(Optical cable communication has a history of more than 20 years of use, and this history is also the development history of optical communication technology and the development history of optical fiber and cable. The development of fiber optic cables in my country can be divided into the following periods: comments on the availability of fiber optic cables; local telephone cables and pcm cables that replace inter-office trunks in cities; high-frequency symmetrical cables and coaxial cables that replace wired communication trunks. These two replacements should be said to have been realized; they are now replacing the main)
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