Before we can send a message signal over the communication channel, we need to modify the message signal into a form that is suitable for transmission over a channel. We called this process of modifying message signal as modulation. This modulation process involves changing some parameters of a carrier wave in accordance with the message signal so the resultant wave will match the communication channel's bandwidth. In order to recover the message signal, the receiver of the communication system will have to go through the demodulation process, which is the inverse of the modulation process.