·詳細說明：包含了從MPEG4的視頻解碼到H.264的視頻編碼部分的源代碼，不包括音頻部分的編解碼- Contained has decoded from the MPEG4 video frequency to the H.264 video frequency code partial sources code, partial did not arrange including the aud
·詳細說明：提供了目前最全面的音頻,視頻的編碼和解碼庫,包括G.711,G.726,AMR,MP3,H.261,H.263,MPEG-1,MPEG-2,MPEG-4,H.264,使用MMX匯編優化,效率非常高。可以直接加入到自己的工程中使用，非常方便。- Has provided the present most comprehensive audio frequency, the video fr
·詳細說明：MPEG4流媒體的視頻傳輸和運程播放代碼，VC平臺-MPEG4 flows the media the video frequency to transmit and to haul the broadcast code, the VC platform 相關函數/類: CreateEvent CloseHandle ResetEvent WaitForSingleObject
·詳細說明：MPEG2視頻編解碼程序-mpeg2 video frequency arranges the decoding procedure 文件列表: mpeg2視頻編解碼器 .................\bin .................\...\emu387 .................\...\mpeg2dec.
用fpga實現的DA轉換器，有說明和源碼，VDHL文件。\\r\\nA PLD Based Delta-Sigma DAC\\r\\nDelta-Sigma modulation is the simple, yet powerful,\\r\\ntechnique responsible for the extraordinary\\r\\nperformance and low cost of today s audio CD\\r\\nplayers. The simplest Delta-Sigm
為了滿足現代高速通信中頻率快速轉換的需求，基于坐標旋轉數字計算（CORDIC，Coordinate Rotation Digital Computer）算法完成正交直接數字頻率合成（ODDFS，Orthogonal Direct Digital Frequency Synthesizer）電路設計方案。采用MATLAB和Xilinx System Generator開發工具搭建電路的系統模型，通過現場可編程門陣列（FPGA，Field Programmable Gate Array）完成電路的寄存器傳輸級（RTL，Register Transfer Level）驗證，仿真結果表明電路設計具有很高的有效性和可行性。
微弱信號檢測裝置
四川理工學院 劉鵬飛、梁天德、曾學明
摘要：
本設計以TI的Launch Pad為核心板，采用鎖相放大技術設計并制作了一套微弱信號檢測裝置，用以檢測在強噪聲背景下已知頻率微弱正弦波信號的幅度值，并在液晶屏上數字顯示出所測信號相應的幅度值。實驗結果顯示其抗干擾能力強，測量精度高。
關鍵詞：強噪聲；微弱信號；鎖相放大；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
隨著現代科學技術的發展，在科研與生產過程中人們越來越需要從復雜高強度的噪聲中檢測出有用的微弱信號，因此對微弱信號的檢測成為當前科研的熱點。微弱信號并不意味著信號幅度小，而是指被噪聲淹沒的信號，“微弱”也僅是相對于噪聲而言的。只有在有效抑制噪聲的條件下有選擇的放大微弱信號的幅度，才能提取出有用信號。微弱信號檢測技術的應用相當廣泛，在生物醫學、光學、電學、材料科學等相關領域顯得愈發重要。
2、方案論證
針對微弱信號的檢測的方法有很多，比如濾波法、取樣積分器、鎖相放大器等。下面就針對這幾種方法做一簡要說明。
方案一：濾波法。
在大部分的檢測儀器中都要用到濾波方法對模擬信號進行一定的處理，例如隔離直流分量，改善信號波形，防止離散化時的波形混疊，克服噪聲的不利影響，提高信噪比等。常用的噪聲濾波器有：帶通、帶阻、高通、低通等。但是濾波方法檢測信號不能用于信號頻譜與噪聲頻譜重疊的情況，有其局限性。雖然可以對濾波器的通頻帶進行調節，但其噪聲抑制能力有限，同時其準確性與穩定性將大打折扣。
Abstract: Most magnetic read head data sheets do not fully specify the frequency-dependent components andare often vague when specifying other key parameters. In some cases, the specifications of two very similarheads from two different manufacturers might be quite different in terms of parameters specified and omitted.The limitations in the data sheets make designing an optimum card reading system unnecessarily difficult andtime consuming. This document outlines a strategy to overcome the above shortcomings and offers guidelinesto overcome the noise issues.
The MAX5713/MAX5714/MAX5715 4-channel, low-power,8-/10-/12-bit, voltage-output digital-to-analog converters(DACs) include output buffers and an internal referencethat is selectable to be 2.048V, 2.500V, or 4.096V. TheMAX5713/MAX5714/MAX5715 accept a wide supplyvoltage range of 2.7V to 5.5V with extremely low power(3mW) consumption to accommodate most low-voltageapplications. A precision external reference input allowsrail-to-rail operation and presents a 100kI (typ) load toan external reference.
