Analogue signal VS Digital signal

January 9, 2016
Example digital circuit

Analog and digital signals are used to transmit information, usually through electric signals. In both these technologies, the information, such as any audio or video, is transformed into electric signals. The difference between analog and digital technologies is that in analog technology, information is translated into electric pulses of varying amplitude. In digital technology, translation of information is into binary format (zero or one) where each bit is representative of two distinct amplitudes.

Comparison chart

Analog versus Digital comparison chart Analog signal is a continuous signal which represents physical measurements. Digital signals are discrete time signals generated by digital modulation. Denoted by sine waves Denoted by square waves Uses discrete or discontinuous values to represent information Human voice in air, analog electronic devices. Computers, CDs, DVDs, and other digital electronic devices. Analog technology records waveforms as they are. Samples analog waveforms into a limited set of numbers and records them. Subjected to deterioration by noise during transmission and write/read cycle. Can be noise-immune without deterioration during transmission and write/read cycle. More likely to get affected reducing accuracy Less affected since noise response are analog in nature Analog hardware is not flexible. Digital hardware is flexible in implementation. Can be used in analog devices only. Best suited for audio and video transmission. Best suited for Computing and digital electronics. Thermometer PCs, PDAs Analog signal processing can be done in real time and consumes less bandwidth. There is no guarantee that digital signal processing can be done in real time and consumes more bandwidth to carry out the same information. Stored in the form of wave signal Stored in the form of binary bit Analog instrument draws large power Digital instrument drawS only negligible power Low cost and portable Cost is high and not easily portable Low High order of 100 megaohm Analog instruments usually have a scale which is cramped at lower end and give considerable observational errors. Digital instruments are free from observational errors like parallax and approximation errors.
Analog Digital
Data transmissions
Response to Noise

Definitions of Analog vs. Digital signals

An Analog signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are meaningful.

A digital signal uses discrete (discontinuous) values. By contrast, non-digital (or analog) systems use a continuous range of values to represent information. Although digital representations are discrete, the information represented can be either discrete, such as numbers or letters, or continuous, such as sounds, images, and other measurements of continuous systems.

Properties of Digital vs Analog signals

Digital information has certain properties that distinguish it from analog communication methods. These include

  • Synchronization – digital communication uses specific synchronization sequences for determining synchronization.
  • Language – digital communications requires a language which should be possessed by both sender and receiver and should specify meaning of symbol sequences.
  • Errors – disturbances in analog communication causes errors in actual intended communication but disturbances in digital communication does not cause errors enabling error free communication. Errors should be able to substitute, insert or delete symbols to be expressed.
  • Copying – analog communication copies are quality wise not as good as their originals while due to error free digital communication, copies can be made indefinitely.
  • Granularity – for a continuously variable analog value to be represented in digital form there occur quantization error which is difference in actual analog value and digital representation and this property of digital communication is known as granularity.

Differences in Usage in Equipment

Many devices come with built in translation facilities from analog to digital. Microphones and speaker are perfect examples of analog devices. Analog technology is cheaper but there is a limitation of size of data that can be transmitted at a given time.

Digital technology has revolutionized the way most of the equipments work. Data is converted into binary code and then reassembled back into original form at reception point. Since these can be easily manipulated, it offers a wider range of options. Digital equipment is more expensive than analog equipment.

Comparison of Analog vs Digital Quality

Digital devices translate and reassemble data and in the process are more prone to loss of quality as compared to analog devices. Computer advancement has enabled use of error detection and error correction techniques to remove disturbances artificially from digital signals and improve quality.

Differences in Applications

Digital technology has been most efficient in cellular phone industry. Analog phones have become redundant even though sound clarity and quality was good.

Analog technology comprises of natural signals like human speech. With digital technology this human speech can be saved and stored in a computer. Thus digital technology opens up the horizon for endless possible uses.


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