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随着通信技术的发展,数字交换机也从早期的集中式控制方式发展到现在普遍采用的全分散控制方式。 早期全分散控制方式的典型代表是S1240。它采用模块化技术,各模块与数字交换网络(DSN)相连,构成以DSN为中心的交换系统。各终端模块完成单一的终端电路功能或辅助控制功能。典型模块种类有:模拟用户模块(ASM)、数字中继模块(DTM)、服务电路模块(SCM)、信号音和时钟模块(CTM)、辅助控制模块(ACM),维护和外设模块(M&PM)等。一个典型的本局呼叫需涉及4种模块:ASM、ACM、SCM和CTM。 继S1240交换系统之后,国际上出现了几种新型的数字交换机,如美国的5ESS,意大利的UT系统等。近
With the development of communication technology, digital switches have also evolved from the centralized centralized control mode to the fully decentralized control mode nowadays. A typical example of early fully decentralized control is S1240. It uses modular technology, each module is connected to the digital switching network (DSN) to form a DSN-centric switching system. Each terminal module to complete a single terminal circuit functions or auxiliary control functions. Typical module types include Analog Subscriber Module (ASM), Digital Relay Module (DTM), Service Circuit Module (SCM), Tone and Clock Module (CTM), Auxiliary Control Module (ACM), Maintenance and Peripheral Modules )Wait. A typical local office call involves four types of modules: ASM, ACM, SCM and CTM. Following the S1240 switching system, several new digital switches appeared internationally, such as 5ESS in the United States and UT in Italy. near