Sounds to me like the old question as to whether or not a tree falling in a forest makes a crashing sound if there is no one around to hear it. In answering such a question one has to draw a distinction as to whether "sound" exists only as the reaction of the human auditory system to pressure waves in the conducting medium (air in this case) or, do these pressure waves themselves constitute "sound." Don seems to be saying sidebands exist only exist as a "physical reality" when apprehended by a human observer through the reactions of some kind of instrumentation (narrow receiver, etc.). Seems like a philosophical rather than an engineering issue to me.
Dennis D. W7QHO Glendale, CA
