The file is about lock-in amplifier and how it can apply to the use of our daily life
标签： amplifier lock-in about apply
上传时间： 2013-12-10
上传用户：koulian
Use Dspic30F4011 for design a lock-in Amplifier-Vietnamese
标签： Amplifier-Vietnamese lock-in design Dspic
上传时间： 2014-01-02
上传用户：问题问题
微弱信号检测装置 四川理工学院 刘鹏飞、梁天德、曾学明 摘要： 本设计以TI的Launch Pad为核心板，采用锁相放大技术设计并制作了一套微弱信号检测装置，用以检测在强噪声背景下已知频率微弱正弦波信号的幅度值，并在液晶屏上数字显示出所测信号相应的幅度值。实验结果显示其抗干扰能力强，测量精度高。 关键词：强噪声；微弱信号；锁相放大；Launch Pad Abstract: This design is based on the Launch Pad of TI core board, using a lock-in amplifier technique designed and produced a weak signal detection device, to measure the known frequency sine wave signal amplitude values of the weak in the high noise background, and shows the measured signal amplitude of the corresponding value in the liquid crystal screen. Test results showed that it has high accuracy and strong anti-jamming capability. Keywords: weak signal detection; lock-in-amplifier; Launch Pad 1、引言 随着现代科学技术的发展，在科研与生产过程中人们越来越需要从复杂高强度的噪声中检测出有用的微弱信号，因此对微弱信号的检测成为当前科研的热点。微弱信号并不意味着信号幅度小，而是指被噪声淹没的信号，“微弱”也仅是相对于噪声而言的。只有在有效抑制噪声的条件下有选择的放大微弱信号的幅度，才能提取出有用信号。微弱信号检测技术的应用相当广泛，在生物医学、光学、电学、材料科学等相关领域显得愈发重要。 2、方案论证 针对微弱信号的检测的方法有很多，比如滤波法、取样积分器、锁相放大器等。下面就针对这几种方法做一简要说明。 方案一：滤波法。 在大部分的检测仪器中都要用到滤波方法对模拟信号进行一定的处理，例如隔离直流分量，改善信号波形，防止离散化时的波形混叠，克服噪声的不利影响，提高信噪比等。常用的噪声滤波器有：带通、带阻、高通、低通等。但是滤波方法检测信号不能用于信号频谱与噪声频谱重叠的情况，有其局限性。虽然可以对滤波器的通频带进行调节，但其噪声抑制能力有限，同时其准确性与稳定性将大打折扣。
上传时间： 2013-11-04
上传用户：lty6899826
锁定放大是微弱信号检测的重要手段。基于相关检测理论，利用开关电容的开关实现锁定放大器中乘法器的功能，提出开关电容和积分器相结合以实现相关检测的方法，并设计出一种锁定放大器。该锁定放大器将微弱信号转化为与之相关的方波，通过后续电路得到正比于被测信号的直流电平，为后续采集处理提供方便。测量数据表明锁定放大器前级可将10-6 A的电流转换为10-1 V的电压，后级通过带通滤波器级联可将信号放大1×105倍。该方法在降低噪声的同时，可对微弱信号进行放大，线性度较高、稳定性较好。 Abstract: lock-in Amplifying（LIA）is one of important means for weak signal detection. Based on cross-correlation detection theory， switch in the swithched capacitor was used as multiplier of LIA， and a new method of correlation detection was proposed combining swithched capacitor with integrator. A kind of LIA was designed which can convert the weak signal to square-wave， then DC proportional to measured signal was obtained through follow-up conditioning circuit， providing convenience for signal acquisition and processing. The measured data shows that the electric current（10-6 A） can be changed into voltage（10-1 V） by LIA， and the signal is magnified 1×105 times by cascade band-pass filter. The noise is suppressed and the weak signal is amplified. It has the advantages of good linearity and stability.
上传时间： 2013-11-28
上传用户：黑漆漆
Open Source for the Enterprise Open source software is changing the world of Information Technology. But making it work for your company is far more complicated than simply installing a copy of Linux. If you are serious about using open source to cut costs, accelerate development, and reduce vendor lock-in, you must institutionalize skills and create new ways of working. You must understand how open source is different from commercial software and what responsibilities and risks it brings. Open Source for the Enterprise is a sober guide to putting open source to work in the modern IT department.
标签： Open Information Enterprise the
上传时间： 2013-12-26
上传用户：R50974
Features • Compatible with MCS-51® Products • 8K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 1000 Write/Erase Cycles • 4.0V to 5.5V Operating Range • Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 256 x 8-bit Internal RAM • 32 Programmable I/O Lines • Three 16-bit Timer/Counters • Eight Interrupt Sources • Full Duplex UART Serial Channel • Low-power Idle and Power-down Modes • Interrupt Recovery from Power-down Mode • Watchdog Timer • Dual Data Pointer • Power-off Flag
标签： 8226 Programmable Compatible In-System
上传时间： 2015-06-27
上传用户：dianxin61
About: hamsterdb is a database engine written in ANSI C. It supports a B+Tree index structure, uses memory mapped I/O (if available), supports cursors, and can create in-memory databases. Release focus: Major feature enhancements Changes: This release comes with many changes and new features. It can manage multiple databases in one file. A new flag (HAM_LOCK_EXCLUSIVE) places an exclusive lock on the file. hamsterdb was ported to Windows CE, and the Solution file for Visual Studio 2005 now supports builds for x64. Several minor bugs were fixed, performance was improved, and small API changes occurred. Pre-built libraries for Windows (32-bit and 64-bit) are available for download. Author: cruppstahl
标签： C. hamsterdb structure database
上传时间： 2013-12-10
上传用户：LouieWu
If you have programming experience and a familiarity with C--the dominant language in embedded systems--Programming Embedded Systems, Second Edition is exactly what you need to get started with embedded software. This software is ubiquitous, hidden away inside our watches, DVD players, mobile phones, anti-lock brakes, and even a few toasters. The military uses embedded software to guide missiles, detect enemy aircraft, and pilot UAVs. Communication satellites, deep-space probes, and many medical instruments would have been nearly impossible to create without embedded software.
标签： familiarity programming experience dominant
上传时间： 2013-12-11
上传用户：362279997
学习Direct3D中的2D-Focus.On.2D.in.Direct3D.-.fly
标签： Direct3D D-Focus Direct fly
上传时间： 2013-08-04
上传用户：eeworm
游戏开发大全-game.programming.all.in.one
标签： programming game all one
上传时间： 2013-06-29
上传用户：eeworm
