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Synchronization or synchronisation is timekeeping which requires the coordination of events to operate a system
System

System is a set of interacting or interdependent entities, real or abstract, forming an integrated whole.The concept of an "integrated whole" can also be stated in terms of a system embodying a set of relationships which are differentiated from relationships of the set to other elements, and from relationships between an element of the se...
 in unison. The familiar conductor
Conducting

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....
 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
Plesiochronous

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, synchronization....
. 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
Global Positioning System

The Global Positioning System is a global navigation satellite system developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing....
-enabled timekeeping systems.

t from its use for navigation (see John Harrison
John Harrison

John Harrison was a self-educated England clockmaker. He invented the marine chronometer, a long-sought and critically-needed key piece in solving the problem of accurately establishing the East-West position, or longitude, of a ship at sea, thus revolutionising and extending the possibility of safe long distance sea travel in the Age of Sai...
), 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 ).

In some territories, sharing of single railroad tracks was controlled by the timetable.






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Synchronization or synchronisation is timekeeping which requires the coordination of events to operate a system
System

System is a set of interacting or interdependent entities, real or abstract, forming an integrated whole.The concept of an "integrated whole" can also be stated in terms of a system embodying a set of relationships which are differentiated from relationships of the set to other elements, and from relationships between an element of the se...
 in unison. The familiar conductor
Conducting

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....
 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
Plesiochronous

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, synchronization....
. 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
Global Positioning System

The Global Positioning System is a global navigation satellite system developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing....
-enabled timekeeping systems.

Transport

Apart from its use for navigation (see John Harrison
John Harrison

John Harrison was a self-educated England clockmaker. He invented the marine chronometer, a long-sought and critically-needed key piece in solving the problem of accurately establishing the East-West position, or longitude, of a ship at sea, thus revolutionising and extending the possibility of safe long distance sea travel in the Age of Sai...
), 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 ).

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
Electrical engineering

Electrical engineering, sometimes referred to as electrical and electronic engineering, is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism....
 terms, for digital logic and data transfer, a synchronous object requires a clock signal
Clock signal

In electronics and especially Synchronous logic digital circuits, a clock signal is a Signalling used to coordinate the actions of two or more Electronic circuit....
. TEST123 Timekeeping technologies such as the GPS
Global Positioning System

The Global Positioning System is a global navigation satellite system developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing....
 satellites and Network time protocol
Network Time Protocol

The Network Time Protocol is a protocol for clock synchronization of computer systems over packet-switched, variable-Latency data networks. NTP uses User Datagram Protocol on TCP and UDP port 123 as its transport layer....
 (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:
  • Computer science
    Synchronization (computer science)

    In computer science, synchronization refers to one of two distinct but related concepts: synchronization of process , and synchronization of data....
     (In computer science, especially parallel computing, synchronization refers to the coordination of simultaneous threads or processes to complete a task; in order to obtain correct runtime order and avoid unexpected race conditions.)
  • Telecommunication
    Telecommunication

    Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
  • Physics
    Physics

    Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
     (The idea of simultaneity
    Simultaneity

    Simultaneity is the properties of two Spacetime#Basic conceptss 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 in both noticeable and unnoticeable characteristi...
     has many difficulties, both in practice and theory.)
  • Cryptography
    Cryptography

    Cryptography is the practice and study of hiding information. In modern times cryptography is considered a branch of both mathematics and computer science and is affiliated closely with information theory, computer security and engineering....
  • Multimedia
    Multimedia

    Multimedia is media and content that utilizes a combination of different content format. The term can be used as a noun or as an adjective describing a medium as having multiple content forms....
  • Photography
    Photography

    Photography is the process, activity and art of creating still or moving by recording radiation on a sensitive medium, such as a photographic film, or an ....
  • Music
    Music

    Music is an art form whose media is sound organized in time. Common elements of music are pitch , rhythm , dynamics , and the sonic qualities of timbre and texture ....
     (rhythm
    Rhythm

    Rhythm is the variation of the length and accentuation of a series of sounds or other events....
    )
  • Synthesizers
    Oscillator sync

    Oscillator sync is a feature in synthesizers. One oscillator will restart the period of another oscillator, so that they will have the same frequency....


