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Data transmitted may be digital messages originating from a data source, for example a computer or a keyboard. It may also be an analog signal such as a phone call or a video signal, digitized into a bit-stream for example using pulse-code modulation (PCM) or more advanced source coding (analog-to-digital conversion and data compression) schemes.
While the words analog audio usually imply that the sound is described using a continuous signal approach, and the words digital audio imply a discrete approach, there are methods of encoding audio that fall somewhere between the two. Indeed, all analog systems show discrete (quantized) behaviour at the microscopic scale. [52]
This technique uses digital encoding instead of analog signals used prior to the 1950s. [26] As compared to analog methods, DTV is faster and provides more capabilities and options for data to be transmitted and shared. [27] Digital television's roots are tied to the availability of inexpensive, high-performance computers.
A digital signal has two or more distinguishable waveforms, in this example, high voltage and low voltages, each of which can be mapped onto a digit. Characteristically, noise can be removed from digital signals provided it is not too extreme. Two main types of signals encountered in practice are analog and digital. The figure shows a digital ...
Earlier radio communication systems had to be made expressly for a given form of communications: telephone, telegraph, or television, for example. All kinds of digital communications can be multiplexed or encrypted at will. Digital cellular telephony (2G systems and later generations): GSM; UMTS (sometimes called W-CDMA) TETRA; IS-95 (cdmaOne)
Transmission of a digital message, or of a digitized analog signal, is known as data transmission. Examples of transmission are the sending of signals with limited duration, for example, a block or packet of data, a phone call, or an email.
Digital clock.The time shown by the digits on the face at any instant is digital data. The actual precise time is analog data. [1] Digital data, in information theory and information systems, is information represented as a string of discrete symbols, each of which can take on one of only a finite number of values from some alphabet, such as letters or digits.
Telephony and voice communication was originally primarily analog in nature, as was most television and radio transmission. Early telecommunication devices utilized analog-to-digital conversion devices called modulator/demodulators, or modems, to convert analog signals to digital signals and back.