2. Understanding Signals: The Language of Information
- Understanding Signals: The Language of Information
In communication systems, a signal is an electrical impulse or an electromagnetic wave which travels a distance to convey a message. Signals are the vehicles that carry information from the sender to the receiver. They are broadly classified into two main types: Analog and Digital.
The table below compares these two fundamental signal types.
| Analog Signal | Digital Signal |
| An Analog Signal is a continuous, time-varying signal that represents a quantity as it changes over time. | A Digital Signal is a signal which is discrete in nature, meaning it has individual, separate values. |
| Analogy: Imagine a tap filling a 100-liter tank over one hour. The amount of water in the tank increases continuously over that hour. A graph of the water level versus time would be a smooth, unbroken line, representing an analog process. | Analogy: Consider the attendance of 20 students in a classroom over a week. The attendance on Wednesday might be 20, while on Saturday it is 15. Each day has a distinct, separate value. These are discrete values, representing a digital signal. |
While signals carry our message, they can’t travel very far on their own without getting weaker or distorted. To solve this, engineers use a clever process called modulation.