通信原理重点知识总结.doc

1、Building industry opens up new world of entrepreneurial struggle to build a three provinces of regional central cities-in the Communist x counties the six plenary session members and comrades: today, I was commissioned by the County party Committee Standing Committee, reports to the General Assembly

2、. Consideration of all members and alternates, and comrades attending advice. A, and this year yilai of work recalled this year yilai, in municipal of right led Xia, County solidarity led County people, to science development views for guide, to good activities for mainline, according to a city four

3、 modernizations three more of development thought, concentrated poly force, work hard, political, and economic, and culture, and social and party of construction are made has new progress, County rendering out wind fresh are, and career prosperity, and social settled, and people mind into of good si

4、tuation. (A) facilitating the construction of the project. Firmly establish the scratch project is economic, grasping development project is to hold philosophy, to extraordinary efforts to promoting the construction of key projects. Plot 108 key projects for the year, with a total investment of 29.3

5、 billion yuan, iron plate, Josh stone cement waste heat power generation and 13 projects completed, worship of 1.2 million tons of pellets, Hua Yu 80,000 sets of grandparent chicken farming, 47 projects under construction, completed investment of 3.95 billion yuan, annual plan of 69.3%. The first ha

6、lf of the Countys gross domestic product is expected to reached 8.5 billion yuan, and total revenue of 943 million Yuan. (B) structural adjustment achieved remarkable results. Actively transforming the pattern of economic development, industrial ecology, and agricultural modernization and industrial

7、ization of services. High x-County • Tin iron circular economy demonstration area, and further expand economic development zone Jing Dian recycle economy ecology industry Park, Park, circular economy and rapid economic development. Focus more on the dialectical relationship between development

8、 and environmental protection, energy saving and emission reduction projects play an important role. Vigorously developing agriculture, ecological agriculture, agriculture, modern agricultural clearing along the River Promenade begins to take shape. Key tourism projects is going well, WA Palace area

9、 was named top ten most influential cultural relics in Hebei province landscape. Develop new services, and services with new developments. (C) urban-rural integration process. Promoting three-year difference campaign, battle of two large demolition completed 32 days of 530,000 square meters, exceede

10、d the annual Task 7 months in advance. General big building jiangjun road, bridge and highway bridges, the green heart of the city and other urban construction projects, and focus on building new countryside and new housing model villages, urban and rural areas improve. Highway opened to traffic, Li

11、u Zhang, Qing LAN high-speed x-County section completed by the end of August. Urban and rural第一章绪论1、通信的目的：传递消息中所包含的信息。2、信息：是消息中包含的有效内容3、模拟信号信号的参量取值是连续（不可数、无穷多）的（抽样信号未量化仍为模拟信号）数字信号信号的参量取值是可数的有限的4、按照信道中传输的是模拟信号还是数字信号，相应地把通信系统分为模拟通信系统和数字通信系统；按照传输媒介、通信系统可分为有线通信系统和无线通信系统5、模拟消息 原始电信号（基带信号）；基带信号 已调制信号（带通信号

12、） 6、数字通信系统模型信源编码与译码目的：提高信息传输的有效性完成模/数转换 信道编码与译码目的：增强抗干扰能力，提高可靠性基本的数字调控方式有振幅键控（ASK）、频移键控(FSK)、绝对相移键控(PSK)、相对（差分）相移键控(DPSK)按同步的公用不同，分为载波同步、位同步、群（帧）同步、网同步7、数字通信的特点优点抗干扰能力强，且噪声不积累传输差错可控便于用现代数字信号处理技术对数字信息进行处理、变换、存储。（便于将来自不同信源的信号综合到一起传输）易于集成，使通信设备微型化，重量轻易于加密处理，且保密性好缺点：需要较大的传输带宽对同步要求高8、按信号复用方式分类：频分复用、时分复用、

13、码分复用 按信号特征分类：模拟通信系统和数字通信系统按传输媒介分类：有线通信系统和无线通信系统 频分复用是用频谱搬移的方法是不同信号占据不同的频率范围；时分复用是用脉冲调制的方法使不同的信号占据不同的时间区间；码分复用是用正交的脉冲序列分别携带不同的信号。9、单工、半双工和全双工通信单工通信：消息只能单方向传输的工作方式半双工通信：通信双方都能收发消息，但不能同时收发的工作方式全双工通信：通信双方可同时进行收发消息的工作方10、信息及其度量P（x）表示信息发生的概率，I表信息中所含的信息量上式中对数的底：若a = 2，信息量的单位称为比特(bit) ，可简记为b 若a = e，信息量的单位称为

14、奈特(nat)，若a = 10，信息量的单位称为哈特莱(Hartley) 。通常广泛使用的单位为比特，这时有【例1】 设一个二进制离散信源，以相等的概率发送数字“0”或“1”，则信源每个输出的信息含量为 在工程应用中，习惯把一个二进制码元称作1比特。若有M个等概率波形（P = 1/M），且每一个波形的出现是独立的，则传送M进制波形之一的信息量为若M是2的整幂次，即 M = 2k，则有当M = 4时，即4进制波形，I = 2比特，当M = 8时，即8进制波形，I = 3比特。【例2】对于非等概率情况设：一个离散信源是由M个符号组成的集合，其中每个符号xi (i = 1, 2, 3, , M)按一

15、定的概率P(xi)独立出现，即，且有 则x1 , x2, x3, xM 所包含的信息量分别为于是，每个符号所含平均信息量为由于H(x)同热力学中的熵形式相似，故称它为信息源的熵 【例3】 一离散信源由“0”，“1”，“2”，“3”四个符号组成，它们出现的概率分别为3/8，1/4，1/4，1/8，且每个符号的出现都是独立的。试求某消息30 的信息量。 【解】此消息中，“0”出现23次，“1”出现14次，“2”出现13次，“3”出现7次，共有57个符号，故该消息的信息量每个符号的算术平均信息量为若用熵的概念来计算：则该消息的信息量以上两种结果略有差别的原因在于，它们平均处理方法不同。前一种按算数平均的方法，结果可能存在误差。这种误差将随着消息序列中符号数的增加而减小。当消息序列较长时，用熵的概念计算更为方便。11、通信系统主要性能指标通信系统的主要性能指标：有效性和可靠性有效性：指传输一定信息量时所占用的信道资源（频带宽度和时间间隔），或者说是传输的“速度”问题。可靠性：指接收信息的准确程度，也就是传输的“质量”问题。12、模拟通信系统：有效性：可用有效传输频带来度量。可靠性：可用接收端 最终输出信噪比来度量。 13、数字通信系统有效性：用传输速率和频带利用率来衡量。 （1）码元传输速率RB：定义为单位时间（每秒）传送码元的数目，单位为波特（Baud），简记为B。式中T 码