The exacting technological demands created byincreasing bandwidth requirements have given riseto significant advances in FPGA technology thatenable engineers to successfully incorporate highspeedI/O interfaces in their designs. One aspect ofdesign that plays an increasingly important role isthat of the FPGA package. As the interfaces get fasterand wider, choosing the right package has becomeone of the key considerations for the systemdesigner.
波長信號的解調(diào)是實現(xiàn)光纖光柵傳感網(wǎng)絡的關鍵，基于現(xiàn)有的光纖光柵傳感器解調(diào)方法，提出一種基于FPGA的雙匹配光纖光柵解調(diào)方法，此系統(tǒng)是一種高速率、高精度、低成本的解調(diào)系統(tǒng)，并且通過引入雙匹配光柵有效地克服了雙值問題同時擴大了檢測范圍。分析了光纖光柵的測溫原理并給出了該方案軟硬件設計，綜合考慮系統(tǒng)的解調(diào)精度和FPGA的處理速度給出了基于拉格朗日的曲線擬合算法。
Abstract:
Sensor is one of the most important application of the fiber grating. Wavelength signal demodulating is the key techniques to carry out fiber grating sensing network， based on several existing methods of fiber grating sensor demodulation inadequate， a two-match fiber grating demodulation method was presented. This system is a high-speed， high precision， low-cost demodulation system. And by introducing a two-match grating effectively overcomes the problem of double value while expands the scope of testing. This paper analyzes the principle of fiber Bragg grating temperature and gives the software and hardware design of the program. Considering the system of demodulation accuracy and processing speed of FPGA，this paper gives the curve fitting algorithm based on Lagrange.
磁芯電感器的諧波失真分析 摘 要：簡述了改進鐵氧體軟磁材料比損耗系數(shù)和磁滯常數(shù)ηB，從而降低總諧波失真THD的歷史過程，分析了諸多因數(shù)對諧波測量的影響，提出了磁心性能的調(diào)控方向。 關鍵詞：比損耗系數(shù)， 磁滯常數(shù)ηB ，直流偏置特性DC-Bias，總諧波失真THD Analysis on THD of the fer rite co res u se d i n i nductancShi Yan Nanjing Finemag Technology Co. Ltd., Nanjing 210033 Abstract: Histrory of decreasing THD by improving the ratio loss coefficient and hysteresis constant of soft magnetic ferrite is briefly narrated. The effect of many factors which affect the harmonic wave testing is analysed. The way of improving the performance of ferrite cores is put forward. Key words: ratio loss coefficient，hysteresis constant，DC-Bias，THD 近年來，變壓器生產(chǎn)廠家和軟磁鐵氧體生產(chǎn)廠家，在電感器和變壓器產(chǎn)品的總諧波失真指標控制上，進行了深入的探討和廣泛的合作，逐步弄清了一些似是而非的問題。從工藝技術上采取了不少有效措施，促進了質(zhì)量問題的迅速解決。本文將就此熱門話題作一些粗淺探討。 一、 歷史回顧 總諧波失真（Total harmonic distortion） ，簡稱THD，并不是什么新的概念，早在幾十年前的載波通信技術中就已有嚴格要求<1>。1978年郵電部公布的標準YD/Z17－78“載波用鐵氧體罐形磁心”中，規(guī)定了高μQ材料制作的無中心柱配對罐形磁心詳細的測試電路和方法。如圖一電路所示，利用LC組成的150KHz低通濾波器在高電平輸入的情況下測量磁心產(chǎn)生的非線性失真。這種相對比較的實用方法，專用于無中心柱配對罐形磁心的諧波衰耗測試。 這種磁心主要用于載波電報、電話設備的遙測振蕩器和線路放大器系統(tǒng)，其非線性失真有很嚴格的要求。
圖中 ZD —— QF867 型阻容式載頻振蕩器，輸出阻抗 150Ω， Ld47 —— 47KHz 低通濾波器，阻抗 150Ω，阻帶衰耗大于61dB， Lg88 ——并聯(lián)高低通濾波器，阻抗 150Ω，三次諧波衰耗大于61dB Ld88 ——并聯(lián)高低通濾波器，阻抗 150Ω，三次諧波衰耗大于61dB FD —— 30～50KHz 放大器， 阻抗 150Ω， 增益不小于 43 dB，三次諧波衰耗b3(0)≥91 dB, DP —— Qp373 選頻電平表，輸入高阻抗， L ——被測無心罐形磁心及線圈， C ——聚苯乙烯薄膜電容器CMO-100V-707APF±0.5%,二只。
測量時，所配用線圈應用絲包銅電磁線SQJ9×0.12(JB661-75)在直徑為16.1mm的線架上繞制 120 匝， （線架為一格） ， 其空心電感值為 318μH（誤差1％） 被測磁心配對安裝好后，先調(diào)節(jié)振蕩器頻率為 36.6～40KHz， 使輸出電平值為+17.4 dB， 即選頻表在 22′端子測得的主波電平 （P2）為+17.4 dB，然后在33′端子處測得輸出的三次諧波電平（P3）， 則三次諧波衰耗值為：b3(+2)= P2+S+ P3 式中：S 為放大器增益dB 從以往的資料引證， 就可以發(fā)現(xiàn)諧波失真的測量是一項很精細的工作，其中測量系統(tǒng)的高、低通濾波器，信號源和放大器本身的三次諧波衰耗控制很嚴，阻抗必須匹配，薄膜電容器的非線性也有相應要求。濾波器的電感全由不帶任何磁介質(zhì)的大空心線圈繞成，以保證本身的“潔凈” ，不至于造成對磁心分選的誤判。 為了滿足多路通信整機的小型化和穩(wěn)定性要求， 必須生產(chǎn)低損耗高穩(wěn)定磁心。上世紀 70 年代初，1409 所和四機部、郵電部各廠，從工藝上改變了推板空氣窯燒結，出窯后經(jīng)真空罐冷卻的落后方式，改用真空爐，并控制燒結、冷卻氣氛。技術上采用共沉淀法攻關試制出了μQ乘積 60 萬和 100 萬的低損耗高穩(wěn)定材料，在此基礎上，還實現(xiàn)了高μ7000～10000材料的突破，從而大大縮短了與國外企業(yè)的技術差異。當時正處于通信技術由FDM（頻率劃分調(diào)制）向PCM（脈沖編碼調(diào)制） 轉換時期， 日本人明石雅夫發(fā)表了μQ乘積125 萬為 0.8×10 ，100KHz）的超優(yōu)鐵氧體材料<3>，其磁滯系數(shù)降為優(yōu)鐵
