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一、传输系统概况1.1传输系统现状在当今世界各国的通信系统(网)中,模拟传输系统构成的模拟通信方式仍占绝对优势。但是,从六十年代中期开始,人们对数字通信日益重视。七十年代以来,通信领域的主要进展都是在数字通信方面。传输系统方面的进展主要反映在两个方面:一是研制新型数字调解器,把现有模拟传输系统改造成数字传输系统或模拟与数字混合传输系统;另一方面是研
I. Overview of Transmission System 1.1 Transmission System Status In the communication systems (networks) of all countries in the world today, the analog communication system composed of analog transmission systems still takes an absolute advantage. However, since the mid-1960s, there has been increasing emphasis on digital communications. Since the 1970s, major advances in communications have been made in digital communications. The progress of the transmission system mainly reflected in two aspects: First, the development of new digital demodulator, the existing analog transmission system into a digital transmission system or analog and digital hybrid transmission system; the other hand, research