The heart of the package is 'libcw'.  This is a library which, when built,
offers the following basic CW services to a caller program:

  o Morse code character translation tables, and lookup functions
  o Morse code low-level timing calculations
  o A 'sidetone' generation and queueing system, using either the system sound
    card, the console speaker, or both
  o Optional keying control for an external device, say a transmitter, or an
    oscillator
  o CW character and string send routines, tied in with the character lookup
  o CW receive routines, also tied in to the character lookup
  o Adaptive speed tracking of received CW
  o An iambic keyer, with both Curtis 8044 types A and B timing
  o Straight key emulation

WWW: http://unixcw.sourceforge.net/