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传输2700个话路或一个电视图象加上1200个话路的同轴电缆系统,在过去15年来已被用在长曳电缆网络的长途干线上.第一个用电子管工作的这种系统由西门子(Siemens) 介绍过,并在1976年由具有埋地增音机的晶体管化同轴电缆系统所替代.此后,在总长约达18000公里的所有网络区间都安装了这种增音机.现在已发展起来的第二代晶体管中间增音机,由于考虑了过去在生产和使用中集累起来的经验,因而在工艺方面前进了一步.在这种增音机里,每个放大器所需的远供电源和所产生的噪声功率都有所减少,而且体积、重量和元部件数也有很大的减少.
A coaxial cable system that transmits 2700 channels or a TV image plus 1,200 channels has been used for long haul cable networks over the past 15 years. The first system to operate with a tube consists of Siemens introduced it and was replaced by a transistorized coaxial cable system with buried booms in 1976. Since then, it has been installed in all network sections, totaling some 18,000 kilometers, now The second generation of transistor mid-range amplifiers, which have been developed, have taken a step forward in the process by taking into account the past accumulated experience in production and use where the required amplifier Both the power supply and the generated noise power are reduced, and the volume, weight and number of components are greatly reduced.