該文檔為GNSS軟件接收機關鍵技術研究及實現講解文檔，是一份很不錯的參考資料，具有較高參考價值，感興趣的可以下載看看………………
標簽： gnss
上傳時間： 2022-03-06
上傳用戶：
SKYLAB無線模塊GNSS/WiFi/藍牙模塊應用解決方案
上傳時間： 2022-07-05
上傳用戶：
隨著中國二代導航系統的建設，衛星導航的應用將普及到各個行業，具有自主知識產權的衛星導航接收機的研究與設計是該領域的一個研究熱點。在接收機的設計中，對于成熟技術將利用ASIC芯片進行批量生產，該芯片是專用芯片，一旦制造成型不能改變。但是對于正在研究的接收機技術，特別是在需要利用接收機平臺進行提高接收機性能研究時，利用FPGA通用可編程門陣列芯片是非常方便的。在FPGA上的研究成果，一旦成熟可以很方便的移植到ASIC芯片，進行批量生產。本課題就是基于FPGA研究GPS并行捕獲技術的硬件電路，著重進行了其中一個捕獲通道的設計和實現。 GPS信號捕獲時間是影響GPS接收機性能的一個關鍵因素，尤其是在高動態和實時性要求高的應用中或者對弱GPS信號的捕獲方面。因此，本文在滑動相關法基礎上引出了基于FFT的并行快速捕獲方法，采用自頂向下的方法對系統進行總體功能劃分和結構設計，并采用自底向上的方法對系統進行功能實現和驗證。 本課題以Xilinx公司的Spartan3E開發板為硬件開發平臺，以ISE9.2i為軟件開發平臺，采用Verilog HDL編程實現該系統。并利用Nemerix公司的GPS射頻芯片NJ1006A設計制作了GPS中頻信號產生平臺。該平臺可實時地輸出采樣頻率為16.367MHz的GPS數字中頻信號。 本課題主要是基于采樣率變換和FFT實現對GPS C/A碼的捕獲。該算法利用平均采樣的方法，將信號的采樣率降低到1.024 MHz，在低采樣率下利用成熟的1024點FFT IP核對C/A碼進行粗捕，給出GPS信號的碼相位(精度大約為1/4碼片)和載波的多普勒頻率，符合GPS后續跟蹤的要求。 同時，由于FFT算法是以資源換取時間的方法來提高GPS捕獲速度的，所以在設計時，合理地采用FPGA設計思想與技巧優化系統?；趯嵱眯缘囊?，詳細的給出了基于FFT的GPS并行捕獲各個模塊的實現原理、實現結構以及仿真結果。并達到降低系統硬件資源，能夠快速、高效地實現對GPS C/A碼捕獲的要求。 本研究是導航研究所承擔的國家863課題“利用多徑信號提高GNSS接收機性能的新技術研究”中關于接收機信號捕獲算法的一部分，對接收機的設計具有一定的參考價值。
上傳時間： 2013-07-22
上傳用戶：user08x
隨著現代信息系統發展，網絡系統尤其是分布式系統日益廣泛地用于各個行業和領域，其中很多的關鍵應用需要基于時間同步進行。傳統采用精準時鐘對設備物理時鐘進行精準調節以達到時鐘同步的方式，以及單純的在局域網內部通過相關時間協議進行時間同步的方式，由于受諸多限制，不能很好地解決分布式精確時鐘同步的問題。然而人們對分布式時間精準度和時間同步的精確度要求越來越高，新型分布式網絡時間同步研究成為一個需要亟待解決的關鍵性問題。既有工程應用價值，也有一定的理論意義。 首先從分布式系統應用的角度出發，首先對GNSS衛星授時、NTP協議、嵌入式系統及uClinux操作系統等理論和技術進行了闡述。重點討論了如何解決分布式系統中的精確授時與同步問題的必要性和工程意義，分析了GNSS衛星授時特點和NTP網絡協議的機制。 其次在充分考慮到網絡同步實時性要求高的特點的基礎上，提出了一種基于GNSS的嵌入式NTP授時服務器的設計架構，對各主要模塊的功能、結構和工作原理進行了功能和性能分析。硬件具體以32位ARMS3C44B0X作為硬件控制核心的微處理器，開發了具有多通信端口的應用電路主板，并集成了GNSS衛星通信模塊。 再次在軟件方面具體對uClinux操作系統底層接口進行了較為深入的分析，在所設計的服務器硬件平臺上移植了uClinux嵌入式操作系統及相關的驅動程序，并采用模塊化的設計思想進行了NTP應用程序的設計與集成，實現了NTP協議的編譯和NTP授時服務，其中對NTP協議主要參數和具體工作過程進行了系統性分析和設置應用。 最后在獲取精準的系統統一時鐘、通過NTP協議提供授時服務的基礎上，結合實際在人工影響天氣通信指揮系統中具體應用，實現了分布式人工降雨火箭彈發射點按命令精確同步進行發射的應用集成。初步測試表明，本文所設計的授時服務器應用情況良好，實現了不同層次分布式應用對于時間精準同步的高要求。
上傳時間： 2013-04-24
上傳用戶：ouyangtongze
CAN測量與標定下位機程序及詳細文檔。can標定C語言實現-CAN Measurement and Calibration under the crew detailed procedures and
標簽： ccp
上傳時間： 2013-05-19
上傳用戶：hrzx1234
Angle measurement is frequently required in both automotive and industrial applications. Contactl
上傳時間： 2013-05-18
上傳用戶：cuiqiang
High input impedance and a wide input range are twohighly desirable features in a precision analog-to-digitalconverter, and the LTC®2449 delta-sigma ADC has both.With just a few external components, the LTC2449 formsan exceptional measurement system with very high inputimpedance and an input range that extends 300mV beyondthe supply rails.
