码分多址通信系统、扩频通信外文翻译

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1、 中文 2800 字 毕业设计英文翻译 专 业 电子信息工程 班 级 2010 级 学生姓名 学 号 课 题 码分多址通信系统的建模、仿真和设计 初始化模块、基站接收模块 指导教师 2014 年 06 月 10 日 译文原文 1.1 The basic concept of spread-spectrum communication Spread spectrum communications basic characteristics, is used to transmit information to the signal bandwidth(W) is far greater than

2、 practical required minimum(effective) bandwidth ( F ),as the radio of processing gain PG . FWGP / As we well know,the ordinary AM,FM,or pulse code modulation,GP value in the area more than 10 times,collectively,the “narrow-band communication”,and spread-spectrum communication GP values as hundred o

3、r even thousands of times, can be called “broadband communication”. Due to the spread-spectrum signal,it is very low power transmitters,transmission space mostly drowned in the noise,it is difficult to intercepted by the other receiver ,only spreading codes with the same (or random PN code) receiver

4、, Gain can be dealt with ,and despreading resume the original signal. 1.2 The technology superiority of spread-spectrum communication. Strong anti-interference, bit error rate is low. As noted above, the spread spectrum communication system due to the expansion of the transmitter signal spectrum, th

5、e receiver despreading reduction signal produced spreading gain, thereby greatly enhancing its interference tolerance. Under the spreading gain, or even negative in the signal-to-noise ratio conditions, can also signal from the noise drowned out Extraction, in the current business communications sys

6、tems, spread spectrum communications systems, spread spectrum communication is only able to work in a negative signal-to-noise ratio under the conditions of communication . Anti-multi-path interference capability, increase the reliability of system. Spread-spectrum systems as used in the PN has a go

7、od correlation, correlation is very weak. Different paths to the transmission signal can easily be separated and may in time and re-alignment phase, formation of several superimposed signal power, thereby improving the systems performance to receive increased reliability of the system. Easy to use t

8、he same frequency, improving the wireless spectrum utilization. Wireless spectrum is very valuable,although long-wave microwave have to be exploited, and still can not meet the needs of community. To this end, countries around the world are designed spectrum management, users can only use the freque

9、ncy applications,rely on the channel to prevent the division between the channel interference. Due to the use of spread-spectrum communication related receive this high-tech,low signal output power(“a W,as a general-100mW),and will work in the channel noise and thermal noise in the background,easy t

10、o duplicate in the same area using the same frequency,can now all share the same narrow-band frequency communication resources. Spread-spectrum communication is digital communication,particularly for digital voice and data transmission with their own encryption, only in the same PN code communicatio

11、n between users, is good for hiding and confidential in nature, facilitating communication business. Easy to use spread-spectrum CDMA communications, voice compression and many other new technologies, more applicable to computer networks and digitization of voice,image information transmission. Comm

12、unication in the most digital circuits, equipment, highly integrated, easy installation, easy maintenance, but also very compact and reliable. The average failure rate no time was very long. 1.3 Spread spectrum communication system Spread spectrum communication,namely, spread spectrum communications

13、 (Spread spectrum communication), with fiber-optic communications,satellite communications,with access to the information age as the three major high-tech communications transmission. Spread spectrum communication is to send the information to be pseudo-random data is coded(Spread spectrum sequence: spread sequence) modulation, spread spectrum and then the realization of transmission； the