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words per minute confusion

Discussion in 'Radio and Communications' started by bhuvaneshnick, Jun 26, 2014.

  1. bhuvaneshnick

    bhuvaneshnick Member

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    Transatlantic cable in 1880's can transfer 8 words per minute(approx 5bps per second)

    I have seen this in video. In general does the the word have any specific bits or the bits of the word change accordingly
     
  2. JimB

    JimB Super Moderator Most Helpful Member

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    For messages sent in Morse code, a "word" is loosly defined as five characters.
    In Morse code, the length of each character is different. E is the shortest character " . " and J is the longest " . _ _ _ ", the number 0 (zero) is the longest number " _ _ _ _ _ "

    So in the case of the transatlantic cable, there is not a hard definition of a word, it just averages out over time.

    JimB
     
  3. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Each "word" was composed of the "dits" and "dahs" (Morse Code, a dash and a dot both being a "bit" apiece, but with a slightly different duration) needed to indicate one letter of the "word".

    For instance, "cow" would require 10 "bits" (dah dit dah dit, dah dah dah, dit dah dah) . "Cows" would require 3 additional "bits" (dit, dit, dit).

    Each word, depending on the letters used, would require a different code set and, therefore, a different "bit" set.

    <EDIT> Looks like JimB beat me to it. Once again my poor typing skills strike...
     
  4. dave

    Dave New Member

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  5. atferrari

    atferrari Well-Known Member

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    Let's say that you are more "transatlantic" that him... :p :p :p
     
    Last edited: Jun 29, 2014
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  6. nsaspook

    nsaspook Well-Known Member

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    We used 5 letter 'word' code groups for transmitting off-line encrypted messages. We were told at school 5 letter group were chosen because it easily fits the short term memory of most people while typing continuously, adds rhythmic beat to audio encoding methods and acts as a error detection method for transmission errors. (more or less characters per group)
    http://jproc.ca/crypto/kl7.html
     
  7. Mike - K8LH

    Mike - K8LH Well-Known Member

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    If communications was Morse code, this info describing Morse code speed may be relevant.

    Cheerful regards, Mike

    Code (text):

    ;
    ; Some general information about Morse Code Speed;
    ;
    ; <1> A Dash is three times longer than a Dot
    ; <2> A Dot space is used between Dashes and Dots within a character
    ; <3> A pause between characters is three Dots long
    ; <4> A pause between words is seven dots long
    ;
    ; The word 'Paris' was established as an international standard
    ; for calculating the speed of Morse in words-per-minute (wpm)
    ; and characters-per-minute (cpm)...  This works out to 50 dots
    ; (or dot times) per word and yields the following timing;
    ;
    ;  5-wpm ( 25-cpm) =  60 /  250 dots = 240-msec / dot
    ;  6-wpm ( 30-cpm) =  60 /  300 dots = 200-msec / dot
    ;  7-wpm ( 35-cpm) =  60 /  350 dots = 171-msec / dot
    ;  8-wpm ( 40-cpm) =  60 /  400 dots = 150-msec / dot
    ;  9-wpm ( 45-cpm) =  60 /  450 dots = 133-msec / dot
    ; 10-wpm ( 50-cpm) =  60 /  500 dots = 120-msec / dot
    ; 15-wpm ( 75-cpm) =  60 /  750 dots =  80-msec / dot
    ; 20-wpm (100-cpm) =  60 / 1000 dots =  60-msec / dot
    ; 25-wpm (125-cpm) =  60 / 1250 dots =  48-msec / dot
    ; 30-wpm (150-cpm) =  60 / 1500 dots =  40-msec / dot
    ; 35-wpm (175-cpm) =  60 / 1750 dots =  34-msec / dot
    ; 40-wpm (200-cpm) =  60 / 2000 dots =  30-msec / dot
    ; 50-wpm (250-cpm) =  60 / 2500 dots =  24-msec / dot
    ;
     
     
    Last edited: Jul 2, 2014
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  8. RCinFLA

    RCinFLA Well-Known Member

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    You are trying to fit an older time into the modern digital word.

    As was mentioned Morse code was sent is groups of five character regardless of actual word been transmitted because of encoding. All during world war II all telegraph operators did the five character groupings that fit the "encryption" scheme.

    When you went for a General or higher amateur license test the bursts were sent in groups of five with a gap in time between. At about 13 words per min or higher you have to get accustom to falling a bit behind in the five character groups. It taught you to subconsciously go with flow instead of concentrating on individual characters.

    I got up to about 45 words per minute which turned out to be my limit on the electric typewriter. When you reach that level of proficiency it just flows from your ears to your fingers without thinking about it. You could day dream on something else or think about what you plan for the next day, that is until someone puts in a seldom used punctuation character at which time it totally knocked you off stride.
     
    Last edited: Jul 2, 2014

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