同步技术是跳频通信系统的关键技术之一，尤其是在快速跳频通信系统中，常规跳频通信通过同步字头携带相关码的方法来实现同步，但对于快跳频来说，由于是一跳或者多跳传输一个调制符号，难以携带相关码。对此引入双跳频图案方法，提出了一种适用于快速跳频通信系统的同步方案。采用短码携带同步信息，克服了快速跳频难以携带相关码的困难。分析了同步性能，仿真结果表明该方案同步时间短、虚警概率低、捕获概率高，同步性能可靠。 Abstract: Synchronization is one of the key techniques to frequency-hopping communication system， especially in the fast frequency hopping communication system. In conventional frequency hopping communication systems， synchronization can be achieved by synchronization-head which can be used to carry the synchronization information， but for the fast frequency hopping， Because modulation symbol is transmitted by per hop or multi-hop， it is difficult to carry the correlation code. For the limitation of fast frequency hopping in carrying correlation code， a fast frequency-hopping synchronization scheme with two hopping patterns is proposed. The synchronization information is carried by short code， which overcomes the difficulty of correlation code transmission in fast frequency-hopping. The performance of the scheme is analyzed， and simulation results show that the scheme has the advantages of shorter synchronization time， lower probability of false alarm， higher probability of capture and more reliable of synchronization.
上传时间： 2013-11-23
上传用户：mpquest
Single-Ended and Differential S-Parameters Differential circuits have been important incommunication systems for many years. In the past,differential communication circuits operated at lowfrequencies, where they could be designed andanalyzed using lumped-element models andtechniques. With the frequency of operationincreasing beyond 1GHz, and above 1Gbps fordigital communications, this lumped-elementapproach is no longer valid, because the physicalsize of the circuit approaches the size of awavelength.Distributed models and analysis techniques are nowused instead of lumped-element techniques.Scattering parameters, or S-parameters, have beendeveloped for this purpose [1]. These S-parametersare defined for single-ended networks. S-parameterscan be used to describe differential networks, but astrict definition was not developed until Bockelmanand others addressed this issue [2]. Bockelman’swork also included a study on how to adapt single-ended S-parameters for use with differential circuits[2]. This adaptation, called “mixed-mode S-parameters,” addresses differential and common-mode operation, as well as the conversion betweenthe two modes of operation.This application note will explain the use of single-ended and mixed-mode S-parameters, and the basicconcepts of microwave measurement calibration.
上传时间： 2014-03-25
上传用户：yyyyyyyyyy
Agilent AN 154 S-Parameter Design Application Note S参数的设计与应用 The need for new high-frequency, solid-state circuitdesign techniques has been recognized both by microwaveengineers and circuit designers. These engineersare being asked to design solid state circuitsthat will operate at higher and higher frequencies.The development of microwave transistors andAgilent Technologies’ network analysis instrumentationsystems that permit complete network characterizationin the microwave frequency rangehave greatly assisted these engineers in their work.The Agilent Microwave Division’s lab staff hasdeveloped a high frequency circuit design seminarto assist their counterparts in R&D labs throughoutthe world. This seminar has been presentedin a number of locations in the United States andEurope.From the experience gained in presenting this originalseminar, we have developed a four-part videotape, S-Parameter Design Seminar. While the technologyof high frequency circuit design is everchanging, the concepts upon which this technologyhas been built are relatively invariant.The content of the S-Parameter Design Seminar isas follows:
标签： S参数
上传时间： 2013-12-19
上传用户：aa54
It would not be an exaggeration to say that semiconductor devices have transformed humanlife. From computers to communications to internet and video games these devices and the technologies they have enabled have expanded human experience in a way that is unique in history. Semiconductor devices have exploited materials, physics and imaginative applications to spawn new lifestyles. Of course for the device engineer, in spite of the advances, the challenges of reaching higher frequency, lower power consumption, higher power generation etc.
