DS level

DS level

(communications)(Digital Signal or Data Service level)Originally an AT&T classification of transmitting one ormore voice conversations in one digital data stream. The bestknown DS levels are DS0 (a single conversation), DS1 (24conversations multiplexed), DS1C, DS2, and DS3.

By extension, the DS level can refer to the raw data ratenecessary for transmission:

DS0 64 Kb/sDS1 1.544 Mb/sDS1C 3.15 Mb/sDS2 6.31 Mb/sDS3 44.736 Mb/sDS4 274.1 Mb/s

(where K and M signify multiplication by 1000 and 1000000,rather than powers of two). In this sense it can be used tomeasure of data service rates classifying the user accessrates for various point-to-point WAN technologies orstandards (e.g. X.25, SMDS, ISDN, ATM, PDH).

Japan uses the US standards for DS0 through DS2 but JapaneseDS5 has roughly the circuit capacity of US DS4, while theEuropean standards are rather different (see E1). Inthe US all of the transmission rates are integral multiples of8000 bits per second but rates above DS1 are not necessarilyintegral multiples of 1,544 kb/s.