Difference between revisions of "Data transmission"
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'''Data transmission''', '''digital transmission''', or '''digital communications''' is the physical transfer of [[data]] (a digital bit stream or a digitized analog signal) over a point-to-point or point-to-multipoint communication channel. | '''Data transmission''', '''digital transmission''', or '''digital communications''' is the physical transfer of [[data]] (a digital bit stream or a digitized analog signal) over a point-to-point or point-to-multipoint communication channel. | ||
| − | Examples of such channels | + | == Description == |
| + | |||
| + | Examples of such channels include: | ||
| + | |||
| + | * Copper wires | ||
| + | * Optical fibers | ||
| + | * Wireless communication channels | ||
| + | * Storage media | ||
| + | * Computer buses | ||
The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal. | The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal. | ||
| Line 13: | Line 21: | ||
According to the most common definition of digital signal, both baseband and passband signals representing bit-streams are considered as digital transmission, while an alternative definition only considers the baseband signal as digital, and passband transmission of digital data as a form of digital-to-analog conversion. | According to the most common definition of digital signal, both baseband and passband signals representing bit-streams are considered as digital transmission, while an alternative definition only considers the baseband signal as digital, and passband transmission of digital data as a form of digital-to-analog conversion. | ||
| − | 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.This source coding and decoding is carried out by codec equipment. | + | 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.This source coding and decoding is carried out by codec equipment. |
== See also == | == See also == | ||
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* [[Analog signal]] | * [[Analog signal]] | ||
* [[Bit]] | * [[Bit]] | ||
| + | * [[Communications protocol]] | ||
* [[Data]] | * [[Data]] | ||
| + | * [[Data (computing)]] | ||
* [[Digital signal]] | * [[Digital signal]] | ||
Revision as of 17:11, 2 September 2015
Data transmission, digital transmission, or digital communications is the physical transfer of data (a digital bit stream or a digitized analog signal) over a point-to-point or point-to-multipoint communication channel.
Description
Examples of such channels include:
- Copper wires
- Optical fibers
- Wireless communication channels
- Storage media
- Computer buses
The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal.
While analog transmission is the transfer of a continuously varying analog signal over an analog channel, digital communications is the transfer of discrete messages over a digital or an analog channel.
The messages are either represented by a sequence of pulses by means of a line code (baseband transmission), or by a limited set of continuously varying wave forms (passband transmission), using a digital modulation method.
The passband modulation and corresponding demodulation (also known as detection) is carried out by modem equipment.
According to the most common definition of digital signal, both baseband and passband signals representing bit-streams are considered as digital transmission, while an alternative definition only considers the baseband signal as digital, and passband transmission of digital data as a form of digital-to-analog conversion.
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.This source coding and decoding is carried out by codec equipment.
See also
External Links
- Data transmission @ Wikipedia
