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generating morse code
David Griffith wrote:
\ I have a couple vintage sounders. Hook a batter and key in serial with a sounder. When the key is down, the sounder clicks down. Let go and it clacks up. So, a dot is "click-clack" and a dash is "click-wait-clack". I think the Mark and Space stuff has to do with the fact that the line was always kept energized, thus, an idle line would hold the sounder arm down. That way you'd know immediately if there was a line fault. That would be a bit wasteful now, so I suppose I should preceed each message with a very long dash to at least try to fake that part. As I recall there is international Morse Code and American Morese code.. Two different codes, and one (American I think) is better suited to the click/clackers and guess what.. That font of much knowledge http://en.wikipedia.org/wiki/American_Morse_code Has an article on it at the above link INCLUDING the code itself!!!! Also called the Railroad code.. IT is not as suited to radio as International Morse code is. As to the line running energized.. There are several reasons for this, Many countries the phone system keeps current flowing in the wires all the time, this is called "Sealing Current" and if you have the manual for an old 300 or 1200 baud modem lying about you can read all about it. The reason for this is to PREVENT line faults, believe it or not. As well as instant detection of line faults. Modern teletype (BAUDOT and later ASCII teletype machines) like the Type 15, 28 and 33 all used idle on MARK One of the more interesting lengths of paper tape I used to have was punched by one of the national news wires one November back in what, 1963 (The 23th as I recall) You play the tape and it starts typing out routine items (I recall a farm report or some such but it's been many years since I played the tape) then suddenly the machine runs "OPEN" (Space) for a period and then the news flash.. Then it goes back to routine and again it runs open.. the operator intruppted sends "Go Ahead Dallas" and we read "The president is dead" That's some tape. |
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