What is the difference in the usefulness of upper-sideband and lower sideband transmission?

Answer 1

There's no difference in their usefulness, and no basis for any preference on

the part of the transmitting party. There's an advantage to the receiving party,

however, if he can coordinate with the transmitting party. The advantage of

having a choice is that you can choose whichever mode encounters less

interference, and you can switch 'on the fly' if the congestion/interference

environment changes.

Upper sideband may be somewhat more difficult to receive clearly. This isn't a

technical issue, though. It's just sometimes harder for the operator behind the

tuning knob to tune it clearly, and slightly-mistuned upper sideband is harder to

understand than slightly-mistuned lower sideband is, because the frequencies

in the voice are inverted relative to each other.