CCWN
75:49
                                                          
RECEIVING ORDINARY CW BY A CCW FILTER?

         Many people have asked if ordinary CW can be received by
a CCW filter. The answer is no. What we get is a random series of
dots, 2/3rds dashes, dashes, etc. The reason is that the CCW
filter is taking .1 second samples of the signal strength,
converting these into a sum of the signal strength for that
period, and then converting this into an output signal for .1
second. Since ordinary CW is not in phase with these time
periods, the basic information is lost and it appears to be a
series of random signals to us, much like noise. We must monitor
ordinarY CW in the traditional way.           Transmitted CCW can
be received on an ordinary receiver with no noticeable
difference.  KEYERS FOR CCW           Quite a few persons have
written questions about keyers. Andy uses the WN2DFA keyer (HR
Magazine, 1974, June). I have found my Heath HD-10 satisfactory.
As far as I know, no one has yet converted an AccuKeyer (ARRL
Handbook) but it looks to me like it would work find with a
replacement of the clock. I expect to get one in the next few
months. The basic consideration in the keyer is that the clock
signal must be replaced by a signal from the station standard.
Woody  INFORMATION AND ENERGY           G3FHL writes, 11 I have
often though that the price to be paid for sending a bit of
information is measured in joules, i,e., energy. The commercial
communicators use high power and have a large quantity of traffic
to send. We amateurs have only limited power, but unlike the
commercials we may have (relatively) unlimited time. So all we
have to do is send slowly, integrate coherently over a longer
time, and we can exploit our low data-rate advantage.          
Geoff, well put. You might think of the traditional reception
methods as integrating over a time period about the length of a
half cycle of the desired audio frequency. A 1 KHz beat note
gives about .0005 seconds. The current CCW standard is
integration over the length of a dot, or .1 second---hence the
improvement. Woody  CCW VIA OSCAR           Ron, 6Y5SR, asks
about interest in CCW via OSCAR. I think there would be
significant problems because of the doppler effects. The initial
part of the filter would need to be wider than the Petit filter.
I suspect that a phase lock loop approach would be useful. A PLL
would require difficult compromises, it would have to be wide
enough to allow acquisition, yet slow enough to retain lock
between letters and words. Coherent keying could still be used
for some improvement, but the gain would be more like 4 or 5 dB,
much less than we are experiencing with on-off keying. Woody