ds1

2 definitions found

ds1 - Free On-line Dictionary of Computing (26 May 2007) :

  DS1
  
     <communications> A DS level and framing specification for
     synchronous digital streams, over circuits in the North
     American digital transmission hierarchy, at the T1
     transmission rate of 1,544,000 bits per second (baud).
  
     DS1 is commonly used to multiplex 24 DS0 channels.  Each DS0
     channel, originally a digitised voice-grade telephone signal,
     carries 8000 bytes per second (64,000 bits per second).  A DS1
     frame includes one byte from each of the 24 DS0 channels and
     adds one framing bit, making a total of 193 bits per frame
     at 8000 frames per second.  The result is 193*8000 = 1,544,000
     bits per second.
  
     In the original standard, the successive framing bits
     continuously repeated the 12-bit sequence 110111001000, and
     such a 12-frame unit is called a super-frame.  In voice
     telephony, errors are acceptable (early standards allowed as
     much as one frame in six to be missing entirely), so the least
     significant bit in two of the 24 streams was used for
     signaling between network equipments.  This is called
     robbed-bit signaling.
  
     To promote error-free transmission, an alternative called the
     extended super-frame (ESF) of 24 frames was developed.  In
     this standard, six of the 24 framing bits provide a six bit
     cyclic redundancy check (CRC-6), and six provide the actual
     framing.  The other 12 form a virtual circuit of 4000 bits per
     second for use by the transmission equipment, for call progress signals
      such as busy, idle and ringing.  DS1 signals
     using ESF equipment are nearly error-free, because the CRC
     detects errors and allows automatic re-routing of connections.
  
     Compare T-carrier systems.
  
     [Kenneth Sherman, "Data Communications : a user's guide",
     third edition (1990), Reston/Prentice-Hall/Simon & Schuster].
  
     (1996-03-30)
  

ds1 - V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006) :

  DS1
         Digital Signal level 1 (ISDN, T1), "DS-1"