A report on Data communication

Transfer and reception of data in the form of a digital bitstream or a digitized analog signal over a point-to-point or point-to-multipoint communication channel.

- Data communication

29 related topics with Alpha

Overall

Categorization for signal modulation based on data and carrier types

Modulation

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Process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted.

Process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted.

Categorization for signal modulation based on data and carrier types
A low-frequency message signal (top) may be carried by an AM or FM radio wave.
Waterfall plot of a 146.52 MHz radio carrier, with amplitude modulation by a 1,000 Hz sinusoid. Two strong sidebands at + and - 1 kHz from the carrier frequency are shown.
A carrier, frequency modulated by a 1,000 Hz sinusoid. The modulation index has been adjusted to around 2.4, so the carrier frequency has small amplitude. Several strong sidebands are apparent; in principle an infinite number are produced in FM but the higher-order sidebands are of negligible magnitude.
Schematic of 4 baud, 8 bit/s data link containing arbitrarily chosen values

Most textbooks would consider digital modulation schemes as a form of digital transmission, synonymous to data transmission; very few would consider it as analog transmission.

Earth station at the satellite communication facility in Raisting, Bavaria, Germany

Telecommunications

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Transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems.

Transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems.

Earth station at the satellite communication facility in Raisting, Bavaria, Germany
Visualization from the Opte Project of the various routes through a portion of the Internet
A replica of one of Chappe's semaphore towers
Optical fiber provides cheaper bandwidth for long-distance communication.
Digital television standards and their adoption worldwide
here
The OSI reference model

There are analog communication systems and digital communication systems.

A binary signal, also known as a logic signal, is a digital signal with two distinguishable levels

Digital signal

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Signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values.

Signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values.

A binary signal, also known as a logic signal, is a digital signal with two distinguishable levels
A received digital signal may be impaired by noise and distortions without necessarily affecting the digits
A five level PAM digital signal
In signal processing, a digital signal is an abstraction that is discrete in time and amplitude, meaning it only exists at certain time instants.
A frequency-shift keying (FSK) signal is alternating between two waveforms and allows passband transmission. It is considered a means of digital data transmission.
An AMI coded digital signal used in baseband transmission (line coding)
A logic signal waveform: (1) low level, (2) high level, (3) rising edge, and (4) falling edge.
Clocking digital signals through a clocked flip-flop

Digital signals are used in all digital electronics, notably computing equipment and data transmission.

In The Signal by William Powell Frith, a woman sends a signal by waving a white handkerchief.

Signal

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Function that conveys information about a phenomenon.

Function that conveys information about a phenomenon.

In The Signal by William Powell Frith, a woman sends a signal by waving a white handkerchief.
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.
A binary signal, also known as a logic signal, is a digital signal with two distinguishable levels
Discrete-time signal created from a continuous signal by sampling
Signal transmission using electronic signals

Engineering disciplines such as electrical engineering have advanced the design, study, and implementation of systems involving transmission, storage, and manipulation of information.

Comparison of spectrograms of audio in an uncompressed format and several lossy formats. The lossy spectrograms show bandlimiting of higher frequencies, a common technique associated with lossy audio compression.

Data compression

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Process of encoding information using fewer bits than the original representation.

Process of encoding information using fewer bits than the original representation.

Comparison of spectrograms of audio in an uncompressed format and several lossy formats. The lossy spectrograms show bandlimiting of higher frequencies, a common technique associated with lossy audio compression.
Solidyne 922: The world's first commercial audio bit compression sound card for PC, 1990
Processing stages of a typical video encoder

In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted.

A short classification of the error correction codes

Error correction code

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Error correction code, sometimes error correcting code, is used for controlling errors in data over unreliable or noisy communication channels.

Error correction code, sometimes error correcting code, is used for controlling errors in data over unreliable or noisy communication channels.

A short classification of the error correction codes
A short illustration of interleaving idea

In telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels.

A two-dimensional visualisation of the Hamming distance, a critical measure in coding theory.

Coding theory

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Study of the properties of codes and their respective fitness for specific applications.

Study of the properties of codes and their respective fitness for specific applications.

A two-dimensional visualisation of the Hamming distance, a critical measure in coding theory.

Codes are used for data compression, cryptography, error detection and correction, data transmission and data storage.

Digital radio

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Use of digital technology to transmit or receive across the radio spectrum.

Use of digital technology to transmit or receive across the radio spectrum.

Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services.

Automatic repeat request

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Automatic repeat request (ARQ), also known as automatic repeat query, is an error-control method for data transmission that uses acknowledgements (messages sent by the receiver indicating that it has correctly received a packet) and timeouts (specified periods of time allowed to elapse before an acknowledgment is to be received) to achieve reliable data transmission over an unreliable communication channel.

Unrestricted signal (upper diagram). Bandpass filter applied to signal (middle diagram). Resulting passband signal (bottom diagram). A(f) is the frequency function of the signal or filter in arbitrary units.

Passband

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Range of frequencies or wavelengths that can pass through a filter.

Range of frequencies or wavelengths that can pass through a filter.

Unrestricted signal (upper diagram). Bandpass filter applied to signal (middle diagram). Resulting passband signal (bottom diagram). A(f) is the frequency function of the signal or filter in arbitrary units.

There are two main categories of digital communication transmission methods: baseband and passband.