On Dec 25, 2:57*pm, joe wrote:
K1TTT wrote:

distance itself does not affect sidebands.

frequency dependent dispersion in the ionosphere can affect sidebands
and the mark/space tones of rtty differently over short periods
causing differential fading and distortion.

One could also consider selective fading.

that's just another name for it... i threw in the big words because
i'm sure that mr.b will look them up out of context and find all sorts
of hilarious ways to recombine them.