鎖定放大是微弱信號檢測的重要手段。基于相關檢測理論，利用開關電容的開關實現鎖定放大器中乘法器的功能，提出開關電容和積分器相結合以實現相關檢測的方法，并設計出一種鎖定放大器。該鎖定放大器將微弱信號轉化為與之相關的方波，通過后續電路得到正比于被測信號的直流電平，為后續采集處理提供方便。測量數據表明鎖定放大器前級可將10-6 A的電流轉換為10-1 V的電壓，后級通過帶通濾波器級聯可將信號放大1×105倍。該方法在降低噪聲的同時，可對微弱信號進行放大，線性度較高、穩定性較好。 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.
上傳時間： 2013-11-29
上傳用戶：黑漆漆
畢業設計 USB TO Gigabit LAN 網卡 隨著網絡技術飛速發展，多媒體的應用越來越多，人們對網絡的要求也越來越高，為了適應市場的需求，網卡出現了。它以其結構簡單、成本低廉、兼容性強等諸多的優越性得到了廣泛的應用。由于網絡的應用越來越廣泛，網卡的應用也越來越多、功能越來越強大。開始時由于技術方面的限制，網卡只有10Mbps的吞吐量，由于網絡技術的發展，100Mbps吞吐量的網卡開始在市場上得到廣泛的應用。而現在1000Mbps吞吐量的網卡的出現又給網絡的傳輸帶來了新的活力。 論文中主要闡述了基于以太網的USB TO Gigabit LAN網卡的設計與制作。論文首先對以太網進行了介紹，緊接著講了網卡的基本知識。隨后又對USB TO Gigabit LAN網卡的電路設計和制作進行了詳細的描述。論文還包括了USB TO Gigabit LAN網卡的調試等內容。
上傳時間： 2014-12-02
上傳用戶：wab1981
以C8051F020為核心處理器，設計無線傳感器網絡數據采集系統。系統采用SZ05-ADV型無線通訊模塊組建Zigbee無線網絡，結合嵌入式系統的軟硬件技術，完成終端節點的8路傳感器信號的數據采集。現場8路信號通過前端處理后，分別送入C8051F020的12位A/D轉換器進行轉換。經過精確處理、存儲后的現場數據，通過Zigbee無線網絡傳送到上位機，系統可達到汽車試驗中無線測試的目的。 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.
標簽： C8051F020 Zigbee 汽車測試 系統設計
上傳時間： 2013-11-23
上傳用戶：dsgkjgkjg
介紹一種基于CAN總線的牽引變電站自動化系統通訊規約的設計，CAN通訊規約采用標準幀，報文采用主動發送和發送查詢兩種處理形式。該設計在城市輕軌與地鐵牽引變電站中的應用表明：可實現間隔層和通訊處理層的數據快速、可靠的交換，提高牽引變電站的安全性和穩定性 。 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.
上傳時間： 2013-11-07
上傳用戶：bs2005
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.
上傳時間： 2013-10-26
上傳用戶：fengweihao158@163.com
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.
上傳時間： 2013-11-09
上傳用戶：geshaowei
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.
標簽： Spartan-DSP Virtex FPGAs Ap
上傳時間： 2013-10-23
上傳用戶：raron1989
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.
上傳時間： 2013-11-14
上傳用戶：yeling1919
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.
上傳時間： 2013-11-07
上傳用戶：xy@1314
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.
上傳時間： 2014-12-28
上傳用戶：270189020
