Topband: Keying waveform

[Richard Karlquist]

> to full power can be a problem. The ideal shape would be like a half sine
> wave starting on what we would equate to the negative peak (at


> An ideal shape would come from filtering the key's square wave by
> a lowpass
> filter with sharp cutoff and linear modulating the rig, and using linear
> amplifiers with long hang ALC or no ALC. That would cost about $0.50-$1.00
>
> 73, Tom W8JI

Just wanted to point out that filtering a square wave through a brick wall
low pass filter results in a pulse that has both preringing and postringing
in the time domain.  This has narrower bandwidth than the half sine wave
(usually called "raised cosine" in books).  Not sure about which is
easier to copy by ear; that's not determinable mathematically.

Reference:  search "sinc function" and "FFT"

Rick N6RK