Video Demodulator (Tuner)

A demodulator is most often used in a video distribution system when the output of some device, such as a cable box, is to be modulated for distribution throughout the home. A cable box is needed to descramble the premium channel(s). But the cable box output is RF channel three, which is not suitable for modulation (it is already modulated, but on the wrong channel.) A demodulator can be tuned to channel three, and it will convert the cable box's channel three output back to baseband video and line-level audio, which is suitable for use by a "real" modulator.