1.0 Foundational Concepts of Communication

1.1 Defining Communication and Signals

Communication, derived from the Latin word commnicre (“to share”), is the process of exchanging information between two or more individuals through means such as words, actions, or signs. It is a fundamental necessity for co-existence among living beings.

The information itself is conveyed via a signal, which can be defined as a source of energy that transmits information. In electronic communication systems, a signal is typically an electrical impulse or an electromagnetic wave that travels a distance to convey a message.

1.2 The Communication System

Any communication system is comprised of three essential parts:

• Sender: The entity that sends a message. This can be a person or a transmitting station.
• Channel: The medium through which the message signals travel to reach the destination.
• Receiver: The entity that receives the message, such as a person or a receiving station.

1.3 Signal Classification

Signals are primarily classified based on their characteristics. The main distinctions are between analog and digital signals, and periodic and aperiodic signals.

• Analog Signal: A continuous time-varying signal that represents a time-varying quantity. Its value changes continuously over time. Communication based on such signals is called Analog Communication.
• Digital Signal: A signal that is discrete or non-continuous in nature. It consists of individual, separate values, with binary signals (representing 1s and 0s) being the most common form. Communication based on digital signals is called Digital Communication.
• Periodic Signal: An analog or digital signal that repeats its pattern over a specific period of time. Its behavior is predictable and can be easily calculated.
• Aperiodic Signal: An analog or digital signal that does not repeat its pattern over time. The pattern is not repetitive and is difficult to assume or calculate.

In practice, signals used in communication are often analog in nature but may be converted to digital for transmission depending on the system requirements.