I contend that we are synthesizing a double-sideband with carrier signal when we modulate amplitude by varying PA B+, or by other means.
You can draw a graph of the carrier, upper sideband and lower sideband sine waves (of course you must make the relative timing/phase correct), and add them together, and the resulting composite signal will be identical to the modulated signal we produce with our modulated stage. Therefore I conclude that they are the same; that the sidebands exist, and that the carrier is continuous, even though the composite signal may vary from 0 to 2x the carrier level. ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; <[email protected]> Sent: Sunday, January 16, 2005 4:12 PM Subject: Re: [AMRadio] Physical Reality of Sidebands > 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 > ______________________________________________________________ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] >
