CCWN 75:26
                                                      
        A conventional non-coherent CW signal will begin or end
at  random times; no matter how expertly the manually actuated
key or  electronic keyer is manipulated, the signal will exhibit,
to a  degree, randomness in element lengths and initiation
timings.          Other than the two factors cited above, a CCW
signal is generated  just as a conventional CW signal. In fact,
the techniques to achieve the  more stringent technical
requirements of CCW on selected frequencies  throughout the HF
amateur bands are not difficult. An additional bonus,  which was
not present during the conversion from AM to SSB equipment, is 
that a CCW signal is 100% compatible with conventional,
non-coherent receivers.   The CCW Receiver: The CCW receiver is a
conventional CW receiver that  has been frequency stabilized,
with a CCW Filter connected to the audio  output of the receiver.
At the CCW receiver, an extremely stable and  narrow digitally
controlled filter integrates the signal over each timing  period,
and reconstructs the original transmitted information. The output 
is a series of audio tones which can be read by ear or passed on
to a  Morse to RTTY convertor   The narrow receive bandwidth of
the filter and the synchronous  processing of morse information
at both the transmitter and distant  receiver will enable CCW
equipped stations to operate within 100 Hz of  each other without
adjacent channel interference. As W7GHM pointed out  in a more
technical analysis of CCW concepts and equipment (CCWN 75:7 ) 
using these techniques can result in a 20DB improvement in the
received  signal to noise ratio compared to an ordinary CW
receiver system.      CCW Station Requirements: A CCW Station
requires the following  elements:   (a) A frequency standard that
can maintain the accuracy and  stability required.      (b) An
electronic keyer that can generate time disciplined Morse in 
synchronization with a timing signal derived from the frequency
standard.      (c) A transmitter and receiver that can maintain
the frequency  stability required to hold the signal within the
band pass of the  coherent filter.      (d) The coherent filter
itself, that will generate the  reconstructed Morse signal from
audio information at the output of  the receiver.      (e)
Isolation and coupling devices to enable the components to 
function as a system.   The CCW Station: In recent months there
have been a number of  construction articles on items of
equipment that can easily be  adapted to CCW station components.