SOS

The amateur distress call, QRRR, grew from the purpose of the first
organized amateur emergency nets. They were set up in cities along the Pennsylvania Railroad to aid the "Pennsy" (and later other railroads)
with train communications in the event of failure of the railroad
telegraph landlines--which were frequent. The signal QRR came to be used
to indicate that the calling station had railroad traffic related to
some emergency. ARRL eventually adopted this call for use by any amateur
who had distress traffic and later the call was changed to QRRR because
of a conflict in definitions with the international Q signal QRR.

One of the first distress calls was CQD, coined by the Marconi Company
about 1904 from the "general call" CQ and the letter D for "distress."
The main problem with CQD was that it was supposed to be used only by
ships which subscribed to the Marconi radio system and ships of one
system were discouraged from communicating with ships or shore stations
of other, competing, companies. The problem got so bad that it was taken
up in the international radio conference in 1906 where a new universal
distress call was proposed.

The American delegation suggested the letters NC which were already
recognized in the International Signal Code for Visual Signalling. The
German delegation proposed its own SOE which was already in use on German
ships as a general inquiry signal similar to CQ (which was then used only
by the Marconi system). The British delegation, of course, wanted to
stick to the Marconi signal CQD.

The convention found SOE acceptable except that the final E could easily
be lost in QRN so the letter S was substituted, making it SOS. The
convention decided that SOS should be sent as a single code character
with a sound unlike any other character, thus arresting the attention of
anyone hearing it. So was officially adopted, but CQD remained in use for
some years, particularly aboard British ships.

It wasn't until 1912, after the Titanic disaster, that SOS became the
universal choice, and the use of CQD gradually disappeared. Titanic radio operator Jack Phillips sent both CQD and SOS to be sure that there could
not possibly be any misunderstanding.

SOS does *NOT* stand for Save Our Ship or Save Our Souls.

***

Mayday

Incidentally, another distress call is used by aircraft in trouble
throughout the world. We have all heard the term "mayday" at some time.
This, of course, has nothing to do with the first day in May. As it
turns out, in French, the word "m'aidez" means "help me". Is it possible
that American aviators in World War I picked this up from their French comrades, and mispronounced it as the easily recognized "mayday, mayday"?

***

The Prosigns

Many of the expressions and procedure signals still in use in
radiotelegraph had their origins in the early days of the landline telegraph--long before Marconi sent his letter "S" across the Atlantic.

In sending formal messages by c.w., the first thing a beginner hears is
"don't send punctuation. Separate the parts of the address from each
other with the prosign AA." This is ironic, because in the American Morse
Code the sound didahdidah is a comma, and was doubtless the origin of our prosign. Originally, a correctly addressed letter was punctuated with
commas following the name and the street address, each of which was
(and still is) on a separate line although the commas have been dropped,
even in mail addresses on letters. The comma was transmitted by Morse
operators and thus, AA came to mean that the receiving operator should
"drop down one line" when sent after each part of the address, and it is
so defined in the operating manuals of the time.

Our familiar prosign SK also had its origin in landline Morse. In the
Western Union company's "92 code" used even before the American Civil
War, the number 30 meant "the end. No more." It also meant "good night."
It so happens that in Landline Morse, 30 is sent didididahdit daaah, the
zero being a long dash. Run the 30 together and it has the same sound as
SK.
--- SBBSecho 3.20-Win32
* Origin: The Thunderbolt BBS - Little Rock, Arkansas (954:895/7)