain statements about the presence of large stones. In the laser scanner module, the signal is prefiltered, filtered, validated, and classified in order to detect excavated stones. The weightometer module is based on two load cells signals. It is developed to approve the plausibility of the positive statements of the acceleration module. The fusion module is developed in order to synchronize and combine the output statements of different modules to obtain the production system state with respect to the presence of an object. The detection system is developed based on the acquired knowledge from the analysis of the production process and the analysis of the acquired data during the production process. The designed system has been implemented using standard industrial hardware. The testing results to be reported show that the system requirements can be fulfilled.     

On the Evaluation of Chemical Relaxation Measurements with Sampling Technique and On-Line Processing

A relatively simple digitizing interface for use in chemical relaxation experiments is described. It is possible to sample by repeating the experiments and adding the data in a small on-line computer. This technique has considerably improved the accuracy obtainable in relaxation experiments as well as the speed of data acquisition. The relaxation data, which are corrected by the computer program for superimposed exponential decay processes of small amplitude, are available immediately after the experiment. By integrating the analog signal before digitization, nearly optimal electronic filtering is achieved. The technique has been extensively used in the pressure-jump technique but is applicable also to related methods. An example for the application to signals which do not change exponentially with time illustrates further possibilities of the proposed technique.     

Data taking from multiwire chambers and hodoscopes at IHEP physical setups

The LE-73 and LE-78 modules of MISS system designed for readout and recording of signals from multiwire chambers and hodoscopes are described. The use of an Altera FPGA provides a means for producing different modifications of the modules and adapting their operation to specific requirements of experimental setups. Owing to the availability of a high-speed internal memory, it is possible to design time-to-digital converters with a “common stop” and a 5-ns step and to store data in an internal FIFO memory.     

基于ODYSSEY的桥梁动态测试系统

为了满足大型桥梁动态测试中对测试仪器的要求,建立了一套基于Odyssey的用于桥梁动试验的动态测试系统。该系统可实现多通道信号同时采集,并对所测信号实时示波,整个系统由微机化仪器Odyssey实现其主要功能,结构紧凑,使用方便。Odyssey大的存储量,可对低频信号长时间连续记录用于测试信号的标定,满足了桥梁动载测试的诸多要求。最后,给出了某大跨径斜拉桥的振动实测数据及部分处理结果,得到了满意的应用。     

基于FPGA的数字存储示波器的研究

基于FPGA的数字存储示波器,以可编程逻辑器件ACEX1K30TC144-3和89c51单片机为核心,由通道输入调整、数据采集、数据处理、波形显示和操作面板等功能模块组成。系统中的数据采集及数据处理模块。采用了FPGA内制的RAMIP核,使系统的工作频率基本不受外围器件影响,经maxplusll延时分析,其内核频率可以达到40MHz以上。这对于数据处理速度和实时性要求比较高的应用领域具有重要的意义。     

滚动轴承振动信号的微机采集和分析系统

本文以286微机为主体建立了振动信号采集和分析系统.系统由信号测量,数据采集,预处理和信号分析几部分组成,能实现幅值域,时域和频域分析.系统的软件有良好的人机界面,使用十分方便.该系统成功地应用于滚动轴承振动信号的采集和统计特性分析,还可以推广应用于其它机械振动信号的采集和分析.     

一种实用任意波形信号发生器的设计

采用iSPLSI器件和单片机相结合的方法设计了一种任意波形信号发生器.信号的波形可通过编程任意产生,其它主要参数如幅度、频率等可程控.主要技术指标先进、达到实用要求.     

基于CPLD的光电编码器测量系统

为了提高光电编码器的反馈精度和消除正交波形中的抖动,提出了一种基于复杂可编程逻辑器件且具有倍频鉴相和滤波功能的光电编码器测量系统。介绍了光电编码器测量原理,将系统划分为滤波鉴相、倍频、计数3个模块,并对这3个模块进行了电路设计和仿真。仿真结果表明,该设计方法能够满足高精度伺服电机正交编码的信号处理要求。