Digital Signal

A digital signal is a discrete signal used in electrical circuits and devices. Digital signal is represented using binary values (0s & 1s) indicating a LOW voltage (0) or a HIGH voltage (1). The signal is represented in square-wave frequencies when using a digital logic analyzer or oscilloscope.

Electrical devices such are digital audio, video or computer modules are using these type of signals. These systems are called digital systems, which indicates that the information is represented by using digits. In digital signals, a digit can be binary (either 0 or 1), and each of these two binary digits are called a bit. The meaning of each bit depends on the place where it is used, therefore, a bit can represent ‘TRUE’ or ‘FALSE’, or ‘YES’ & ‘NO’, and in digital electronics, these bit digits indicate a boolean representation of ‘HIGH’ and ‘LOW’, or may indicate a logic gate indicated by binary values of electrical volts.

This signal has two specific levels (HIGH & LOW), and it does not vary smoothly, meaning that data with digital LOW value (indicated by binary 0) can be transmitted continuously, and likewise, the data with digital HIGH value (indicated by binary 1) can also be transmitted continuously. The transmission of these LOW/HIGH data values is specified by the transmission rate (known as bitrate), which indicates the number of bits/data that is transferred within a specific frequency frame.

Digital signals are more reliable for long-distance transmission and storage. The digital signal only takes discrete values (ie. LOW/HIGH data in a binary form), as opposed to Analog Signal which can vary in a continuous manner.

Reference to Digital Signal (Wikipedia) page for more details and information.

The conversion between the Analog<~>Digital Signals is a technique used to convert Analog to Digital (ADC - Analog-to-Digital Converter), and vice-versa, Digital to Analog (DAC - Digital-to-Analog Converter) signals.