外文参考资料和译文封面定稿.doc

毕 业 设 计（论 文）外 文 参 考 资 料 及 译 文 译文题目：Telephone exchanges the principle and development 　　　　　 电话交换机的原理以及发展 学生姓名： 毛远 学　　号： 0805110803 专　　业： 通信工程 所在学院： 信息技术学院 指导教师： 杨娟 职　　称： 讲师 2011年 12月 7日说明： 要求学生结合毕业设计（论文）课题参阅一篇以上的外文资料，并翻译至少一万印刷符（或译出3千汉字）以上的译文。译文原则上要求打印（如手写，一律用400字方格稿纸书写），连同学校提供的统一封面及英文原文装订，于毕业设计（论文）工作开始后2周内完成，作为成绩考核的一部分。 Telephone exchanges the principle and development From《Brief introduction of SPC exchanges》 Abstract the classification of telephone exchanges 1) telephone exchange control mode is divided into the following two categories as: 1. The wiring logic control 2. Storage program control 2) according to the purposes of SPC exchanges can be divided into: audio signals, long-distance and users switch; 3) in the air way can be divided by time and switches. 4) of SPC exchanges by information transfer mode can be divided into: analog switches and digital switches. Due to the air in the network program-controlled switch (or exchange network) in air separation unit for wiring (or intersection switch array), and in the words of the general transfer and way of the exchange of analog voice signal is, and habits called program-controlled analog switches, the switch to voice the module conversion (decoding), the user circuit is simple, and low cost, mainly used as a small capacity simulation users switch. At the general in words program-controlled switch part way to transmit and switching is analog voice signals, thus habits called digital program-controlled switch, along with the digital communication and pulse code modulation (PCM) technology to the rapid development and application of, the advanced countries in the world since the s with great passion to developing digital program-controlled switch, through h