Darrell Bellerive wrote:
> What is meant by "the fundamental keying waveform"?
I've wondered that myself. CW is made up of two separate periodic
waveforms ... one is symmetric (the dits) and one is asymmetric (the
dahs) and they occur in a more or less random sequence. For a given
sending speed, each has a fundamental frequency: a dit is two elements
in length, one on and one off. A dah is four elements in length, three
on and one off. So, a string of dits is a square wave and the sidebands
arise from the infinite series of sine wave harmonics, starting with the
"dit rate" needed to construct a square wave. Likewise for a string of
dahs, although the dah asymmetry would require a different coefficients
in the infinite series of sine wave harmonics. I guess the dit and dah
rates are low enough that some of those close in harmonics fall in a
normal CW passband and we hear them. Of course, if we really do key
with square waves, everyone else gets to hear all the others :-)
Fred K6DGW
Auburn CA CM98lw
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
