| Journal Call no. | HE8421.C48 |
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| Author | Ren, Shunyao. |
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| Article Title | ITU-T's effort in research on recommendations relating to SDH and China's R&D in the field of SDH equipment / Ren Shunyao. |
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| Is Part Of | China telecommunications construction ; v.7, no.8, Nov 1995, p.23, +4p., illus. |
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| Abstract | Since the 1970's, plesiochronous digital hierarchy (PDH) systems have been playing an important role in digital transmission but with restriction. In view of the weaknesses, the United States began research into the optical transmission of synchronous signals in early 1984, aiming at realizing standardization over optical circuits, and the interworking of products by different manufacturers. This article traces the evolution from PHD to SDH. ITU-T's recommendations relating to SDH are also included, and the research and development on SDH equipment in China are depicted. |
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