A clock port attribute recovery method includes a network device setting a value of a port attribute of a clock port of the network device to a first value based on the clock port not receiving any one of three types of clock messages: N synchronization messages, follow-up messages, and delay response messages within a timeout interval, where the first value indicates that a message is lost on the clock port. Based on a case that a recovery condition is met, the network device sets the value of the port attribute of the clock port to a second value, where the second value indicates that a status of the clock port is that the message is not lost.

A communication system includes: a plurality of sensor terminals each including a clock indicating an individual time and configured to detect sensing information related to a user and information detection time at which the sensing information has been detected; a management terminal configured to retain a reference time and adapted to communicate with the plurality of sensor terminals; and a relationship analysis unit configured to analyze a relationship among the users of the plurality of sensor terminals, in which the management terminal acquires the sensing information and the information detection time from each of the plurality of sensor terminals and corrects the information detection time acquired from each of the plurality of sensor terminals based on a lag between the individual time acquired from the corresponding sensor terminal and the reference time, and the relationship analysis unit analyzes the relationship using the sensing information and the corrected information detection time.

A system and method capable of transporting phase and frequency synchronization over traditional IP/MPLS networks, making end terminals requiring signals received from satellites to have phase and frequency synchronisation obsolete. The method includes switching of PPS signal by DTM protocol, transmission of PPS signal to the other end of network through a virtual circuit, switching the transmitted PPS signal again by DTM protocol, conversion of PPS signal arriving at the other end to ToD and PTP data and transmission thereof to a terminal component. The system includes a transmitter mechanism converting ToD and PTP data into PPS signal on one end of the network and then switching by DTM protocol, a receiver mechanism switching PPS signal at DTM protocol on the other end of the network and converting into ToD and PTP data and transmitting to the end component, and a virtual circuit providing carriage of PPS signal.

There is provided a method and device for forwarding a digital signal arranged into portions that each contain a timestamp and an error detection code. Duplicates of the digital signal are received on a first optical path and a second, separate optical path. Corresponding timestamps are identified in the signals and used to synchronize corresponding portions of the signals. The error detection codes in the synchronized portions are used to allow one and only one of the corresponding portions to be selected for forwarding. The selected portions are then forwarded.

An optical module for use in an optical system is disclosed, the optical module implementing Precision Time Protocol (PTP) clock functionality therein. The optical module includes an electrical interface with the optical system; circuitry connected to the electrical interface and configured to implement a plurality of functions of functionality; an optical interface connected to the circuitry; and timing circuitry connected to the electrical interface and one or more of the plurality of functions, wherein the timing circuitry is configured to implement the PTP clock functionality.

An on-board communication system includes an optical coupler that includes multiple optical transmission lines, and multiple on-board devices that are capable of communicating with each other with the optical coupler interposed therebetween.

An operation method of a first communication node in an Ethernet-based vehicle network includes identifying a link status between the first communication node and each of a plurality of communication nodes included in the vehicle network; receiving a first frame from a second communication node whose link status is normal among the plurality of communication nodes; identifying a first time difference between a local time of the first communication node and a time stamp of the first frame; and determining a synchronization error between the first communication node and the second communication node based on the first time difference.

The present invention relates to a method for synchronizing the clocks of the node computers of a distributed real-time system with an external time reference, such as GPS time, requiring minimal energy expenditure, and for structuring a sparse time-base. By considering the influence of changing physical environmental parameters on the period of oscillation of local oscillators, the holdover interval, according to which an external synchronization must occur, can be dynamically determined and the frequency of the energy-intensive external synchronization processes can be significantly reduced.

Disclosed is a method comprising obtaining a plurality of previous clock skews, a reported temperature and a reported time, based on the plurality of previous clock skews, the reported temperature and the reported time, obtaining a prediction of the current clock skew, determining a current clock offset based on the predicted current clock skew, determining a clock adjustment based on the current clock offset and the reported time, and determining a corrected time based on the clock adjustment.

The disclosure provides methods, apparatus and computer-readable media for synchronization over an optical network. A method comprises: receiving, from a client, a request to initiate a synchronization service for a client node coupled to the optical communication network; and, in response to the request, establishing a synchronization service to the client node via a virtual synchronization network utilizing the optical communication network. The synchronization service utilizes a bidirectional optical channel established via the optical communication network for the transmission of synchronization data for the client.