| 单词 | E-carrier (European carrier) |
| 释义 | E-carrier (European carrier) A hierarchy of standards for digital transmission, E-carrier is based on the original North American T-carrier digital carrier system, although the specifics are quite different with respect to signaling rates, framing conventions, line coding technique, and PCM companding technique (A-law rather than µ-law). In many respects E-carrier is a considerable improvement over T-carrier. For example, E-1 supports 30 DS-0 payload channels, compared with T1 at 24 channels, and the higher E-carrier levels build on that difference. E-carrier also supports non-intrusive signaling and control through two channels reserved for such purposes. As a result, E-carrier supports clear channel communications of a full 64 kbps per DS-0, compared to 56 kbps data with T-carrier. The DS-0 (Digital Signal level Zero) is the fundamental building block of E-carrier, as it is with T-carrier and J-carrier, the Japanese version.Through time division multiplexing (TDM), E-carrier interleaves DS-0 channels at various signaling rates to create the services that comprise the European digital hierarchy, as detailed in Table E-3. |
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