基于量程自动转换技术的数据采集系统

针对传感器实验台输入信号范围宽的特点，研制了以89C51RD2单片机为核心数据采集系统。该系统采用了可编程放大器、AD574及其保护电路，结合软件控制量程自动转换电路，把输入任意范围的采集信号自动进行调整放大倍数，使数据采集系统始终具有较高分辨率，较强的自适应能力。此外，通过该系统与PC机进行通信，采集的数据可以在计算机上实时动态显示。     

基于JFET的高精度可程控放大电路设计

微弱信号常常伴随大量的噪声且驱动能力较弱,给精确测量带来很大难度。基于结型场效应管的程控放大器以压控放大电路为核心,通过单片机C8051F020控制12位D/A输出,改变工作在可变电阻区的结型场效应管的栅极电压以改变反馈电阻,从而实现放大倍数精确调节,使整个系统操作起来更加简单、方便。系统实现对信号1到1000倍放大并可程控,通过液晶显示输入、输出值和放大倍数。测试结果显示系统能够对最小1mv的输入信号进行预定放大且具有较高的精度;以JFET为核心的压控电阻工作速度快、可靠性好、控制灵敏度高,无机械触点使其噪声较低;系统12位A/D、D/A均集成在单片机内部,缩减了复杂的外围电路,可靠性高;系统还具有输入电阻大、共模抑制比高等特点。因此在数据采集系统、自动增益控制、动态范围扩展、远程仪表测试等微弱信号测量方面使用尤为适宜。     

自适应数据采集与重构算法仿真研究

针对固定采样周期和输入输出增益的动态信号数据采集观测失效问题,以二阶系统的阶跃响应过渡过程为研究对象,提出了一种采样周期和信号增益自适应数据采集与重构算法,能够根据实时系统的结构参数自动调整采样周期、数据采集输入调整倍率和数据重构输出匹配倍率,从而自动适应信号幅值和过渡过程调节时间的变化,实现有效观测.设计了自适应数据采集与重构MATLAB仿真程序,并借助一组具有代表性的检验试样运行验证了这种算法的正确性.     

量程自动转换电压表的设计与实现

在智能仪器中,自动量程转换通常采用继电器的切换来选择。优点是导通阻抗小,开路阻抗大,但其存在着体积大,驱动电流大,动作慢,容易老化等缺点。本系统采用运算放大技术来实现自动量程转换机制:先把输入电压通过同一个阻抗网络进行衰减;然后通过运算放大器将此信号进行放大,用CD4051模拟开关选择不同的放大倍数实现量程的转换。     

基于随机共振的驱动桥故障诊断方法研究

结合驱动桥运行时的实际情况,通过分析随机共振原理,给出了一种自适应随机共振算法.该算法能够根据输入信号自动调节系统参数,使其达到共振从而提取淹没在强背景噪声下的有用信号特征.通过仿真实验验证了该自适应算法能够从强背景噪声中提取一个和多个频率的信号.将该自适应算法应用于驱动桥故障检测中,结果表明该算法能够区分和识别驱动桥存在的不同故障类型.     

基于嵌入式系统的自适应滤波器研究

自适应滤波器具有在未知环境下良好的运作并跟踪输入统计量随时间变化的能力。其原理就是利用前一时刻已获得的滤波参数,自动调节现时刻的滤波参数,从而达到对当前信号进行最优化滤波的目标。本系统以STM32为核心,实现自适应滤波器的算法,以A/D、D/A模块为辅助,实现对模拟有用信号和干扰信号的采集,以及原始信号的恢复。     

单片机控制的自动选择八档数字增益的数据采集系统

介绍单片机数据采集系统的构成和工作原理，单片机控制的放大电路可根据输入信号的大小经过三次比较调整后用最佳增效放大信号，使输出落入设定的窗口范围之内，从而提高数据采集精度，实现自动量程变换，还介绍了自动机零和自动定标原理。     

