[CW] Re: CW in Emergency HF Comms System...

[David J. Ring Jr - N1EA]

Alan and George both sent in excellent emails.

CW should have built in error correction with a good operator - s/he knows
when there is phase distortion - or QSB, QRN, QRM that prevents copy - but I
will tell you that there have been times I didn't hear a dot when an audio
recording showed it was there, but also I have gotten a letter correct when
the audio recording had to be filtered and noise reduced about 15 times
before the code was detected by machine.

I remember during an SOS when I had 350 people onboard my ship, the U.S.
Coast Guard wanted us to send a message detailing each person's medical
prescriptions!

Quite a feat for a two man radio department - and NO purser!  Imagine
getting all those people organized for this?

I changed what the USCG wanted - they were (by that time) used to RTTY
communications.

I put over the loud hailer that anyone who needed prescriptions was to come
to a certain location at a certain time.

I then sent the list of about five prescriptions to the USCG via morse.

A big list could be sent by RTTY and it wouldn't take all that long - maybe
an hour or so - but to produce it would mean that someone would have to take
names of everyone.

That is one difference between CW messages and RTTY messages.

RTTY messages tend to be very nice, but often not needed.  CW messages by
necessity carry just the information needed to act on.

I remember COMSAT in its fight to get rid of the CW on ships was fond of
saying:

Morse can only communicate at 16 wpm during a distress - which is too slow.

We were "restricted" to send the SOS message between 13 and 16 wpm so that
the third class CW operators (who took a 16 wpm test) could copy this.  This
was a left-over from WW2 when we had 3rd class operators on ships.

During many SOS distresses traffic was handled at 25 to 35 wpm after the
initial CQ message with the SOS.

73

DR
----- Original Message ----- 
From: "Alan W." <n5lf@qsl.net>
To: <cw@mailman.qth.net>
Sent: Sunday, June 22, 2003 12:10 AM
Subject: [CW] Re: CW in Emergency HF Comms System...


> kburrows (VE1DS) wrote: "...the newer digital modes would be better than
> manual CW ..." [in an EOC].
>
> Well, CW & other digital modes are complementary; not interchangeable -
it's
> apples & oranges.
>
> CW is well-suited for for short messages, and low levels of formal
traffic,
> logistical communications, etc.  In other words the same situations where
a
> voice net is used on HF.  That is its most common use on ham radio in
> real-life emergencies -- CW supplements the limitations of SSB when
> conditions are poor.  So, two stations on a traffic or tactical/logistics
HF
> net can switch to CW if the receiving station was having trouble copying.
> It works every time!
>
> PSK31, on the other hand - and other new digital modes - are the only way
to
> go if you have to send a long list, or books of messages.  The originating
> station must type it in - not much faster than CW, and due to typos it can
> be LESS accurate.  But you see the big speed difference only when stations
> relay the traffic - since that is mostly automated.  If there are no
relays,
> then station to station speed isn't much different.  By the way, PSK31 is
50
> wpm - again, not much faster than a fast CW op, but 2x or 3x faster than
> most causal CW ops.
>
> There are conditions where CW shines - CW has full break-in operation for
> example - even between characters or even between dits.  SSB is only
between
> words at best, and PSK31 - hasn't got break-in capability.  In AMTOR &
> PacTOR the rcvr stn can break-in between packets, so they do to some
extent.
>
> PSK31 falls apart with multipath, auroral flutter, and other condx that
> affect a signal's phase.  Other modes handle phase shifts, but in exchange
> for other weaknesses.  CW ops can use the wetware between their ears to
> overcome this.
>
> The difference in equipment and power required to run a CW station vs. a
> soundcard-digital system has been expounded elsewhere.
>
> Bottom line:  On HF nets, CW supplements SSB.  CW has its own strengths &
> weaknesses (mainly requiring that we have CW ops!).  PSK31 & other new
digi
> modes are complementary to SSB & CW - not an "either-or".
>
> AlanW N5LF
>
>
>
> _______________________________________________
> CW mailing list
> CW@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/cw
>