A formal model of asynchronous communication and its use in mechanically verifying a biphase mark protocol

We present a formal model of asynchronous communication between two digital hardware devices. The model takes the form of a function in the Boyer-Moore logic. The function transforms the signal stream generated by one processor into that consumed by an independently clocked processor, given the phases and rates of the two clocks and the communications delay. The model can be used quantitatively to derive concrete performance bounds on communications at ISO protocol level 1 (physical level). We use the model to show that an 18-bit/cell biphase mark protocol reliably sends messages of arbitrary length between two processors provided the ratio of the clock rates is within 5% of unity.     

Fast Frequency Offset Acquisition and Accurate Tracking in OFDM Systems

1　IntroductionOrthogonalFrequencyDivisionMultiplexing(OFDM )isaneffectivetransmissionschemetocombatmultipathfading[1～ 2 ,1 7] .Byinsertingaguardintervalbetweensymbolblockscalledcyclicprefix,theInter SymbolInterference (ISI)canbemitigated .OFDMisadoptedasthemodulationschemeforaDigitalAudioBroadcasting (DAB)sys tem[3] andAsymmetryDigitalSubscriberLoop(ADSL) [4] andisalso proposedastheterrestrialHDTVtransportinEurope[5] .OFDMsystemisverysensitivetocarrierfre quencyoffset.Manymet…     

Dynamical adaptive synchronization

The notions of dynamical synchronization and adaptive dynamical synchronization problems are introduced. The algorithm solving adaptive synchronization problem for a subclass of Lurie systems with exciting input is proposed. The performance and potentialities of proposed solutions are demonstrated by two examples related to formation control and self‐organization of swarm systems. Copyright © 2006 John Wiley & Sons, Ltd.     

混沌电路同步的研究

本文叙述对混沌电路实现同步控制的实验研究之初步结果。所用的电路为蔡氏电路和锁相环电路。这项研究工作在通信系统中有应用前景。     

一种基于DBF的双基地雷达系统的性能分析与实验研究

讨论了一种基于数字波束形成的脉冲追赶式双基地雷达系统的构成和基本工作原理．对该双基地雷达的性能进行了理论分析，并通过实验结果进行了验证。     

高码率DQPSK遥测信号解调方法研究

本文根据高码速率 DQPSK遥测信号的特点 ,介绍了一种通过数字瞬时测频来完成对高码速率 DQPSK信号解调的方法。该方法算法简单 ,处理速度快 ,误码率低 ,能够有效地抑制多普勒频率对解调的影响 ,便于数字信号处理芯片硬件实现。同时给出了解调的仿真结果     

A NOVEL VARIABLE-LENGTH CODE FOR ROBUST VIDEO CODING

A novel Variable-Length Code （VLC）, called Alternate VLC （AVLC）, is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol error propagation effect, but also correct symbol insertion errors and avoid symbol deletion errors, so the original sequence number of symbols can be kept correctly, which is very important in video communication.     

Joint Synchronization and Channel Estimation for OFDM Systems

1Introduction Orthogonal Frequency Division Multiplexing(OFDM) has become a popular technique for transmis-sion of signals over wireless channels . OFDMhas beenadoptedinseveral wireless standards such as Digital Au-dio Broadcasting ( DAB) , Digital Video Broadcasting(DVB-T) ,the IEEE 802 .11a[1]Local Area Network(LAN) standard and high performance LAN type 2(HIPERLAN/2)[2]standard. OFDMis also being pur-sued for Dedicated Short-Range Communications(DSRC) for road side to …     

二滩电厂双缸液压启闭机原理及故障分析

二滩电厂表孔采用弧形门,启闭形式为双缸液压启闭机.自投入运行以来,运行状况良好.汛期启闭方式已由原来的现地手动操作过渡到远方控制自动启闭.在闸门起落的过程中,由于工况的不同,两缸会出现不同步现象,因此设计中考虑了纠偏回路.本文简单介绍了二滩电厂表孔液压启闭机的原理和故障情况.     

基于FPGA的位同步信号提取

同步是通信系统中一个非常重要的实际问题。在同步通信系统中,同步系统性能的降低会导致通信系统性能的降低,甚至使通信系统不能正常工作。因此,同步是信息能够正确可靠地进行传输的前提。介绍一种基于FPGA的锁相环位同步提取技术的原理,并用VHDL语言编程实现,在QuartusⅡ下编译仿真通过,给出仿真波形图。经分析该设计稳定可靠,且能够完成要求。