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 chartAnalog versus Digital comparison chart
|SignalAnalog signal is a continuous signal which represents physical measurements. Digital signals are discrete time signals generated by digital modulation.|
|WavesDenoted by sine waves Denoted by square waves|
|RepresentationUses discrete or discontinuous values to represent information|
|ExampleHuman voice in air, analog electronic devices. Computers, CDs, DVDs, and other digital electronic devices.|
|TechnologyAnalog technology records waveforms as they are. Samples analog waveforms into a limited set of numbers and records them.|
|Data transmissionsSubjected to deterioration by noise during transmission and write/read cycle. Can be noise-immune without deterioration during transmission and write/read cycle.|
|Response to NoiseMore likely to get affected reducing accuracy Less affected since noise response are analog in nature|
|FlexibilityAnalog hardware is not flexible. Digital hardware is flexible in implementation.|
|UsesCan be used in analog devices only. Best suited for audio and video transmission. Best suited for Computing and digital electronics.|
|ApplicationsThermometer PCs, PDAs|
|BandwidthAnalog 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.|
|MemoryStored in the form of wave signal Stored in the form of binary bit|
|PowerAnalog instrument draws large power Digital instrument drawS only negligible power|
|CostLow cost and portable Cost is high and not easily portable|
|ImpedanceLow High order of 100 megaohm|
|ErrorsAnalog 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.|
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.