A network adapter includes a network port for communicating with a communication network, a hardware clock, and circuitry. The circuitry is coupled to receive from the communication network, via the network port, one or more time-protocol packets that convey a network time used for synchronizing network devices in the communication network, to align the hardware clock to the network time conveyed in the time-protocol packets, and to make the network time available to one or more time-service consumers running in a host served by the network adapter.

A communication apparatus including a plurality of communication interfaces, a plurality of clocks, and a plurality of output units each associated with a corresponding clock, synchronizes the clocks with a time server, checks whether the clocks are in synchronization with the time server, and selects as a synchronization signal supplied to another apparatus a synchronization signal output from a corresponding output unit associated with the corresponding clock in synchronization with the time server from among the synchronization signals output from the output units. Each output unit starts outputting the signal when a time of the corresponding clock reaches a start time designated by an external apparatus, and outputs the signal when the time of the clock reaches the start time, even with the clock associated with the corresponding output unit out of synchronization with the time server.

Method for time synchronization in a network comprising masters and at least one slave. The slave receives synchronization messages from the masters via the network for time synchronization of a first clock and a second clock of the slave. A first master sends a first synchronization message having a first time stamp to the slave for time synchronization of the first clock. The slave calculates a clock rate and a time difference between the first clock and the first master and aligns the first clock with a synchronized time. A second master sends a second synchronization message having a second time stamp to the slave for the time synchronization of the second clock. The clock rate of the second clock is set to the first clock rate. A time difference between the second clock and the second master is calculated and the second clock is aligned with the synchronized time.

Methods and systems are described for receiving N phases of a local clock signal and M phases of a reference signal, wherein M is an integer greater than or equal to 1 and N is an integer greater than or equal to 2, generating a plurality of partial phase error signals, each partial phase error signal formed at least in part by comparing (i) a respective phase of the M phases of the reference signal to (ii) a respective phase of the N phases of the local clock signal, and generating a composite phase error signal by summing the plurality of partial phase error signals, and responsively adjusting a fixed phase of a local oscillator using the composite phase error signal.

One embodiment relates to a transmitting device, a receiving device, and the like for preventing increases in the number of communication links, power consumption, and circuit layout area. The transmitting device includes a high-speed signal generator, a low-speed signal generator, and a signal superimposing unit. The high-speed signal generator generates a high-speed signal having a limited frequency band. The low-speed signal generator generates a low-speed signal having a frequency lower than the frequency band of the high-speed signal. The signal superimposing unit outputs a superimposed signal of the high-speed signal and the low-speed signal. The receiving device includes a signal separator and a recovery unit. The signal separator separates the received signal into the high-speed signal and the low-speed signal. The recovery unit performs frequency tracking based on the separated low-speed signal and performs phase tracking based on the separated high-speed signal.

An object of the present invention is to provide a communication system and a communication method that can avoid network congestion using a simple approach. The communication system of the present invention is characterized in that a time distribution server that transmits time information to terminals distributes a time different from the standard time for each terminal, and the terminal performs communication on the basis of the distributed time, and further characterized in that, for a time synchronizing packet transmitted from a time distribution server on the Internet to a terminal, a node or the like in the middle of the path performs transfer control or rewrites the packet, thereby causing the terminal to recognize a different time, and the terminal performs communication on the basis of the time.

The method relates to a synchronization of a magnetic locating system including a first device and a second device each including an oscillator, a time counter clocked by the oscillator, and a radiocommunication module. The locating system also includes a device for emitting and receiving alternating magnetic fields, the device being configured to allow a propagation of alternating magnetic fields between the first and second devices, the device for emitting and receiving alternating magnetic fields being connected to the oscillators of the first and second devices. The synchronizing method includes a synchronizing step that is configured to synchronize the oscillators of the first and second devices by adjusting, by servo-controlling the oscillator of the second device, the operation of the time counter of the second device to the operation of the time counter of the first device.

A method includes, at a first node: transmitting a first calibration signal at a first time-of-departure measured by the first node; and transmitting a second calibration signal at a second time-of-departure measured by the first node. The method also includes, at a second node: receiving the first calibration signal at a first time-of-arrival measured by the second node; and receiving the second calibration signal at a second time-of-arrival measured by the second node. The method further includes: defining a first calibration point and a second calibration point in a set of calibration points, each calibration point comprising a time-of-departure and a time-of-arrival of each calibration signal; calculating a regression on the set of calibration points; and calculating a frequency offset between the first node and the second node based on the first regression.

Systems and methods are disclosed herein for performing a time-triggered distribution of messages from a region of networked machines to multiple destinations. In an embodiment, the system runs a software-based synchronization process to synchronize each of a plurality of gateways with a reference clock, wherein each gateway is a machine on a perimeter of the region of networked machines and is connected to transmit messages to multiple destinations. The gateways receive messages from within the region of networked machines for distribution to multiple destinations outside the region of networked machines according to a distribution schedule based on absolute time relative to the reference clock. The gateways perform the distribution of received messages, wherein each gateway determines absolute time based on that gateway's synchronization with the reference clock.

A communication apparatus includes a first counter configured to synchronize with a reference time, a second counter configured to synchronize with the first counter, a generation unit configured to generate a synchronization signal each time when a value of the second counter is incremented by a predetermined number, a correction unit configured to correct the value of the second counter toward a value of the first counter, and a control unit configured to control the correction unit to cause the correction unit to calculate a difference between the value of the first counter and the value of the second counter and, in a case where the calculated difference is greater than a predetermined threshold value, the correction unit to correct the value of the second counter step by step.