A grand master device (GM) (10) and a slave device (S1) (20) are connected via a general-purpose hub (HUB) (30) whose relay delay is not constant. The grand master device (GM) (10), at a timing for transmitting a Sync frame for time synchronization, acquires current time as transmission time of the Sync frame, acquires a count value of a master counter as a transmission count value, stores the transmission time and the transmission count value in the Sync frame, and transmits the Sync frame. The slave device (S1) (20) receives the Sync frame, acquires reception time of the Sync frame and a reception count value which is a count value of a slave counter at the reception time, and corrects time of the slave device (S1) (20), using the transmission time, the transmission count value, the reception time and the reception count value.

A method of a reception apparatus for receiving transmission frames. The method includes receiving, by circuitry of the reception apparatus, the transmission frames transmitted on one millisecond boundaries. Each of the transmission frames includes a bootstrap, a preamble, and a payload. The method further includes determining, by the circuitry, an absolute point of time at a predetermined position in a stream of the transmission frames based on first time information included in a first one of the transmission frames.

Compact timestamps and related methods, systems and devices are described. An encoder is configured to generate compact timestamps of the disclosure by sampling states of linear feedback shift registers (LFSRs). A decoder may be configured to determine timing information responsive to the compact timestamps.

There is provided a technique of clock managing in a packet data network implementing a time-transfer protocol. The technique comprises: modifying, by the timing-server, a timestamp record to enable a controllable access to data informative of the least significant part of clock-informative data (CLSP data), wherein modifying the timestamp record comprises modifying the least significant part of the timestamp record (RLSP) to comprise the CLSP data in an encrypted form or to comprise values substituting, in a predefined manner, the CLSP data; transferring the modified timestamp record to all timing-clients, wherein CLSP data are transferred in a controllable access manner; enabling access to the CLSP data merely to authorized timing-clients among the plurality of timing-clients; and enabling the authorized timing-clients to obtain the CLSP data and synchronize the respective clocks using the CLSP data together with data informative of the most significant part of the clock-informative data.

The disclosure relates to method and system for correcting a clock skew in a slave device using a precision time protocol (PTP). The method includes determining an uplink delay and a downlink delay, based on at least two packet transactions in the PTP protocol and conducted between the slave device and a master device within a pre-defined accumulator time window. The method further includes determining a change in the uplink/downlink delay with respect to a reference uplink/downlink delay. The reference uplink/downlink delay correspond to a first pre-defined accumulator time window at a start of the slave device, or to a last pre-defined accumulator time window during a previous correction of the clock skew. The method further includes correcting the clock skew upon determining the change in the uplink delay to be about same in magnitude as and to be in opposite direction to the change in the downlink delay.

A frequency synchronization method includes: receiving, by a slave clock, a first pulse signal and a second pulse signal; determining, by the slave clock based on a first phase difference, a second phase difference, a first delay, and a second delay, that a frequency offset of the slave clock relative to the master clock is equal to a first frequency offset, where the first phase difference is a difference between a phase of a third pulse signal generated by the slave clock and a phase of the first pulse signal received by the slave clock, and the second phase difference is a difference between a phase of a fourth pulse signal generated by the slave clock and a phase of the second pulse signal received by the slave clock; and calibrating, by the slave clock, frequency of the slave clock based on the first frequency offset.

A bitstream representing an Ethernet frame is received over a physical medium. Encoded Ethernet blocks are recovered from the bitstream. The Ethernet blocks are descrambled and provided to downstream switching logic, intact, without removing the synchronization bits that were added during the encoding process. More particularly, the intact descrambled Ethernet block is divided into smaller-sized data words; the size of the data words being an integer multiple of the size of the Ethernet block.

According to an embodiment, in a network system 1 in which at least one data of the audio data and the video data is transmitted from a first node to a second node through a network, the second node includes a processor configured to generate a clock signal for reproduction of the audio data and the like. The processor is configured to synchronize a current time in the second node with a current time in the first node, based on a transmission time that is based on the current time in the first node and is contained in a received extended CRF frame, a reception time that is based on the current time in the second node and at which the extended CRF frame is received, and a delay time period occurring while the extended CRF frame is transmitted from the first node to the second node.

This disclosure describes techniques for delivering high-accuracy and high-precision clock synchronization in heterogeneous distributed computer clusters. For example, the disclosure describes a synchronization engine that sets efficient clock synchronization processes based on a cluster node's characteristics, pricing, precision, geolocation, and/or cluster topology, while in some cases using a combination of master clock data with internal atomic clocks of computers. The techniques described herein integrate the synchronization engine into a time synchronization process that may provide stability, versatility, precision and cost balance using technical improvements for characterizing timing system delivery channels.

A high definition timing synchronization function is described. In an embodiment, a wireless station generates a time stamp at a higher resolution than can be broadcast within a standard time stamp field in a frame. The generated time stamp is divided into two parts: the first part being included within the time stamp field and the second part being included within a vendor specific field in the same frame. The frame is transmitted by the wireless station and received by other wireless stations in the wireless network. If the receiving wireless station has the capability, it decodes both the time stamp field and the vendor specific field and recreates the higher resolution time stamp. This higher resolution time stamp is then used to synchronize the receiving wireless station and the transmitting wireless station by resetting a clock or by storing time stamps and corresponding clock values.