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一、引言 1960年贝尔实验室开创了用计算机控制交换机的历史。1965年同时出现了两个代表性较强的实用系统:1号ESS交换系统和ⅢW6030交换系统。前者采用空分程控交换,后者则是时分交换的代表。70年代微处理机问世对电话交换技术的发展起了决定性的作用。程控交换机渗透率有了大幅度增长,但小型交换机所采用的技术大部分仍是机电式的。随着电子技术,特别是VLSI技术的发展,程控方式在造价上已呈现出优于布线逻辑控制的趋势,所以研制小型程控全电子交换机有着极大的意义。目前实现全电子交换主要有两种方式:一种是利用半导体矩阵替代空分交换机的金属接线器;另一种是借助于时分原理,采用复用公共通话线的方式实现语音交换。其中主要有PCM和PAM两种调制方法。
I. Introduction In 1960, Bell Labs pioneered the history of using computer controlled switches. In 1965, two representative practical systems emerged simultaneously: No. 1 ESS Switching System and ⅢW6030 Switching System. The former uses air separation program-controlled exchange, the latter is the representative of time-sharing. The advent of microprocessors in the 1970s played a decisive role in the development of telephone exchange technology. Program-controlled switch penetration has increased dramatically, but most of the technology used by small switches is still electromechanical. With the development of electronic technology, especially VLSI technology, the program-controlled method has shown a trend of cost-effective control over wiring logic. Therefore, it is of great significance to develop a small program-controlled full electronic switch. At present, there are mainly two ways to realize full electronic exchange: one is to use the semiconductor matrix to replace the metal switch of the air separation switch, and the other is to realize the voice exchange by means of the time division principle and the method of multiplexing the public call lines. One of the main PCM and PAM modulation methods.