上传时间： 2013-10-28
上传用户：songnanhua
怎样使用Nios II处理器来构建多处理器系统 Chapter 1. Creating Multiprocessor Nios II Systems Introduction to Nios II Multiprocessor Systems . . . . . . . . . . . . . . 1–1 Benefits of Hierarchical Multiprocessor Systems . . . . . . . . . . . . . . . 1–2 Nios II Multiprocessor Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2 Multiprocessor Tutorial Prerequisites . . . . . . . . . . . . . . . . . . . . . . . 1–3 Hardware Designs for Peripheral Sharing . . . . . . . . . . . .. . . . . . . . 1–3 Autonomous Multiprocessors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3 Multiprocessors that Share Peripherals . . . . . . . . . . . . . . . . . . . . . . 1–4 Sharing Peripherals in a Multiprocessor System . . . . . . . . . . . . . . . . . 1–4 Sharing Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–6 The Hardware Mutex Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7 Sharing Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 1–8 Overlapping Address Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–8 Software Design Considerations for Multiple Processors . . .. . . . . 1–9 Program Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–9 Boot Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1–13 Debugging Nios II Multiprocessor Designs . . . . . . . . . . . . . . . . 1–15 Design Example: The Dining Philosophers’ Problem . . . . .. . . 1–15 Hardware and Software Requirements . . . . . . . . . . . . . . . .. . . 1–16 Installation Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–17 Creating the Hardware System . . . . . . . . . . . . . . .. . . . . . 1–17 Getting Started with the multiprocessor_tutorial_start Design Example 1–17 Viewing a Philosopher System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–18 Philosopher System Pipeline Bridges . . . . . . . . . . . . . . . . . . . . . 1–19 Adding Philosopher Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . 1–21 Connecting the Philosopher Subsystems . . . . . . . . . . . . .. . . . . 1–22 Viewing the Complete System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–27 Generating and Compiling the System . . . . . . . . . . . . . . . . . .. 1–28
上传时间： 2013-11-21
上传用户：lo25643
This application note shows how to achieve low-cost, efficient serial configuration for Spartan FPGA designs. The approachrecommended here takes advantage of unused resources in a design, thereby reducing the cost, part count, memory size,and board space associated with the serial configuration circuitry. As a result, neither processor nor PROM needs to be fullydedicated to performing Spartan configuration.In particular, information is provided on how the idle processing time of an on-board controller can be used to loadconfiguration data from an off-board source. As a result, it is possible to upgrade a Spartan design in the field by sending thebitstream over a network.
上传时间： 2013-11-01
上传用户：wojiaohs
MP3 portable players are the trend in music-listening technology. These players do not includeany mechanical movements, thereby making them ideal for listening to music during any type ofactivity. MP3 is a digital compression technique based on MPEG Layer 3 which stores music ina lot less space than current CD technology. Software is readily available to create MP3 filesfrom an existing CD, and the user can then download these files into a portable MP3 player tobe enjoyed in almost any environment.
上传时间： 2013-11-23
上传用户：nanxia
The Virtex-4 features, such as the programmable IDELAY and built-in FIFO support, simplifythe bridging of a high-speed, PCI-X core to large amounts of DDR-SDRAM memory. Onechallenge is meeting the PCI-X target initial latency specification. PCI-X Protocol Addendum tothe PCI Local Bus Specification Revision 2.0a ([Ref 6]) dictates that when a target signals adata transfer, "the target must do so within 16 clocks of the assertion of FRAME#." PCItermination transactions, such as Split Response/Complete, are commonly used to meet thelatency specifications. This method adds complexity to the design, as well as additional systemlatency. Another solution is to increase the ratio of the memory frequency to the PCI-X busfrequency. However, this solution increases the required power and clock resource usage.
上传时间： 2013-11-24
上传用户：18707733937
enter——选取或启动 esc——放弃或取消 f1——启动在线帮助窗口 tab——启动浮动图件的属性窗口 pgup——放大窗口显示比例 pgdn——缩小窗口显示比例 end——刷新屏幕 del——删除点取的元件（1个） ctrl+del——删除选取的元件（2个或2个以上） x+a——取消所有被选取图件的选取状态 x——将浮动图件左右翻转 y——将浮动图件上下翻转 space——将浮动图件旋转90度 crtl+ins——将选取图件复制到编辑区里 shift+ins——将剪贴板里的图件贴到编辑区里 shift+del——将选取图件剪切放入剪贴板里 alt+backspace——恢复前一次的操作 ctrl+backspace——取消前一次的恢复 crtl+g——跳转到指定的位置 crtl+f——寻找指定的文字
上传时间： 2013-11-01
上传用户：a296386173
The power of programmability gives industrial automation designers a highly efficient， cost-effective alternative to traditional motor control units （MCUs）。 The parallel-processing power， fast computational speeds， and connectivity versatility of Xilinx® FPGAs can accelerate the implementation of advanced motor control algorithms such as Field Oriented Control （FOC）。 Additionally， Xilinx devices lower costs with greater on-chip integration of system components and shorten latencies with high-performance digital signal processing （DSP） that can tackle compute-intensive functions such as PID Controller， Clark/Park transforms， and Space Vector PWM. The Xilinx Spartan®-6 FPGA Motor Control Development Kit gives designers an ideal starting point for evaluating time-saving， proven， motor-control reference designs. The kit also shortens the process of developing custom control capabilities， with integrated peripheral functions （Ethernet， PowerLink， and PCI® Express）， a motor-control FPGA mezzanine card （FMC） with built-in Texas Instruments motor drivers and high-precision Delta-Sigma modulators， and prototyping support for evaluating alternative front-end circuitry.
上传时间： 2013-10-28
上传用户：wujijunshi
