4. Noise: The Unwanted Interference

In any communication system, Noise is an unwanted signal that interferes with the original message signal and corrupts its parameters. It is the static or disruption that gets mixed in with the information you are trying to send or receive.

Common, everyday examples of noise include:

• Hiss sound in radio receivers
• Buzz sound during telephone conversations
• Flicker in television receivers

Noise has two primary negative effects on a communication system: it limits the system’s effective operating range and harms the receiver’s sensitivity, making it harder to detect the intended signal. This unwanted interference comes from two main sources:

• External Noise: Originates from sources outside the system, such as atmospheric disturbances (like lightning) or industrial interference from nearby machinery.
• Internal Noise: Produced by the receiver’s own electronic components as they function.

Successfully receiving a message, therefore, is a process of detecting the intended modulated signal and separating it from the inevitable background noise.