Synchronization has several subtly distinct sub-concepts:
  • Rate synchronization
  • Phase synchronization
    Phase synchronization

    Phase synchronization is the process by which two or more cyclic signals tend to oscillate with a repeating sequence of relative phase angles....
  • Time offset synchronization
  • Time order synchronization


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.
  • mobile phone synchronization using -standards or java based technology to perform a backup on a phone.
  • Film synchronization of image
    Image

    An image is an artifact, usually two-dimensional , that has a similar appearance to some subject —usually a physical object or a person....
     and sound
    Sound

    Sound is vibration transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a threshold of hearing to be heard, or the sensation stimulated in organs of hearing by such vibrations....
     in sound film
    Sound film

    A sound film is a film with synchronization, 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 decades would pass before reliable synchronization was made commercially practical....
    .
  • Synchronization is important in fields such as digital telephony
    Digital telephony

    Digital telephony is the use of digital electronics in the provision of digital telephone services and systems. Since the 1960s a digital core network has almost entirely replaced the old Analog signal system, and much of the access network has also been digitized....
    , video
    Video

    Video is the technology of electronics Videography, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing Scene in motion....
     and digital audio
    Digital audio

    Digital audio uses digital signals for sound reproduction. This includes Analog-to-digital converter, Digital-to-analog converter, storage, and transmission....
     where streams of sampled data are manipulated.
  • Arbiters
    Arbiter (electronics)

    Arbiters are electronic devices that allocate access to shared resources....
     are needed in digital electronic systems such as microprocessor
    Microprocessor

    A microprocessor incorporates most or all of the functions of a central processing unit on a single integrated circuit . The first microprocessors emerged in the early 1970s and were used for electronic calculators, using Binary-coded decimal arithmetic on 4-bit Word ....
    s 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
    Metastability in electronics

    Metastability in electronics is the ability of a non-equilibrium electronic state to persist for a long period of time . Note this definition does not guarantee all of the properties that are sometimes demanded for a metastable state in statistical mechanics....
    ).
  • Encryption
    Encryption

    In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key ....
     systems usually require some synchronization mechanism to ensure that the receiving cipher is decoding the right bits at the right time.
  • Automotive transmission
    Transmission (mechanics)

    Using the principle of mechanical advantage, transmissions provide a speed-torque conversion from a higher speed motor to a slower but more forceful output or vice-versa....
    s 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 code
    Time code

    A time code is a sequence of numeric codes generated at regular intervals by a timing system. Time codes are used extensively for synchronization, and for logging material in recorded media....
    s are often used as a means of synchronization in film
    Film

    Film encompasses individual motion pictures, the field of film as an art form, and the film industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or special effects....
    , video
    Video

    Video is the technology of electronics Videography, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing Scene in motion....
    , and audio
    Sound

    Sound is vibration transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a threshold of hearing to be heard, or the sensation stimulated in organs of hearing by such vibrations....
     applications.
  • Flash photography
    Photography

    Photography is the process, activity and art of creating still or moving by recording radiation on a sensitive medium, such as a photographic film, or an ....
    , see Flash synchronization
    Flash synchronization

    In a camera, flash synchronization is defined as the firing of a flash coinciding with the shutter admitting light to photographic film or electronic ....
  • File synchronization
    File synchronization

    File synchronization in computing is the process of making sure that two or more locations contain the same up-to-date Computer file. If you add, change, or delete a file from one location, the synchronization process will add, change, or delete the same file at the other location....
     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
    Data synchronization

    Data synchronization is the process of establishing consistency among data on remote sources and the continuous harmonization of the data over time....
     in order to mirror changes over time among multiple data sources at a level more granular than File synchronization
    File synchronization

    File synchronization in computing is the process of making sure that two or more locations contain the same up-to-date Computer file. If you add, change, or delete a file from one location, the synchronization process will add, change, or delete the same file at the other location....
    . An example use of this is the specification of the Open Mobile Alliance
    Open Mobile Alliance

    The Open Mobile Alliance is a standards body which develops open standards for the mobile phone industry....
    , which continues the work previously done by the SyncML
    SyncML

    SyncML is the former name for a platform-independent information synchronization standard. Existing synchronization solutions have mostly been somewhat vendor-, application- or operating system specific....
     initiative. SyncML
    SyncML

    SyncML is the former name for a platform-independent information synchronization standard. Existing synchronization solutions have mostly been somewhat vendor-, application- or operating system specific....
     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 .
  • The term synchronization is also sometimes used for the transfer of content from a computer to an MP3
    MP3

    MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a digital audio Encoder format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard encoding for the transfer and playback of music on digital audio players....
     player connected to it.


See also

  • Asynchrony
    Asynchrony

    Asynchrony, in the general meaning, is the state of not being synchronization.* Asynchronous learning* Collaborative editing systemsIn specific terms of digital logic and physical layer of communication, an asynchronous process does not require a clock signal....
  • Clock synchronization
    Clock synchronization

    Clock synchronization is a problem from computer science and engineering which deals with the idea that internal clocks of several computers may differ....
  • Entrainment
    Entrainment

    Entrainment may refer to:* Air entrainment, the intentional creation of tiny air bubbles in concrete* Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency...
  • Flywheel
    Flywheel

    A flywheel is a mechanical device with significant moment of inertia used as a storage device for rotational energy. Flywheels resist changes in their rotational speed, which helps steady the rotation of the shaft when a fluctuating torque is exerted on it by its power source such as a piston-based engine, or when the load placed on it is...
  • Homochronous
    Homochronous

