Modulation: Preparing Signals for Propagation

Modulation creates a radio or light signal from the network data so that it is suitable for propagation through the air. This involves converting the digital signal contained within the computer into an analog signal. As part of this process, modulation superimposes the information signal onto a carrier, which is a signal having a specific frequency. In effect, the information rides on top of the carrier. In order to represent the information, the modulation signal varies the carrier in a way that represents the information.

This is done because it's generally not practical to transmit the information signal in its native form. For example, consider Brian, who wants to transmit his voice wirelessly ...

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