一种高速数据采集系统前置通道的设计

讨论了高速数据采集系统前置通道的性能指标及设计原则，给出了作者设计且已实现的前置通道的系统构成及各个环节的结构，说明了其设计计算方法，特别详细详细了如信号幅度的调整，偏置量的调整与输入耦合及放大，触发等问题，文中讨论了ＡＤＣ的输入范围，输出显示垂直灵敏度，输入信号幅度值范围，衰减档的设置及放大倍数等之间的关系，给出具体设计参数，同时还说明了计算机自动设定衰减档的方法。在解决偏置电平的调整问题上，语     

单片机多路光强信号检测系统

介绍了单片机多路光通信号检测系统的研制。该系统采用８０３１单片机为微处理器，ＡＤＣ０８０４实现Ａ／Ｄ转换，４０６７作为模拟多路开关，根据需要可扩充输入通道数，能实现放大倍数的自动调节，并实现与ＰＣ机的通信，传输数据供其处理。     

带浮点放大数据采集器

<正> 一、概述带浮点放大数据采集器广泛应用于地震爆破、建筑施工等微信号的采集处理系统,也可用子高精度的自动控制系统。浮点放大器能根据输入信号的强弱自动选择放大倍数,使得微信号能得到一定程度的放     

小信号放大电路任意波形THD全自动测量系统研究

总谐波失真THD是衡量信道非线性程度的重要指标,应用于音频小信号放大电路的任意输出波形识别和总谐波失真的全自动测量系统成为检测信号放大性能的有效手段。为准确计算放大后的波形总谐波失真度,采用了快速傅里叶变换FFT技术。从提高系统效率角度,使用高频率采样并半数提取的技术方案。通过动态控制继电器、阻容元件及多级放大等手段,合理调整放大系统静态工作点的位置和输入波形大小,实现不同类型的失真波形输出。基于stm32f103c6单片机,联动开关一键式完成任意波形采集、识别、计算和显示,极大提升了小信号放大电路失真度测量的工作效率。Matlab运算仿真、Multisim电路仿真及实物测试表明,多级晶体管放大一致性调节电路和单片机FFT运算组成的小信号放大电路任意波形THD全自动测量系统,可准确、实时识别波形并计算出总谐波失真,一键式切换设计操作方便、节约成本,颇具实用价值。     

超声波传感器深度增益补偿电路设计

为了补偿超声探伤信号在动车组转向架中的传播损耗,利用超声波传感器,根据深度增益补偿的基本原理和微弱信号在不同深度处的衰减规律,设计了基于现场可编程门阵列(FPGA)的数字可控制式的增益放大补偿方法和电路。由XC6SLX16型FPGA的PLL模块产生精确的时钟控制信号,并输出数字量到DA芯片产生补偿电压曲线控制AD8330的放大增益倍数,再使深度补偿增益后的回波模拟信号进入LTC2249芯片内转换成数字信号,以便为下级数字信号再处理使用。实验结果表明:在超声波探伤仪系统的电路输入端加入频率为5 MHz、峰峰值为2 mV的正弦波激励后,通过改变步进值为5 dB的3种不同增益的大小,可以实现不同的放大增益,使衰减得到补偿。     

An adaptive data detection algorithm based on intermittent chaos with strong noise background

In order to realize the signal detection under the condition of lower SNR, this paper introduced the adaptive phase length based on the Duffing chaotic system and verified the measured signal at the optimal excitation frequency. The existence of the target signal was judged by observing whether there are two consecutive intermittent chaos in the time domain. Then the envelope of the intermittent chaos was obtained by Hilbert transform. Finally, the exact value of envelope spectrum was obtained by using the one-and-half-dimension spectrum, which can calculate the precise value of the frequency of the signal to be measured. The experimental results showed that the proposed algorithm can achieve a lower SNR than the conventional detection. Compared with the general chaotic detection, this algorithm can realize smart self-adaptation. It is unnecessary to specify different excitation frequencies and chaotic thresholds for different frequencies to be measured. In addition to the existence of the target signal judgment, the algorithm can also achieve accurate calculation of the frequency of the signal to be measured.

