【作者】 易成刚；

【导师】 陈伟；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 数字电视地面广播(DTTB)是近年来国际上大学和企业研究的热点之一,数字电视的地面广播基本代表了宽带数字通信的发展前沿,其特有的产值潜力引起了业界最大程度的关注。当前,世界上已有三种地面数字电视广播传输标准:①采用8VSB调制的美国高级系统委员会ATSC标准;②采用编码正交频分复用(COFDM)的欧洲数字视频广播组织DVB-T标准;③采用频带分段传输正交频分复用(BST-OFDM)的日本ISDB-T标准。而整合了ADTBT单载波标准和DMBT多载波标准的我国地面数字电视标准也于2006年正式公布,因此研究符合本国标准的地面传输接收技术有着深远的意义。DTTB所面临的困难主要是在无线广播信道中强烈的多径扩散会引起严重的信号衰落,尤其是在移动接收环境中信道的快速时变特性使得信号的恢复更加困难。如何消除多径干扰是地面数字电视接收机设计的重点和难点。对于单载波系统来说,一般采用时域均衡的方式消除多径干扰。本论文就是针对于国标ADTB-T接收系统提出一种高性能低复杂度的时域均衡器的实现方案。论文首先介绍中国地面数字电视标准,给出地面数字电视国家标准接收系统设计结构框图,然后对地面数字电视无线信道模型进行讨论,接着从时域均衡基本原理,均衡器基本结构以及均衡算法等方面对时域均衡器理论进行分析,最后讨论本设计采用的均衡器设计方案:本设计在结构上采用分数间隔的判决反馈均衡方式,减小了均衡器对定时误差的敏感度。在均衡算法上采用CMA+LMS的混合均衡算法,实现了快速稳定的均衡性能,并且为了减小均衡器硬件电路的开销,权衡静态信道和动态信道性能以及减小突发错误出现概率,本设计还采用了降低复杂度算法,步长控制算法以及减小误差扩散算法等优化算法。本文所提及的设计方案,在国标ADTB-T仿真平台上进行全面的仿真,从测试结果来看,本方案无论是对于静态信道还是动态信道都能获得了良好的性能,满足国标ADTBT接收系统的性能要求。更多还原

【Abstract】 Digital Television Terrestrial Broadcasting (DTTB) is one of hotspots researched by universities and enterprises around the world recently. DTTB basically represents the developing precursor of broad band digital communication. Its potential of product value arouses the most care among the industry. At present, there are three DTTB standards: (1)ATSC standard, which adopts 8VSB modulation.(2) DVB-T sdandard,which adopts OFDM technology.(3)ISDB-T standard,which adopts BST-OFDM tehchnology. National DTTB standard, composed of single carrier ADTB-T standard and multi carrier DMBT standard has been released in 2006. Research on terrestrial transmission technique according to digital television standard of our country has far-reaching meaning.DTTB has the stumbling block of serious signal fading, which is caused by high multi-path pervasion in wireless broadcasting channel. Especially, it is more difficult to recovery signals in moving receiver environment, due to the fast time variable characteristic of the channel. So towards Dibital Television Terrestrial Broadcasting receiving system, how to deal with Inter-symbol Interference is a keystone and difficulty. For single carrier system, we always adopt timing equalizer to eliminate Inter-symbol Interference. A low complexity fractionally spaced equalizer is presented based on National DTTB Standard ADTB-T in this paper. At the beginning of this paper, National DTTB standard is introduced, and receiving system structure of National DTTB standard is given. Then paper discusses wireless channel model of DTTB system, and analyses equalizer theory in several aspaces, such as: equalization basic principium, structure sort of equalizer and self-adaptive algorithm of equalizer. At last, this paper discusses the design project of equalizer adopted in ADTB-T receiving system: a fractional spaced decision feedback equalizer structure is adopted to minish sensitivity of equalizer to time error. For algorithm of equalizer, a CMA+LMS omnibus algorithm with effective switching control make the equalizer have high convergent speed and well basic performance, at the same time, in order to optimize performance of equalizer, a series algorithm such as: Low complexity algorithm, step size control algorithm, Mitigating Error Propagation algorithm and so on, is presented this paper.According to the simulation results based on ADTB-T platform, this design has well performance towards not only for static channels but also for dymatic channels, and makes the performance damand of national ADTB-T standard’s receiving system.更多还原