[Hallicrafters] Final word on 5 char. CW

[Waldo Magnuson]

CW and 5-character groups

   I received several comments on why CW used 5 character groups in 
WW-II.  The comments generally mentioned the following:
   1) People can retain a group of 5 characters but remembering errors 
increase with over 5 and using less than 5 is inefficient.
   2) CRIPTO machines were designed to encode, transmit, receive, and 
decode using groups of five.
   3) Using 5 character groups made it more difficult for the enemy to 
decode.
   4) And several other suggestions including 5 is just a convenient 
number to use.

   But I received the best and most likely correct account from a 
retired commercial maritime operator in New Zealand.  The background 
for using 5 character groups dates back to the 1890s and the increasing 
use of teletypes in businesses.  In 1903 the use of artificial words 
was authorized by an international conference in London.  Code 
companies published books with pronounceable 5-letter codes.  The 
reason for the code books was that telegraph companies charged by the 
word and words were defined as 5 characters.  By using 5 character 
codes, a complete sentence could be stated by one 5 letter group.  I 
think they needed to be pronounceable so the message could be dictated 
over a telephone or read to someone.  For example an airline pilot 
might wire VAOIK (meaning: forced landing account engine trouble) using 
the Avico Aviation Code.  The use of 5 character code groups was used 
in WW-I, and by business during the 1920s and 30s. In fact the Enigma 
machine was first patented in 1919 and adapted by the German Army and 
Navy in the late 1920s.  It used 5 letter groups and initially was used 
by businesses.  Some of the responses I received indicated 5 character 
groups were in use by the USAF in the 1950s and 60.

    Thanks for all of the input.  I now understand better a question 
that has bothered me for several years.

73,  Skip Magnuson  W7WGM
Spokane, WA