A signal is an electrical or electromagnetic quantity that transports data or information from one system to another. For data transmission, two types of signals are used: Analog signals and digital signals. 

Analog and digital signals are very different in many ways. An analog signal is a continuous function, whereas a digital signal is a discontinuous function. 

Typically speaking, analog and digital signals are two signal kinds that carry data or information. As far as analog signal vs digital signal is concerned, analog signals feature continuous electrical signals, whereas digital signals are otherwise without continuity in signals. 

Types of Signals 

Signals are classified into two types: 

Continuous-time signals/ Analog signals: A continuous-time signal is any continuous function of time. 

Discrete-time signals/ Digital Signals: A discrete-time signal is any series of real numbers separated by equal time increments (or samples). 

Analog signals are used to create information-carrying signals in a variety of systems. Both in terms of quantities and time, these signals are continuous. As technology evolved, digital transmissions repealed the use of analog signals. Signals that are natural or occur naturally are analog signals. Since it denotes a quantity that is analogous to another measure, it is called so. Analog signals are known for use of medium to channelize the flow of information. Analog signals can be easily distorted, thereby losing clarity and quality. 

Examples of Analog Signal 

Any natural sound, human voice, and data read by analog devices are examples of analog signals. 

Characteristics of analog signals 

Analog signals denote a voltage or any physical quantity that is continuous and invariable and fluctuates in its quantity based on the parameter whose behavior changes according to time. These can be radio waves, broadcast waves 

Further classification of analog signals based on characteristics: 

Continuous-time signals and discrete-time signals 

Analog signal processing makes use of the electronic devices to conduct several operations on the signals. These can be ranging from amplification to limiting. Certain tools used in processing analog signals are analog signal generators, power supply, oscilloscopes and certain other electronic equipment. 

Measuring analog signals 

For an analog signal source, its amplitude is measured in volts while the frequency of an analog signal is measured in Hertz. Thus, analog signals carry three categories of information – amplitude, frequency and phase 

What is Digital Signal? 

A digital signal is one that is a discrete function of time rather than a continuous signal. Digital signals are binary in nature and consist of discrete voltage values at discrete times. A digital signal, in essence, represents data and information as a sequence of discrete values at any given time. The digital signal has a limited number of values. 

Characteristics of digital signals 

The digital signal is a discrete delivery time and is a non-continuous signal. The bandwidth of digital signals is very high so, they are highly suitable for functions such as computing, digital operations, data storage, etc. The square wave function represents digital signals. These digital signals have fewer fluctuations, healthier instability, and do not fall prey to noise and disturbances, unlike analog signals. 

The accuracy and precision of digital signals is also high due to the zero effect of sound on them. They also use less power and give zero errors 

Difference between Analog Signals and Digital Signals 

The table below highlights all the key differences between Analog and digital transmissions. 

1. Nature of Signal: 

Analog Signals: Continuous signals that vary smoothly over time. They represent information by changing the amplitude, frequency, or phase of the signal in a continuous range. 

Digital Signals: Discrete signals that have distinct levels, usually represented by binary values (0s and 1s). These signals are non-continuous and switch between fixed levels. 

2. Representation: 

Analog Signals: Represented by sine waves or smooth curves. Examples include audio signals or temperature changes. 

Digital Signals: Represented by square waves or step functions, with distinct values like on/off or high/low. 

3. Transmission: 

Analog Signals: More prone to degradation and noise during transmission, as interference can affect the signal’s smooth waveform. 

Digital Signals: More resilient to noise and distortion. Digital signals are less affected by transmission errors because the values are either "high" or "low," making them easier to distinguish even with interference. 

4. Bandwidth: 

Analog Signals: Usually require more bandwidth for transmission due to the continuous nature of the signal. 

Digital Signals: Generally use less bandwidth compared to analog signals for transmitting the same amount of information. 

5. Signal Processing: 

Analog Signals: Require complex filtering techniques for signal enhancement and noise reduction. 

Digital Signals: Easier to process with algorithms and can be compressed, encrypted, or corrected using error detection methods. 

6. Example Uses: 

Analog Signals: Used in traditional telephones, radio broadcasting, and older TV systems. 

Digital Signals: Used in computers, modern telecommunication systems, digital TV, and data storage. 

7. Signal Accuracy: 

Analog Signals: More accurate in representing real-world phenomena since many physical quantities are naturally analog. 

Digital Signals: Less accurate in capturing fine details due to sampling, but the use of higher sampling rates in digital systems can mitigate this.