On May 11, 2009, at 5/11 9:42 AM, Kevin H. Phillips wrote:
> Assuming that most people participating (?)
> are using computers and MMTTY, or similar programs, one thing I
> noticed
> was lack of Carriage Return and Line Feed at the end of transmissions.
The omission is deliberate.
If you send a newline, the line will jump on a computer screen at the
other end, potentially just when the op is trying to click on an
exchange to log it, causing an "air ball."
> A friend of mine (former Navy radioman who used MMTTY to monitor the
> contest) commented on confusion about callsigns because of "garbage"
> printing on MMTTY if a space or "K" or Carriage Return was not used at
> the end of a transmission.
The usual recommendation is to instead append a space character rather
than a newline to the end of a contest exchange, so the trailing
characters (usually part of a call sign) is not immediately followed
by "line noise."
> I had to ask some stations to repeat their
> exchanges several times because of overprinting.
This is because some computer programs send a single CR character,
instead of a CR and LF pair when they want to advance a line. These
programs do not understand the difference between a carriage return,
where the platen carriage moves to the left, and a linefeed, where the
platen of the teletypewriter turns to advance the paper.
Without a line feed, a mechanical teletype will overprint of the
current line when a carriage return is received.
Most programs are written to consider the reception of a linefeed or a
carriage return or a CR-LF pair as a single newline "character," so
they don't notice the missing newlines which you notice on a
mechanical teletype. cocoaModem has a "Print Control Characters"
checkbox where non-printing Baudot characters such as CR, LF and BEL
are shown on the screen, and I do see a lot of stations that are
sending CR without the paired LF.
73
Chen, W7AY
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