A system is described for maintaining synchrony of operations among a plurality of devices having independent clocking arrangements. A task distribution device is to distribute tasks to a synchrony group comprising a plurality of devices to perform tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to synchrony group members over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which synchrony group members are to execute the task. Each synchrony group member periodically obtains from the task distribution device an indication of current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task.

System and method for synchronizing operations among a plurality of independently clocked digital data processing devices

In general, user interfaces for controlling a plurality of multimedia players in groups are disclosed. According to one aspect of the present invention, a user interface is provided to allow a user to group some of the players according to a theme or scene, where each of the players is located in a zone. When the scene is activated, the players in the scene react in a synchronized manner. For example, the players in the scene are all caused to play a multimedia source or music in a playlist, wherein the multimedia source may be located anywhere on a network. The user interface is further configured to illustrate graphically a size of a group, the larger the group appears relatively, the more plays there are in the group.

User Interfaces for Controlling and Manipulating Groupings in a Multi-Zone Media System

White Rabbit (WR) is the project name for a ambiguous project that uses Ethernet as both, deterministic (synchronous) data transfer and timing network. The presented design aims for a general purpose, fieldbus like transmission system, which provides deterministic data and timing to approximately 1000 timing stations. The main advantage over conventional systems is the highly accurate timing (sub-nanosecond range) without restrictions on the traffic schedule and an upper bound for the delivery time of high priority messages. In addition, WR also automatically compensates for transmission delays in the fibre links, which are in the range of 10 km length. It takes advantage of the latest developments on synchronous Ethernet and IEEE 1588 to enable the distribution of accurate timing information to the nodes saving noticeable amounts of bandwidth.

White rabbit: Sub-nanosecond timing distribution over ethernet

Embodiments are provided for syncing multiple electronic devices for collective audio playback. According to certain aspects, a master device connects (218) to a slave device via a wireless connection. The master device calculates (224) a network latency via a series of network latency pings with the slave device and sends (225) the network latency to the slave device. Further, the master devices sends (232) a portion of an audio file as well as a timing instruction including a system time to the slave device. The master device initiates (234) playback of the portion of the audio file and the slave devices initiates (236) playback of the portion of the audio file according to the timing instruction and a calculated system clock offset value.

Systems and methods for syncronizing multiple electronic devices

Example systems, apparatus, and methods receive audio information including a plurality of frames from a source device, wherein each frame of the plurality of frames includes one or more audio samples and a time stamp indicating when to play the one or more audio samples of the respective frame. In an example, the time stamp is updated for each of the plurality of frames using a time differential value determined between clock information received from the source device and clock information associated with the device. The updated time stamp is stored for each of the plurality of frames, and the audio information is output based on the plurality of frames and associated updated time stamps. A number of samples per frame to be output is adjusted based on a comparison between the updated time stamp for the frame and a predicted time value for play back of the frame.

Systems and methods for synchronizing operations among a plurality of independently clocked digital data processing devices without a voltage controlled crystal oscillator

The invention relates to a method for synchronizing a communications cycle and a communications node in a network Said node comprises: devices for receiving a desired value for a time base of a communications cycle of the communications node in a communications link to an additional communications node of the network; devices for determining a system deviation between the desired value and an actual value of the time base; and a device for generating a manipulated variable for correcting the time base in accordance with the system deviation

Communications system and method for synchronizing a communications cycle

This paper analyzes the factors that affect the synchronization performance in using the precision time protocol (FTP). We first study the influence of jitter under the assumption of no frequency drifts. Then we study the influence of frequency drift in the absence of jitter. The analytic formulas provide a theoretical ground for the understanding of simulation results as well as guidelines for choosing both system and control parameters when applying FTP.

Synchronization Performance of the Precision Time Protocol

Upon reception of a message (N) which is relevant to synchronization, the circuitry in a device (M, S) forms a piece of reception-time information (tSE, tME), and this information is inserted into or appended to the received message (N) and forwarded such that the reception-time information (tSE/tME) can be received by at least one synchronization application (PTP) in the device (M, S). When a message (N) is transmitted, the circuitry in the device (M, S) forms a piece of transmission-time information (tST, tMT), and this information is sent to at least one synchronization application (PT) initializing the message (N) in the device (M, S). A fundamental advantage can be seen in that the economic outlay, particularly the outlay in terms of circuitry, for implementing the synchronization of the clocks and the determination of the communication-network or transmission-medium delay times, particularly on the basis of the IEEE standard 1588, is substantially reduced.

Methods and devices for sending transmission-time or reception-time information for a transmitted or received message

The invention relates to a method for transmitting real time data messages in a cyclic communications system, each transmission cycle having a first partial cycle (IRT-Z.) for the real time communication and a second partial cycle (NRT-Z.) for the non-real time communication. Said method comprises the following steps: determination (118) of a cycle number; processing of a transmission sequence of real time data messages in the first partial cycle, whereby the transmission sequence is composed of one or more partial sequences (1, 2, 3, 4, 5) and the composition depends on the cycle number.

Method for transmitting real time data messages in a cyclic communications system

Die Erfindung betrifft ein Verfahren und ein System zur Ubertragung von Daten mit einem ersten Datennetz 1 mit ersten Mitteln zur Ubertragung von Daten in wenigstens einem ersten Ubertragungszyklus, wobei der erste Ubertragungszyklus in einen ersten Bereich 4 zur Ubertragung von echtzeitkritischen Daten und einen zweiten Bereich 5 zur Ubertragung von nichtechtzeitkritischen Daten unterteilt ist, und mit einem zweiten Datennetz 2 mit zweiten Mitteln zur Ubertragung von Daten in wenigstens einem zweiten Ubertragungszyklus, wobei der zweite Ubertragungszyklus in einen dritten Bereich 7 zur Ubertragung von echtzeitkritischen Daten und in einen vierten Bereich 8 zur Ubertragung von nichtechtzeitkritischen Daten unterteilt ist, und mit einer Koppeleinheit 13 zur Ubertragung von echtzeitkritischen Daten des ersten Bereichs in den dritten Bereich.

Franz-Josef Goetz

Papers

Communications system and method for synchronizing a communications cycle

Synchronization Performance of the Precision Time Protocol

Methods and devices for sending transmission-time or reception-time information for a transmitted or received message

Method for transmitting real time data messages in a cyclic communications system

Verfahren und system zur kopplung von datennetzen