The revolution of automation on factory floors is a key driver for the seemingly insatiable demand for higher productivity， lower total cost of ownership，and high safety. As a result， industrial applications drive an insatiable demand of higher data bandwidth and higher system-level performance.
This white paper describes the trends and challenges seen by designers and how FPGAs enable solutions to meet their stringent design goals.
Have you had the exasperating experience of a laptop orPDA defi antly not responding to your commands? Youfrantically press key after key, but to no avail. As hopeturns to anger (but just before you throw the company’slaptop through the window) you slam your fi nger againstthe on/off power button. Ten seconds later, your laptopfi nally surrenders and the screen goes black in a highpitched whimper.
在Multisim 10軟件環(huán)境下，設計一種由運算放大器構成的精確可控矩形波信號發(fā)生器，結合系統(tǒng)電路原理圖重點闡述了各參數(shù)指標的實現(xiàn)與測試方法。通過改變RC電路的電容充、放電路徑和時間常數(shù)實現(xiàn)了占空比和頻率的調(diào)節(jié)，通過多路開關投入不同數(shù)值的電容實現(xiàn)了頻段的調(diào)節(jié)，通過電壓取樣和同相放大電路實現(xiàn)了輸出電壓幅值的調(diào)節(jié)并提高了電路的帶負載能力，可作為頻率和幅值可調(diào)的方波信號發(fā)生器。Multisim 10仿真分析及應用電路測試結果表明，電路性能指標達到了設計要求。
Abstract:
Based on Multisim 10， this paper designed a kind of rectangular-wave signal generator which could be controlled exactly composed of operational amplifier， the key point was how to implement and test the parameter indicators based on the circuit diagram. The duty and the frequency were adjusted by changing the time constant and the way of charging and discharging of the capacitor， the width of frequency was adjusted by using different capacitors provided with multiple switch， the amplitude of output voltage was adjusted by sampling voltage and using in-phase amplifier circuit，the ability of driving loads was raised， the circuit can be used as squarewave signal generator whose frequency and amplitude can be adjusted. The final simulation results of Multisim 10 and the tests of applicable circuit show that the performance indicators of the circuit meets the design requirements.
利用EZ-USB接口芯片AN2131Q實現(xiàn)了基于TMS320C5409的水聲信號采集及混沌特性研究系統(tǒng)中的高速數(shù)據(jù)通信，提出了一種采用FIFO緩存芯片實現(xiàn)AN2131Q與TMS320C5409的連接方法，深入研究了EZ-USB序列接口芯片的固件、設備驅動和用戶程序開發(fā)過程。關鍵詞：AN2131Q; TMS320C5409; IDT72V02；數(shù)據(jù)通信ABSTRACT: Using AN2131Q as the control chip, the communication between DSP and PC in the underwater acoustic signal acquisition and chaotic characteristics study system is realized. The method is proposed that using FIFO to realize the connectivity between AN2131Q and TMS320C5409. The development of programming Firmware、device driver and user application are thoroughly researched.Key words: AN2131Q; TMS320C5409; IDT72V02; data communication
This hands-on, one-stop guide delivers the focused, streamlined direction you need to get your Web solutions up and running quickly. Zero in on key ASP.NET configuration details and techniques using quick-reference tables, lists, coding and more.
