telecommunications device for the deaf

1 definition found

telecommunications device for the deaf - Free On-line Dictionary of Computing (26 May 2007) :

  Telecommunications Device for the Deaf
  TDD
  Telecommunication Display Device
  TTD
  
     <communications> (TDD) A terminal device used widely by deaf
     people for text communication over telephone lines.
  
     The acronym TDD is sometimes expanded as "Telecommunication
     Display Device" but is generally considered to be derived from
     "Telecommunications Device for the Deaf".  The deaf themselves
     do not usually use the term "TDD", but prefer simply "TTY"
     -- possibly the original term.  The ambiguity between this and
     the other meanings of "TTY" is generally not problematic.
     The acronym "TTD" is also common [Teletype for the deaf?].
  
     The standard most used by TDDs is reportedly a survivor of
     Baudot code.  It uses asynchronous transmission of 1400 Hz
     and 1600 Hz tones at 45.5 or 50 baud, with one start bit,
     5 data bits and 1.5 stop bits.  This is generally
     incompatible with standard modems.
  
     A typical TDD is a device about the size of a small laptop computer
      (resembling, in fact, a circa 1983 Radio Shack
     Model 100 computer) with a QWERTY keyboard, and small
     screen (often one line high, often made of an array of
     LEDs).  There is often a small printer for making
     transcripts of terminal sessions.  An acoustic coupler
     connects it to the telephone handset.
  
     With the falling cost of personal computers and the
     widespread use of Internet talk systems, there is now
     little reason to use this Stone Age technology.
  
     [Standards?  i18n?]
  
     (2006-10-08)