/**
\page cw_keyer CW Keyer Interface

The CW keyer is specifically designed to work with a DTR/RTS keyline to 
emulate the closure of a CW key.  Several transceivers have this capability 
built in to the hardware.  Some expose a separate keying port (FT-991A) and 
some share the CAT serial port (IC-7300).  A simple DTR/RTS keying circuit 
can also provide the h/w interface.  This one provides galvanic isolation:

<center>
\image latex cw-keyer/DTR_keyer.png width=2.0in
\image html  cw-keyer/DTR_keyer.png
</center>


*/
