According to negative temperature coefficient of vbe and positive temperature coefficient of vt , a framework of band - gap voltage reference is investigated . the reference offer a source of pir , distributed three voltage , one as upper - threshold voltage of dual - threshold comparator , the other as lower - threshold voltage of comparator , the other as direct current voltage for second band - pass filter amplifier 同时利用pnp晶体管发射结电压的负温度特性和发射结差值电压的正温度特性设计了一个带隙基准电压源。此带隙基准电压源本身作为热释电红外传感器的电源电压,同时分压提供双限电压比较器的上限电平和下限电平以及第二级带通滤波放大器的直流电平。
This paper starts the research of the liquid floated pendulous accelerometer testing system according to the engineering . at first , this paper gives the brief introduction of the history and present status of accelerometer and its testing technology , the working principium and math model of the liquid floated pendu - lous accelerometer , and then , decides the binary width pulse force retrim loop as the design proposal of testing system , researches the transfer function of every part in the system emphasizly , analyses the stability of the whole accelerometer testing system from the angle of control theoretics by the open loop transfer function of system , and designed the correcting net , analyses the basal problems such as resolution , sampling restraint , precision and so on , designs the hardware testing circuits such as preamplification , band - pass filter , alternating amplifier , phase sensitive demodulatorn , pulse - width modulation , frequency scale circuit , moment current generator . finally , using the graphics program language labv - iew which is designed for testing field especially by ni accomplishes the solfware design of testing system , realized the testing functions 首先对加速度计及其测试技术的发展历史和现状,液浮摆式加速度计的工作原理和数学模型等作了简要的介绍,然后确定了以二元调宽脉冲再平衡测试回路为设计方案,并从控制理论的角度进行了分析,着重研究了系统中各部分的传递函数,利用系统开环传递函数分析了系统的稳定性,同时设计了系统的校正网络;分析了二元调宽脉冲再平衡测试回路的分辨率、采样约束以及测试精度等基本问题,并按照系统分析的结果设计了包括前置放大、带通滤波、交流放大、相敏解调、脉宽调制、频标电路以及力矩电流发生器等测试系统各部分硬件电路,验证了电路的正确性,最后按照测试系统的要求,采用了美国ni公司专为测试领域所开发的虚拟仪器工具? ? labview作为测试软件开发工具,利用该图形化编程语言完成了测试系统软件部分的设计,实现了测试功能。
In vibration test , the signal is always along with noise . if the noise belongs to white noise , fourier transform is very suit to identify and process it , after then remove it . but when there exists low energy impact signal , traditional band pass filter remove noise and the precise position of impact signal is blured 对于白噪声，由于它是稳定信号，所以也可以使用fourier变换定位，以便在合适的频段进行提取。但是对于低能量突变瞬态信号，在信噪比比较低的情况下，由于带通滤波的平滑作用，瞬态信号的位置信息也变得很模糊了。
Firstly , frequencies of each mode shape are gained through frequency spectrum analysis of time domain signals of key points . secondly , time domain signals , which correspond to structural mode shapes , are gained through band - pass filter technology . lastly , the corresponding mode shapes of each natural frequency are constructed by using time domain signals , which are processed by band - pass filter technology 该方法的基本思想是先通过对关键点处时域信号进行谱分析得到结构各阶振型对应的固有频率，然后通过带通滤波技术得到结构关键点在每阶固有频率下对应的时域信号，最后用滤波后时域信号构建结构在每阶固有频率下对应的振型。
The paper introduces the fundamental theories and characters of wavelet transform , especially the multi - resolution analysis and band - pass filtering characters , puts forward the optical realization of wavelet transform of 1 - d and 2 - d signals , analyzes the optical filter systems with wavelet transform , improves the feasibility and advantages of wavelet transform used into optical information processing . as a practical and typical application of optical - wavelet - transform in the field of optical information processing , the paper makes a fairly detailed study on the special information extraction of an optical image with a wavelet - filtering system 本文详细介绍了小波变换的基本理论和性质，重点叙述了小波变换的多分辨率特性和带通滤波特性，分析了光的衍射现象与小波变换之间的内在的联系，提出了广义小波变换的概念，为光学小波分析奠定了理论基础，给出了一维和二维信号小波变换的光学实现方法，用小波变换分析了光学滤波系统，证实了小波变换用于光学信息处理的可行性和优越性。
In this paper they study a position - detecting system based on microprocessor and psd ( position sensitive detector ) . the method is as follows : when the ac - signal from psd which is illuminated by modulated light source passes through an active band - pass analog filter , it filters the ac signal which represents the object light source . then the dc - converter circuit transforms it into dc - signal which is used to calculate the position 这一系统采用的方法是通过对位置敏感探测器psd受到调制目标光源照射后输出的模拟交流信号进行有源带通滤波，提取出代表目标光源的调制频率成份，再将该信号转变为用来参与位置解算的直流信号，然后选用单片机组成硬件电路，对直流信号进行采集处理并与计算机建立通信，把数据送入计算机进行位置解算，分析判别目标光源和psd器件的相对位置。
