At 07:48 PM 3/11/03 -0600, Mark Beckwith wrote:
>f it was K4BAM (also common), you'd hear the rest of the "M". If you
>didn't hear that, you'd know it was John.
That example makes an interesting point, too. On CW in QRN or QRM , the
structure of code characters often provides a lot of clues. Once you have
a number, you know that all the other characters will fit within a certain
framework. If you hear an initial dot, for example, followed by a static
crash and then the beginning of another character, your mind processes the
gap between the dot and the beginning of the next character. If it is a
5-dot gap, then you know the letter that was garbled by that static crash
has to be "I" (dot (heard) plus one-dot pause plus dot (unheard) plus 3-dot
pause, then begin next character). If it's an "A" then the gap has to be 7
dots long; if it's a "W", then 11. These are pretty big differences,
percentage-wise, particularly when dashes are involved.
I believe that experienced CW operators go through this process
unconsciously, processing partly-heard characters and narrowing the
possibilities, then applying a list of likely calls (either mental or
computer-based). Of course, this assumes that the other station's fist is
good and even in speed; it's the big reason why I do not believe it's ever
helpful, on the average, to change speed within a callsign (or for that
matter, inside a contest exchange, where there's any need actually to copy
the information transmitted).
73, Pete N4ZR
The World HF Contest Station Database was updated 23 Feb 03.
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