     

Fractional stochastic resonance multi-parameter adaptive optimization algorithm based on genetic algorithm

The output effect of fractional-order stochastic resonance (FOSR) system is affected by many factors such as input system parameters and noise intensity. In practice, many tests are needed to adjust parameters to achieve the optimal effect, and this way of “trial and error” greatly limits the application prospect of FOSR. Based on genetic algorithm, a suitable adaptive function was established to adjust the multiple parameters, including the fractional order, system parameters, and the input noise intensity of the fractional bistable system. Simulation results showed that the algorithm can achieve joint optimization of these parameters. It was proved that this algorithm is conducive to the real-time adaptive adjustment of the FOSR system in practical applications and conducive to the application and extension of FOSR in weak signal detection and other fields. The proposed algorithm has certain practical value.

     

基于动态扭矩传感器的荷重检测

动态扭矩传感器直接连接于旋转动力设备和荷重装置之间,可以输出与实际负载相关联的力矩信号.为了从动态扭矩传感器输出的力矩信号中得到实际负载,在荷重模型建立阶段,通过给荷重装置施加不同的负载,并对动态扭矩传感器输出力矩信号对应的AD转换值进行灰色关联校正,得到趋于稳定的AD转换校正值,在此基础上,利用移动最小二乘回归(MLSR)实现对荷重装置实际负载的非线性回归,得到实际负载与AD转换校正值间的非线性模型.在荷重检测阶段,进一步利用灰色关联校正并结合实际负载回归模型,得到荷重装置最终的实际负载.试验结果表明,结合灰色关联校正及移动最小二乘回归模型,荷重检测误差低于±0.3%.     

基于带通滤波器的幅频特性调节光电开关灵敏度

研究探讨了调制光频率与检测距离的相关性,旨在通过软件改变红外调制光频率,实现"一键式"智能调节检测距离.以连续周期矩形脉冲信号为例,选用二阶窄带带通放大电路对输入信号进行放大和滤波处理,使不同频率的脉冲信号经过窄带带通放大器自动调节其输出信号幅度,进而影响传感器的灵敏度.经理论推导、仿真设计、实验分析,结果表明:当设定脉冲幅值和占空比为常数时,改变脉冲信号频率可实现传感器灵敏度的调节,从而实现对检测距离的调节.即当ff0时,灵敏度随着f增大而减小.在红外光电开关传感器上应用该方法实现了利用软件调节频率来调节传感器的测量距离.     

Dynamics and stability of a delay-locked loop

We discuss the transient behavior of a delay-locked loop which is designed to generate a delay-error signal that is proportional to the difference in the autocorrelation function of the input signal at two points separated by a fixed time2tau_{1}. When the input signal is a sine wave, we present an exact solution which shows that the system is stable and achieves a delay lock with an ambiguity of an integral number of periods. The second input considered is that of a stationary, ergodic, and band-limited Gaussian signal. In this case we present an approximate analysis which predicts that for times long compared to the inverse bandwidth of the random signal that the delay error is log-normally distributed. For this case we develop the almost sure sample stability criterion [1]. When this criterion is met, the system sample solutions are stable with probability one independant of the system amplification. We also develop stability criteria which limit the system amplification for stability of the first and second moments of the time delay.     

用于星载SAR数字AGC增益控制的双门限步进法

首先对自动增益控制(AGC)电路的模拟和数字实现方法进行了比较,指出星载合成孔径雷达(SAR)系统采用数字AGC的必要性;然后针对数字AGC增益控制产生算法进行了讨论,提出了一种实用的数字AGC增益控制产生算法--双门限步进法。该算法配合数控衰减器非常适合数字AGC的工程实现,实验结果证明:采用该算法的AGC设计具有很好的收敛性,并且在后续处理中能够精确地恢复信号原来的幅度。     

A software architecture centric self-adaptation approach for Internetware

Being one of the basic features of Internetware, self-adaptation means that the software system can monitor its runtime state and behavior and adjust them when necessary according to pre-defined policies. Focusing on the three fundamental issues of self-adaptation, including the scope, operability and trustworthiness, a software architecture （SA） centric approach for Internetware＇s self-adaptation is presented in this paper. All of the self-adaptive actions, i.e. monitoring, analyzing, planning and executing, are performed based on SA. In detail, runtime state and behavior of Internetware are represented and changed in the form of runtime soft- ware architecture. The knowledge for self-adaptation is captured, organized and reasoned in the form of SA so that automatic analysis and decision-making are achieved.