digital carrier

1 definition found

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

  digital carrier
  
     <hardware, communications> A medium which can carry digital
     signals; broadly equivalent to the physical layer of the
     OSI seven layer model of networks.  Carriers can be
     described as baseband or broadband.  A baseband carrier
     can include direct current (DC), whereas broadband carriers
     are modulated by various methods into frequency bands which do
     not include DC.
  
     Sometimes a modem (modulator/demodulator) or codec
     (coder/decoder) combines several channels on one transmission
     path.  The combining of channels is called multiplexing, and
     their separation is called demultiplexing, independent of
     whether a modem or codec bank is used.  Modems can be
     associated with frequency division multiplexing (FDM) and
     codecs with time division multiplexing (TDM) though this
     grouping of concepts is somewhat arbitrary.
  
     If the medium of a carrier is copper telephone wire, the
     circuit may be called T1, T3, etc. as these designations
     originally described such.
  
     T1 carriers used a restored polar line coding scheme which
     allowed a baseband signal to be transported as broadband and
     restored to baseband at the receiver.  T1 is not used in this
     sense today, and indeed it is often confused with the DS1
     signal carried.
  
     (1996-03-31)