Browse Definitions:

digital signal X

Contributor(s): Martin Gee, Patrick Tierce, and Michael Whyte

Digital signal X is a term for the series of standard digital transmission rates or levels based on DS0, a transmission rate of 64 kilobits per second (Kbps), the bandwidth normally used for one telephone voice channel. Both the North American T-carrier system and the European E-carrier system of transmission operate using the DS series as a base multiple. The digital signal is what is carried inside the carrier system.

DS0 is the base for the digital signal X series. DS1, used as the signal in the T1 carrier, is 24 DS0 (64 Kbps) signals transmitted using pulse-code modulation (PCM) and time-division multiplexing (TDM). DS2 is four DS1 signals multiplexed together to produce a rate of 6.312 Mbps. DS3, the signal in the T3 carrier, carries a multiple of 28 DS1 signals or 672 DS0s or 44.736 Mbps.

Digital signal X is based on the ANSI T1.107 guidelines. The ITU-TS guidelines differ somewhat. The following table summarizes the set of signals and relates them to the T-carrier and E-carrier systems.

Digital Signal Designator Data Rate DS0 Multiple T-Carrier E-Carrier
DS0 64 Kbps 1 - -
DS1 1.544 Mbps 24 T1 -
- 2.048 Mbps 32 - E1
DS1C 3.152 Mbps 48 - -
DS2 6.312 Mbps 96 T2 -
- 8.448 Mbps 128 - E2
- 34.368 Mbps 512 - E3
DS3 44.736 Mbps 672 T3 -
- 139.264 Mbps 2048 - E4
DS4/NA 139.264 Mbps 2176 - -
DS4 274.176 Mbps 4032 - -
- 565.148 Mbps 4 E4 channels - E5
This was last updated in September 2005

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