[mikethedruid]

After doing considerable searching and reading through both the books in my own engineering library and also searching on line, I FINALLY have a decent explanation as to how the sidebands on either side of the carrier are generated. The books all too often just say "This is so" and give some mathematical formula, but don't give any clear explanation as to the HOW these sidebands come about. There is a simple, one word explanation, HETERODYNE. It is the same principle used to generate the IF in a superheterodyne radio. Just as when you mix two RADIO frequencies, you produce image frequencies both above and below the tuned carrier frequency by the sum and difference of the local oscillator frequency; when you combine an AUDIO frequency with a carrier frequency, you produce image frequencies both above and below the carrier frequency by the sum and difference of the two frequencies. Since speech and music consist of MULTIPLE frequencies, each of these frequencies which mix with the carrier frequency produce images above and below the carrier. This multiplicity of images forms what are known as the upper and lower sidebands. If you just remember the word HETERODYNE, and what it means, then sidebands make sense.