digital signal X

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 6.312Mbps. 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