    In telecommunication, the term homochronous describes the relationship between two Signalling ssuch that their corresponding significant instants are displaced by a constant interval of time....
  • Mutual exclusion
    Mutual exclusion

    Mutual exclusion algorithms are used in concurrent programming to avoid the simultaneous use of a common resource, such as a global variable, by pieces of computer code called critical sections....
  • Phase-locked loop
    Phase-locked loop

    A phase-locked loop or phase lock loop is a control system that generates a Signal that has a fixed relation to the phase of a "reference" signal....
    s
  • Reciprocal socialization
    Reciprocal socialization

    Reciprocal socialization is a socialization process that is bidirectional; children socialize parents just as parents socialize children. For example, the interaction of mothers and their infants is sometimes symbolized as a dance or dialogue in which following actions of the partners are closely coordinated....
  • Synchronism
    Synchronism

    Synchronism is deliberately achieved coincidence in a point of time.In telecommunication the term synchronism has the following meanings:...
  • Synchronization (alternating current)
    Synchronization (alternating current)

    Synchronization is an important concept in relation to alternating current....
  • Synchronization in telecommunications
    Synchronization in telecommunications

    Many services running on modern digital telecommunications networks require accurate synchronization for correct operation. For example, If switches do not operate with the same rate clocks then slips will occur degrading performance....
  • Synchronization of chaos
    Synchronization of chaos

    Synchronization of chaos is a phenomenon that may occur when two, or more, chaos theory are coupled, or when a chaotic oscillator drives another chaotic oscillator....
  • Synchronizer
  • Synchronous conferencing
    Synchronous conferencing

    Synchronous conferencing is the formal term used in science, in particular in computer-mediated communication, Computer-supported collaboration and Web-based training, to describe online chat technologies....
  • Time
    Time

    Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
  • Timing Synchronization Function (TSF)
    Timing Synchronization Function (TSF)

    Timing Synchronization Function is specified in IEEE 802.11 WLAN standard to fulfill timing synchronization among users. A Timing Synchronization Function keeps the timers for all Station_ in the same Basic_Service_Set synchronized....
  • Time transfer
    Time transfer

    Time transfer describes methods for transferring reference clock synchronization from one point to another, often over long distances. Radio navigation are frequently used as time transfer systems....
  • Timecode


In the field of video and audio engineering:
  • Genlock
    Genlock

    Genlock is a common technique where the video output of one source, or a specific reference signal, is used to synchronization other television picture sources together....
  • Jam sync
    Jam sync

    Jam sync refers to the practice of applying a phase hit to a system to bring it in synchronization with another. The term originates from the use of this technique to replace defective time code on a video tape recording by replacing it with a new time code sequence, which may be an extension of a previous good time code sequence on an earlie...
  • Word sync
    Word sync

    Word sync is a technique for synchronizing digital audio signals between high-end professional devices such as CD players, audio I/O cards etc....


In the field of aircraft gun engineering:
  • Interrupter gear
    Interrupter gear

    Interrupter gear is a term that covers two related technologies.The first is the synchronization gear, which is often incorrectly referred to as "interrupter gear"; this is a triggering device attached to the machine gun armament of a tractor -type fighter aircraft so that it would fire only at certain times....


Order synchronization and related topics:
  • Rendezvous problem
    Rendezvous problem

    The rendezvous dilemma is related to the prisoner's dilemma and can be formulated in this way:If they both choose to wait, of course, they will never meet....
  • Interlocking
    Interlocking

    In railway signaling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings....
  • Race condition
    Race condition

    A race condition or race hazard is a flaw in a system or process whereby the output and/or result of the process is unexpectedly and critically dependent on the sequence or timing of other events....
  • Concurrency control
    Concurrency control

    In computer science, especially in the fields of computer programming , operating systems , multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, while getting those results as quickly as possible....
  • Room synchronization
    Room synchronization

    The room synchronization technique is a form of concurrency control in computer science.The room synchronization problem involves supporting a set of m mutually exclusive "rooms" where any number of users can execute code simultaneously in any one of the rooms, but no two users can simultaneously execute code in separate rooms....
  • Transient blocking synchronization
  • Comparison of synchronous and asynchronous signalling
    Comparison of synchronous and asynchronous signalling

    Synchronous and asynchronous transmissions are two different methods of transmission synchronization. Synchronous transmissions are synchronized by an external clock, while asynchronous transmissions are synchronized by special signals along the transmission medium....


Compare with:
  • Synchronicity
    Synchronicity

    Synchronicity is the experience of two or more Event which are Causality occurring together in a supposedly Meaning manner. In order to count as synchronicity, the events should be unlikely to occur together by chance....
    , a mystical notion due to Carl Jung
    Carl Jung

    Carl Gustav Jung was a Swiss psychiatrist, an influential thinker and the founder of Analytical psychology. Jung's approach to psychology has been influential in the field of depth psychology and in counterculture movements across the globe....
    .