catflap.org Online Dictionary Query

  DS level
       
           (Digital Signal or Data Service level)
          Originally an AT&T classification of transmitting one or
          more voice conversations in one digital data stream.  The best
          known DS levels are DS0 (a single conversation), DS1 (24
          conversations multiplexed), DS1C, DS2, and DS3.
       
          By extension, the DS level can refer to the raw data rate
          necessary for transmission:
       
           DS0      64 Kb/s
           DS1   1.544 Mb/s
           DS1C  3.15  Mb/s
           DS2   6.31  Mb/s
           DS3  44.736 Mb/s
           DS4 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 to
          measure of data service rates classifying the user access
          rates for various point-to-point WAN technologies or
          standards (e.g. X.25, SMDS, ISDN, ATM, PDH).
       
          Japan uses the US standards for DS0 through DS2 but Japanese
          DS5 has roughly the circuit capacity of US DS4, while the
          European standards are rather different (see E1).  In
          the US all of the transmission rates are integral multiples of
          8000 bits per second but rates above DS1 are not necessarily
          integral multiples of 1,544 kb/s.
       
          (1998-05-18)