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View File - University of Engineering and Technology, Taxila

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Within the CCITT structure exist a number <strong>of</strong> study groups that providethe work classification or specialization for developing the recommendations.The CCITT has 17 study groups:I. Definition <strong>and</strong> operational aspects <strong>of</strong> telegraph <strong>and</strong> userservices (telex, facsimile, videotex, etc.)II. Telephone operation <strong>and</strong> quality <strong>of</strong> serviceIII. General tariff principlesIV. Transmission maintenance <strong>of</strong> international lines, circuits, <strong>and</strong>chains <strong>of</strong> circuits; maintenance <strong>of</strong> automatic <strong>and</strong> semiautomaticnetworksV. Protection against dangers <strong>and</strong> disturbances <strong>of</strong> electromagneticoriginVI. Protection <strong>and</strong> specifications <strong>of</strong> cable sheaths <strong>and</strong> polesVII. Data communication networksVIII. Terminal equipment for services (telex, facsimile, videotex,etc.)IX. Telegraph networks <strong>and</strong> terminal equipmentX. Telegraph switchingXI. Telephone switching <strong>and</strong> signallingXII. Telephone transmission performance <strong>and</strong> local telephonenetworksXIV. This group has similar function as Group 8XV. Transmission systemXVI. Telephone circuitsXVII. Data transmission over the telephone networkXVIII. Digital networksThere are joint CCIR <strong>and</strong> CCITT study groups, namely the CMV <strong>and</strong> CMTT,responsible for vocabulary <strong>and</strong> transmission <strong>of</strong> sound broadcasting <strong>and</strong>television signals over long distances, respectively.The recommendations <strong>of</strong> Group XVIII in particular have paved theway for the st<strong>and</strong>ardization <strong>of</strong> interfaces for public data networks <strong>and</strong>protocols for international packet-switched data networks. Their work, withsome contributions from Groups I, II, <strong>and</strong> XVII, has provided significantbuilding blocks for integrated services digital networks (ISDN) <strong>and</strong> in turnintegrated services digital satellite networks (ISDSN). With our rapidlychanging technology, particularly in multimedia <strong>and</strong> digital baseb<strong>and</strong> processing,Group 4 <strong>of</strong> CCIR has become involved in order to st<strong>and</strong>ardize ISDSNservices.Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.

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