Digital Signal – Definition, Characteristics, and Applications

The digital signal is a type of signal that uses information values defined at discrete instants of time. Therefore, digital signals are also known as discrete-time signals. In this article, we will explore the definition, characteristics, disadvantages, and applications of digital signals.

What is a Digital Signal?

A type of signal which contains information defined at discrete or discontinuous instants of time is referred to as a digital signal. It is also termed a discrete-time signal or discontinuous-time signal.

In other words, a digital signal is one which represents information as a sequence of discrete values. Basically, a digital signal is nothing but a discrete representation of analog signals.

Representation of Digital Signals

A digital signal can take only two values, i.e. 0 and 1. Hence, they are also called binary signals. Where the value 0 represents the low voltage level and the value 1 represents a high voltage level.

The graphical representation of the digital signal is shown in the following figure.

It can be seen that a digital signal has well-defined logic levels at specific time instants.

Types of Digital Signals

Digital signals can be classified into the following two major types:

(1). Unipolar Digital Signals:

A type of digital signal in which the binary states 0 and 1 are used to either a positive voltage level or negative voltage level is called a unipolar digital signal.

For example, a digital signal in which 0 represents 0 V and 1 represents +5 V, then it is called a unipolar signal.

Similarly, if 0 represents 0 V and 1 represents -5 V, then it is a unipolar digital signal.

In short, when both binary states, i.e. 0 and 1 represent only one polarity of the voltage, then the given digital signal is called unipolar digital signal.

(2). Bipolar Digital Signals:

A bipolar digital signal is one that uses binary states 0 and 1 to represent both negative and positive voltage levels.

For example, in a given digital signal, when 0 represents a low voltage level (let -5 V) and 1 represents a high voltage level (let +5 V). Hence, in this signal, both binary states represent both positive and negative polarities of the voltage, such digital signals are called bipolar digital signals.

Characteristics of Digital Signals

The following are some important characteristics of digital signals:

• Digital signals have discretely defined definite values.
• Digital signals are easy to express using binary digits, i.e. bits.
• Digital signals have very high noise immunity, making them ideal for information transmission over communication channels.
• Digital signals allow for efficient and fast error detection and correction using automated tools.
• Digital signals are reliable for transmitting information over long distances.
• Digital signals can be processed using digital systems like computers.
• Digital signals can provide an extra layer of security through an encryption mechanism.

Disadvantages of Digital Signals

Apart from advantages, digital signals also have several disadvantages. Some key disadvantages of digital signals are listed as follows:

• Digital signals typically require higher bandwidth to transmit data at higher rates.
• Digital signals require expensive infrastructure for transmission.
• Digital signals involve some advanced transmission systems, making them slightly complex and costly.
• Digital signals may have inaccuracies due to analog-to-digital conversion.

Applications of Digital Signals

Digital signals are widely used in the following applications:

• Digital signals are used in telecommunication networks for information transmission.
• Digital signals are used in internet technology and mobile and satellite communication.
• Digital signals are also used in computer networks like LAN, WAN, WiFi, etc.
• Digital signals are widely in digital electronic systems such as microprocessors, microcontrollers, smartphones, digital computers, etc.
• Digital signals are also utilized for data storage in digital memory devices like USB drives, SSDs, etc.
• Digital signals are widely utilized in digital control systems and robotics.

Conclusion

In conclusion, digital signals are those that represent information in the form of definite values defined as certain discrete time instants. Digital signals are represented using binary digits, i.e. discrete voltage levels. Digital signals are crucial for various industries like telecommunication, internet technology, robotics, automation and control systems, etc.