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 |
Contributor(s): Martin Gee, Patrick Tierce, and Michael Whyte
This was last updated in July 2000
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