上傳時間： 2013-11-02
上傳用戶：ywcftc277
Control systems are becoming increasingly dependent on digital processing and so require sensors able to provide direct digital inputs. Sensors based on time measurement, having outputs based on a frequency or phase, have an advantage over conventional analogue sensors in that their outputs can be measured directly in digital systems by pulse counting.
上傳時間： 2013-10-08
上傳用戶：wuyuying
ANALOG INPUT BANDWIDTH is a measure of the frequencyat which the reconstructed output fundamental drops3 dB below its low frequency value for a full scale input. Thetest is performed with fIN equal to 100 kHz plus integer multiplesof fCLK. The input frequency at which the output is −3dB relative to the low frequency input signal is the full powerbandwidth.APERTURE JITTER is the variation in aperture delay fromsample to sample. Aperture jitter shows up as input noise.APERTURE DELAY See Sampling Delay.BOTTOM OFFSET is the difference between the input voltagethat just causes the output code to transition to the firstcode and the negative reference voltage. Bottom Offset isdefined as EOB = VZT–VRB, where VZT is the first code transitioninput voltage and VRB is the lower reference voltage.Note that this is different from the normal Zero Scale Error.CONVERSION LATENCY See PIPELINE DELAY.CONVERSION TIME is the time required for a completemeasurement by an analog-to-digital converter. Since theConversion Time does not include acquisition time, multiplexerset up time, or other elements of a complete conversioncycle, the conversion time may be less than theThroughput Time.DC COMMON-MODE ERROR is a specification which appliesto ADCs with differential inputs. It is the change in theoutput code that occurs when the analog voltages on the twoinputs are changed by an equal amount. It is usually expressed in LSBs.
上傳時間： 2013-11-12
上傳用戶：pans0ul
高速數字系統設計下載pdf:High-Speed Digital SystemDesign—A Handbook ofInterconnect Theory and DesignPracticesStephen H. HallGarrett W. HallJames A. McCallA Wiley-Interscience Publication JOHN WILEY & SONS, INC.New York • Chichester • Weinheim • Brisbane • Singapore • TorontoCopyright © 2000 by John Wiley & Sons, Inc.speeddigital systems at the platform level. The book walks the reader through everyrequired concept, from basic transmission line theory to digital timing analysis, high-speedmeasurement techniques, as well as many other topics. In doing so, a unique balancebetween theory and practical applications is achieved that will allow the reader not only tounderstand the nature of the problem, but also provide practical guidance to the solution.The level of theoretical understanding is such that the reader will be equipped to see beyondthe immediate practical application and solve problems not contained within these pages.Much of the information in this book has not been needed in past digital designs but isabsolutely necessary today. Most of the information covered here is not covered in standardcollege curricula, at least not in its focus on digital design, which is arguably one of the mostsignificant industries in electrical engineering.The focus of this book is on the design of robust high-volume, high-speed digital productssuch as computer systems, with particular attention paid to computer busses. However, thetheory presented is applicable to any high-speed digital system. All of the techniquescovered in this book have been applied in industry to actual digital products that have beensuccessfully produced and sold in high volume.Practicing engineers and graduate and undergraduate students who have completed basicelectromagnetic or microwave design classes are equipped to fully comprehend the theorypresented in this book. At a practical level, however, basic circuit theory is all thebackground required to apply the formulas in this book.
上傳時間： 2013-10-26
上傳用戶：縹緲
