The modulation process

The modulation process

As discussed earlier, the purpose of a communication system or to deliver a message signal from an information source in recognizable form to a user destination, with the source and the user being physically separated from each other.

To do this the transmitter modified the message signal into a form which is suitable for transmission over channel. This modification is achieved by means of a process as modulation, which involves varying some perameter of a carrier wave in accordance with the message signal. Also the receiver recreate the original message signal from a degraded version of the transmitted signal after propagation through the channel. The recreation is achieved by using a process called as demodulation.

Modulation may be defined as the process by which some characteristic of a signal called carrier is varied in accordance with the instantaneous value of another signal called modulation signal.

Signal containing information or intelligence are referred as modulation signal. This information bearing signal is also called baseband signal. The carrier frequency is greater them the modulation frequency. The signal resulting  from the process of modulation is called modulation signal.