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#3
April 15th 10, 11:11 AM
posted to rec.radio.amateur.moderated
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generating morse code
Fred McKenzie wrote:
In article , (David Griffith) wrote: Does anyone here done something like sending ASCII to a microcontroller which then emits morse code? I'm tinkering around with old telegraph sounders. David- I understand the old telegraph sounders made a clack-clack sound rather than a beep. They also used an earlier version of code than international Morse, where some characters had mini-spaces in addition to dots and dashes. Either way, the solution may be similar. Use the ASCII code as an address for locating the timing required for each character, stored in a look-up table. Use a basic timing subroutine. Call it once for a dot or a space. Call it three times for a dash. Before calling it, turn on the output keyer for Mark and off for Space. If you didn't have an existing sounder, you could generate another timing interval that would repeat at an audio rate for the amount of time the Mark signal would be on. 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. -- David Griffith --- Put my last name where it belongs |
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