Definition of a Digital Signal
A digital signal is a physical signal that represents information as a sequence of discrete values, typically binary (0s and 1s). Unlike analog signals, which vary continuously over time, digital signals have a finite number of possible states. These states are usually represented by distinct voltage levels, where one level signifies a '0' (low state) and another signifies a '1' (high state).
Key Characteristics and Advantages
The primary characteristic of a digital signal is its discrete nature. This provides several advantages, including robustness against noise, as minor fluctuations do not alter the distinct digital states. Digital signals are also easier to process, store, and transmit without degradation, enabling complex operations like error correction and encryption. They form the fundamental basis of all modern computing and communication systems.
Practical Example: Digital Audio
Consider digital audio, such as music on a CD or an MP3 file. The continuous sound waves from an original recording (an analog signal) are converted into a stream of numerical values through a process called analog-to-digital conversion (ADC). Each number represents the amplitude of the sound wave at a specific moment. These discrete numbers, when converted back to an analog signal by a digital-to-analog converter (DAC), reconstruct the sound wave with high fidelity and minimal noise.
Applications in Technology
Digital signals are ubiquitous in contemporary technology. They are used in computers for all internal operations, memory storage, and network communication. Mobile phones transmit and receive digital signals, as do digital televisions, cameras, and nearly all internet-connected devices. Their ability to precisely encode, transmit, and recover information makes them indispensable for the accuracy and reliability required in today's digital world.