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  • 基于开关电容技术的锁定放大器设计

    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.

    标签: 开关电容 锁定放大器

    上传时间: 2013-11-29

    上传用户:黑漆漆

  • USB TO Gigabit LAN网卡的设计与制作

    毕业设计 USB TO Gigabit LAN 网卡 随着网络技术飞速发展,多媒体的应用越来越多,人们对网络的要求也越来越高,为了适应市场的需求,网卡出现了。它以其结构简单、成本低廉、兼容性强等诸多的优越性得到了广泛的应用。由于网络的应用越来越广泛,网卡的应用也越来越多、功能越来越强大。开始时由于技术方面的限制,网卡只有10Mbps的吞吐量,由于网络技术的发展,100Mbps吞吐量的网卡开始在市场上得到广泛的应用。而现在1000Mbps吞吐量的网卡的出现又给网络的传输带来了新的活力。 论文中主要阐述了基于以太网的USB TO Gigabit LAN网卡的设计与制作。论文首先对以太网进行了介绍,紧接着讲了网卡的基本知识。随后又对USB TO Gigabit LAN网卡的电路设计和制作进行了详细的描述。论文还包括了USB TO Gigabit LAN网卡的调试等内容。

    标签: Gigabit USB LAN TO

    上传时间: 2014-12-02

    上传用户:wab1981

  • 基于C8051F020和Zigbee的汽车测试系统设计

    以C8051F020为核心处理器,设计无线传感器网络数据采集系统。系统采用SZ05-ADV型无线通讯模块组建Zigbee无线网络,结合嵌入式系统的软硬件技术,完成终端节点的8路传感器信号的数据采集。现场8路信号通过前端处理后,分别送入C8051F020的12位A/D转换器进行转换。经过精确处理、存储后的现场数据,通过Zigbee无线网络传送到上位机,系统可达到汽车试验中无线测试的目的。 Abstract:  This paper designs a wireless sensor network system for data acquisition with C8051F020 as core processors.The system used SZ05-ADV wireless communication module,set up a Zigbee wireless network, combined with hardware and software technologies of embedded systems,completed the end-node 8-locale sensor signal data acquisition.Eight locale signals were sent separately into the 12-bit ADC of C8051F020 for conversion through front treatment.After accurate processing and storage,the locale data was transmitted to the host computer through Zigbee wireless.The system achieves the purpose of wireless testing in vehicle trial.

    标签: C8051F020 Zigbee 汽车测试 系统设计

    上传时间: 2013-11-23

    上传用户:dsgkjgkjg

  • 基于CAN总线的综自通讯规约设计

    介绍一种基于CAN总线的牵引变电站自动化系统通讯规约的设计,CAN通讯规约采用标准帧,报文采用主动发送和发送查询两种处理形式。该设计在城市轻轨与地铁牵引变电站中的应用表明:可实现间隔层和通讯处理层的数据快速、可靠的交换,提高牵引变电站的安全性和稳定性 。 Abstract:  This paper firstly presents a kind of design dealing with communicational protocol to the traction substation automation system based on CAN bus,and then comes up with the ideas that all frames of CAN communicational protocol should adopt the standard frame,and that messages be processed by two ways:sending initiatively and sending quiries.Subway and light rail application shows that the use of the CAN bus is possible to exchange data quickly and reliably between the layers of the middle and the communicational processing,hence to improve the safety and stability of traction substations.

    标签: CAN 总线 通讯规约

    上传时间: 2013-11-07

    上传用户:bs2005

  • FET430PIF自制资料

    The MSP-FET430PIF is a Parallel Port interface (does not include target board) that is used to program and debug MSP430 FET tools and test boards through the JTAG interface. This interface is included in our FET tools, but sold without the development board. This interface uses a Parallel PC Port to communicate to the Debugger Software (IAR Kickstart software included) running on the PC. The interface uses the standard 14 pin header to communicate to the MSP430 device using the standard JTAG protocol. The flash memory can be erased and programmed in seconds with only a few keystrokes, and since the MSP430 flash is extremely low power, no external power supply is required. The tool has an integrated software environment and connects directly to the PC which greatly simplifies the set-up and use of the tool. The flash development tool supports development with all MSP430 flash parts. Features MSP430 debugging interface to connect a MSP430-Flash-device to a Parallel port on a PC Supports JTAG debug protocol (NO support for Spy-Bi-Wire (2-wire JTAG) debug protocol, Spy-Bi-Wire (2-wire JTAG) is supported by MSP-FET430UIF) Parallel Port cable and a 14-conductor target cable Full documentation on CD ROM Integrated IAR Kickstart user interface which includes: Assembler Linker Limulator Source-level debugger Limited C-compiler Technical specifications: Backwardly compatable with existing FET tool boards.

    标签: FET 430 PIF

    上传时间: 2013-10-26

    上传用户:fengweihao158@163.com

  • LPC1700以太网MIIM接口应用笔记

    The LPC1700 Ethernet block contains a full featured 10 Mbps or 100 Mbps Ethernet MAC (Media Access Controller) designed to provide optimized performance through the use of DMA hardware acceleration. Features include a generous suite of control registers, half or full duplex operation, flow control, control frames, hardware acceleration for transmit retry, receive packet filtering and wake-up on LAN activity. Automatic frame transmission and reception with Scatter-Gather DMA off-loads many operations from the CPU.

    标签: 1700 MIIM LPC 以太网

    上传时间: 2013-11-09

    上传用户:geshaowei

  • Virtex-5, Spartan-DSP FPGAs Ap

    Virtex-5, Spartan-DSP FPGAs Application Note This application note demonstrates how efficient implementations of Digital Up Converters(DUC) and Digital Down Converters (DDC) can be done by leveraging the Xilinx DSP IPportfolio for increased productivity and reduced time to development. Step-by-step instruction is given on how to perform system-level trade off analysis and develop the most efficient FPGA implementation, thus allowing engineers a flexible, low-cost and low-power alternative to ASSP technologies.

    标签: Spartan-DSP Virtex FPGAs Ap

    上传时间: 2013-10-23

    上传用户:raron1989

  • TPS65930 TPS65920与OMAP3530硬件连接

    This document describes the system hardware implementation for the OMAP3530 processor and theTPS65930/20 companion power integrated circuit (IC). The document concentrates on the powerconnectivity for the processor and the companion power IC. The document also briefly explains someother specifics related to power, such as the boot modes and the power-up sequence.

    标签: TPS 65930 65920 3530

    上传时间: 2013-11-14

    上传用户:yeling1919

  • XL6003 300KHz 36V Boost 3W LED

    The XL6003 regulator is fixed frequency PWM Boost (step-up) DC/DC converter, capable ofdriving 1050mA load current with excellent line and load regulation. The regulator is simple to use because it includes internal frequency compensation and a fixed-frequency oscillator so that it requires a minimum number of external components to work. The XL6003 could directly drive 5~10 3W LED units at VIN=12V.

    标签: Boost 6003 300 36V

    上传时间: 2013-11-07

    上传用户:xy@1314

  • PCA9547 8 channel I2C bus mult

    The PCA9547 is an octal bidirectional translating multiplexer controlled by the I2C-bus.The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Only oneSCx/SDx channel can be selected at a time, determined by the contents of theprogrammable control register. The device powers up with Channel 0 connected, allowingimmediate communication between the master and downstream devices on that channel.

    标签: channel 9547 mult PCA

    上传时间: 2014-12-28

    上传用户:270189020