Complex Signal Modulation

• Ring modulation involves multiplying two signals together, resulting in a spectrum composed of the sum and difference frequencies of the two waveforms.

• If there are $p$ frequency components in one waveform and $q$ frequency components in a second waveform, as many as $2 p q$ components will be present in the spectrum of the waveform produced by multiplication of the two.

• By carefully selecting the relationship between carrier and modulating frequencies, interesting and rich spectra can be produced via a relatively inexpensive computational operation.