There are more stations seeking permission to transmit than there are frequencies available. Within a band of say, 100kHz, we can transmit only 5 signals that occupy 20kHz, but 10 stations if they agree to limit their transmitted bandwidth to 10kHz. It is for this reason that we limit the highest frequency component within the information wave. High quality music transmissions on the medium waveband are therefore not allowed. If so much of the transmitted wave is not required, then why transmit it? We will now look at of the alternatives.