G.703(数字系列接口物理电气特性)VIP专享

INTERNATIONAL TELECOMMUNICATION UNION CCITT G.703 THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE GENERAL ASPECTS OF DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS PHYSICAL/ELECTRICAL CHARACTERISTICS OF HIERARCHICAL DIGITAL INTERFACES Recommendation G.703 Geneva, 1991 FOREW ORD The CCITT (the International Telegraph and Telephone Consultative Committee) is the permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation G.703 was prepared by Study Group XVIII and was approved under the Resolution No. 2 procedure on the 5th of April 1991. ___________________ CCITT NOTES 1) In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication Administration and a recognized private operating agency. 2) A list of abbreviations used in this Recommendation can be found in Annex C.  ITU 1991 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation G.703 1 Recommendation G.703 PHYSICAL/ELECTRICAL CHARACTERISTICS OF HIERARCHICAL DIGITAL INTERFACES (Geneva, 1972; further amended) The...