[CW] Speed vs Bandwidth

[Gerry Maira]

Buck wrote:
> 
> For some unknown reason, I have been bugged lately about the theory I
> learned 25 years ago that the faster a cw signal is sent, the broader
> the bandwidth of the signal.  I didn't get my license by learning the
> questions and answers.  While I am not a CET or equivilent, I have
> studied electronics and had to get my license by learning theory.  (This
> isn't a put-down to those who used the q/a method, its my background so
> readers get a feel for my understanding of electronics).
> 
> When I studied it, I had no choice but to accept the theory that the
> signal width (band-width) is actually greater, the higher the speed of
> the cw.
> 
> In practice, I see that the more power I receive from a station, ie the
> greater the signal strength, the greater the tuning band-width that I
> can receive some noise of interference, as it may be.  However, in cw,
> whether its a carrier or someone sending 60+ wpm, at s-5 or so, I can't
> tell the difference between the width of either station.
> 
> Has anyone actually tested this theory on a spectrum analyzer?  Is this
> a theory we just have to accept or is there any real basis for the
> statement.  You folk might have to forgive me, but I can't immagine that
> there is actually a cw speed that could consume the entire 80 meter ham
> band.  I can imagine a cw speed that is so fast that on 80 meters it
> can't be copied reliably but, and maybe I understand it wrongly, I can't
> think of anything that will key on and off so fast that my rig will
> actually transmit two or three times the signal width in it's specs.
> 
> The world won't come to an end if I never understand this, but if
> someone can explain, I would appreciate it.
> 
> Thanks
> 
> Buck

There is no difference in bandwidth if the only thing changed is the speed of keying.
It's the same as SSB - Talking faster doesn't increase bandwidth.

73, Gerry KA2MGE