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Information about Synchronization

Synchrony redirects here. For the X-Files episode, see Synchrony (The X-Files).
For similarly named concepts, see synchronicity (disambiguation).
Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time. Systems operating with all their parts in synchrony are said to be synchronous or in sync. Some systems may be only approximately synchronized, or plesiochronous. For some applications relative offsets between events need to be determined, for others only the order of the event is important.

Today, synchronization can occur on a global basis due to GPS-enabled timekeeping systems.

Transport

Apart from its use for navigation (see John Harrison), synchronization was not important in transportation until the nineteenth century, when the coming of the railways made travel fast enough for the differences in local time between adjacent towns to be noticeable (see [1]).

In some territories, sharing of single railroad tracks was controlled by the timetable. Thus strict timekeeping was a safety requirement. To this day, railroads can communicate and signal along their tracks, independently of other systems for safety.

Communication

The lessons of timekeeping are part of engineering technology. In electrical engineering terms, for digital logic and data transfer, a synchronous object requires a clock signal.

Timekeeping technologies such as the GPS satellites and Network time protocol (NTP) provide real-time access to a close approximation to the UTC timescale, and are used for many terrestrial synchronization applications.

Synchronization is an important concept in the following fields: Synchronization has several subtly distinct sub-concepts:

Some uses of synchronization

While well-designed time synchronization is an important tool for creating reliable systems, excessive use of synchronization where it is not necessary can make systems less fault-tolerant, and hence less reliable.
  • Film synchronization of image and sound in sound film.
  • Synchronization is important in fields such as digital telephony, video and digital audio where streams of sampled data are manipulated.
  • Arbiters are needed in digital electronic systems such as microprocessors to deal with asynchronous inputs. There are also electronic digital circuits called synchronizers that attempt to perform arbitration in one clock cycle. Synchronizers, unlike arbiters, are prone to failure. (See metastability in electronics).
  • Encryption systems usually require some synchronization mechanism to ensure that the receiving cipher is decoding the right bits at the right time.
  • Automotive transmissions contain synchronizers which allow the toothed rotating parts (gears and splined shaft) to be brought to the same rotational velocity before engaging the teeth.
  • Synchronization is also important in industrial automation applications.
  • Time codes are often used as a means of synchronization in film, video, and audio applications.
  • Flash photography, see Flash synchronization
  • File synchronization is used to maintain the same version of files on multiple computing devices. For example, an address book on a telephone might need to be synchronized with an address book on a computer.
  • Software applications must occasionally incorporate application-specific data synchronization in order to mirror changes over time among multiple data sources at a level more granular than File synchronization. An example use of this is the Data Synchronization specification of the Open Mobile Alliance, which continues the work previously done by the SyncML initiative. SyncML was initially proposed to synchronize changes in personal address book and calendar information from computers to mobile phones, but has subsequently been used in applications that synchronize other types of data changes among multiple sources, such as project status changes.
  • The term synchronization is also sometimes used for the transfer of content from a computer to an MP3 player connected to it.

See also

In the field of video and audio engineering: In the field of aircraft gun engineering: Order synchronization and related topics: Compare with:
The X-Files is an American Peabody and Emmy Award-winning science fiction television series created by Chris Carter, which first aired on September 10, 1993, and ended on May 19, 2002.
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Synchronicity or synchronous can refer to the following meanings:
  • synchronization, the coordination of events to operate a system in unison.
  • Synchronization (computer science)
  • Synchronization (alternating current)

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time.

One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence, and time itself is something that can be measured.
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System (from Latin systēma, in turn from Greek σύστημα systēma) is a set of entities, real or abstract, where each entity interacts with, or is related to, at least one other
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Conducting is the act of directing a musical performance by way of visible gestures. Orchestras, choirs, concert bands and other musical ensembles often have conductors.
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The term Plesiochronous is derived from the Greek plesio, meaning near, and chronos, time, and refers to the fact that plesiochronous systems run in a state where different parts of the system are almost, but not quite perfectly, synchronised.
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Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its
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John Harrison (March 24 1693 – March 24 1776) was an English clockmaker who revolutionised and extended the possibility of safe long distance sea travel in the Age of Sail by inventing a long-sought and critically-needed key piece in the problem of accurately establishing the
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Electrical engineering (sometimes referred to as electrical and electronic engineering) is an engineering field that deals with the study and/or application of electricity, electronics and electromagnetism.
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clock signal is a signal used to coordinate the actions of two or more circuits. A clock signal oscillates between a high and a low state, normally with a 50% duty cycle, and is usually in the form of a square wave.
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Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its
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The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. NTP uses UDP port 123 as its transport layer. It is designed particularly to resist the effects of variable latency (jitter).
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Coordinated Universal Time (UTC) is a high-precision atomic time standard. UTC has uniform seconds defined by International Atomic Time (TAI), with leap seconds announced at irregular intervals to compensate for the earth's slowing rotation and other discrepancies.
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In computer science, synchronization refers to one of two distinct, but related concepts: synchronization of processes, and synchronization of data. Process synchronization
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Telecommunication is the transmission of signals over a distance for the purpose of communication. In modern times, this process typically involves the sending of electromagnetic waves by electronic transmitters, but in earlier times telecommunication may have involved the use of
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Physics is the science of matter[1] and its motion[2][3], as well as space and time[4][5] —the science that deals with concepts such as force, energy, mass, and charge.
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Simultaneity is the property of two events happening at the same time in at least one reference frame.

The noun Simult means a supernatural coincidence, two or more divinely inspired events that occur at or near the same period of time that are related to each other
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Cryptography (or cryptology; derived from Greek κρυπτός kryptós "hidden," and the verb γράφω gráfo "write" or λεγειν legein
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Multimedia (Lat. Multum + Medium) is media that uses multiple forms of information content and information processing (e.g. text, audio, graphics, animation, video, interactivity) to inform or entertain the (user) audience.
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Photography [fә'tɑgrәfi:],[foʊ'tɑgrәfi:] is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or electronic sensor.
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Rhythm (Greek ῥυθμός = 'flow', or in Modern Greek, 'style') is the variation of the length and accentuation of a series of sounds or other events.
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Oscillator sync is a feature in synthesizers. One oscillator will restart the period of another oscillator, so that they will have the same base frequency. The timbre can be altered on the synched oscillator by varying its frequency input.
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Phase synchronization is the process by which two or more cyclic signals tend to oscillate with a repeating sequence of relative phase angles.

Phase synchronisation is usually applied to two waveforms of the same frequency with identical phase angles with each cycle.
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IMAGE (from Imager for Magnetopause-to-Aurora Global Exploration), or Explorer 78, was a NASA MIDEX mission that studied the global response of the Earth's magnetosphere to changes in the solar wind.
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Sound is a disturbance of mechanical energy that propagates through matter as a wave (through fluids as a compression wave, and through solids as both compression and shear waves).
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sound film is a motion picture with synchronized sound, or sound technologically coupled to image, as opposed to a silent film. The first known public exhibition of projected sound films took place in Paris in 1900, but it would be decades before reliable synchronization was made
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Digital telephony is a technology used in the provision of digital telephone services and systems. Since the 1960s it has almost entirely replaced the old telephone system that used analog telephony.
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Video (Latin for "I see", first person singular present, indicative of videre, "to see") is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
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Digital audio uses digital signals for sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage, and transmission.

Digital audio has emerged because of its usefulness in the recording, manipulation, mass-production, and
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