A ranging method for an optical network, an OLT, an ONU, and an optical network system are provided. The OLT sends a bandwidth allocation message to the ONU; an OLT receiving a response message sent by an ONU in a first sending mode, wherein the first sending mode comprises sending power and a transmission rate; and the OLT performs ranging on the ONU according to the response message.

A packet processing method includes receiving a first packet by a first receiving interface of a media conversion module of a first network device, where the first packet includes a first alignment marker (AM), sending a second packet by a first sending interface of the media conversion module, where the second packet includes the first AM, and where the second packet is the first packet processed by the media conversion module, and calculating a time interval T.sub.1 between a time at which the media conversion module receives the first packet and a time at which the media conversion module sends the second packet, where the T.sub.1 is used to compensate for a first timestamp at which the first network device receives or sends the third packet.

A method includes communicating first and second signals between a first node and a second node, where the first signal includes a sonic signal and the second signal includes an electromagnetic signal. The method also includes using the electromagnetic signal to one of start or stop a timer and using the sonic signal to another of stop or start the timer. The method further includes identifying a one-way time-of-flight associated with the sonic signal traveling between the first and second nodes using the timer. The one-way time-of-flight associated with the sonic signal is indicative of a distance between the nodes.

The present disclosure provides systems and methods for timestamping events on edge devices. A trusted source measures the latency to the edge device and the edge device's clock offset, and stores the information at the trusted source for later use. The trusted source sends the latency and the device's clock offset to the edge device for later use. The trusted source or the edge device adjusts a timestamp generated at the edge device using an estimated clock offset. The estimated clock offset is determined by extrapolation or interpolation from measured clock offsets.

Embodiments of a device and method are disclosed. In an embodiment, a physical layer (PHY) device for a network includes a transmitter configured to transmit data at the PHY device from a host to an external network, a host interface configured to receive the data to transmit from the host and configured to receive configuration commands from the host, a clock independent of a host clock and coupled to the host interface to receive phase and frequency adjustments as configuration commands from the host, a modulus counter to count timing pulses of the clock, and a timing output interface coupled to the modulus counter to produce a precision timing output signal based on the time stamping clock.

In one embodiment, a method receives a first time from a network device. The first time is derived from a first timing source in a first domain. The method receives a second time in a second domain from a second timing source. A difference time value is calculated between the first time and the second time. The method then sends the difference time value to the network device where the network device uses the difference time value to send a delay value to other computing devices to synchronize timing of the other computing devices in the second domain. The other computing devices are configured to synchronize the respective time using the delay value with mobile network devices to allow timing synchronization between the mobile network devices.

The present disclosure relates to an optical line terminal, OLT, which is enabled to range optical network units, ONUs, in a point-to-multipoint optical network by detecting interference burst sequences transmitted by one or more joining ONUs during transmission of upstream data traffic from transmitting ONUs. The present disclosure further relates to an optical network unit, ONU, which is enabled to transmit, at a selected transmission time, an interference burst sequence including a sequence of pulses allowing the OLT to identify the ONU as a joining ONU.

System and method for synchronizing a plurality of nodes to a timing signal using a daisy-chain network having a forward transmission path and a reverse transmission path connected at a midpoint. Latency of the timing signal to the midpoint of the daisy-chain network is determined, a respective latency of the timing signal from the node to the midpoint of the daisy-chain network is determined, and a respective timing offset for each of the plurality of nodes is calculated. A local time-of-day counter at each of the plurality of nodes is adjusted based upon the respective timing offset of the node to synchronize the plurality of nodes to the timing signal.

A control method and a time aware bridge device for a seamless Precision Time Protocol (PTP) are provided. The control method includes: utilizing the time aware bridge device to pre-configure a first control signal source as a master control signal source, and pre-configure a second control signal source as a backup control signal source; utilizing the time aware bridge device to determine whether one or more packets from the master control signal source conform to at least one predetermined rule to generate a determination result; and selectively configuring the second control signal source as the master control signal source according to the determination result.

[Problem] To determine a time difference between clocks which, for example, are placed far apart from each other with high accuracy at low cost.

[Solution] In a time comparison system 20, an intermediate station 21 disperses a single optical signal 21c in the spatial region using the optical complex amplitude modulation to simultaneously transmit the optical signal 21c to a plurality of comparative stations 22 and 23 apart from each other. The intermediate station 21 transmits the optical signal 21c while changing the transmission angle using phase modulation, performs intensity scanning for the reflected light c1 of the optical signal 21c, and detects the peak intensity to determine the directions of the comparative stations 22 and 23. The reflected light c1 of the optical signal 21c transmitted to the comparative stations 22 and 23 of which the direction have been determined, is detected to determine a round-trip propagation delay time between the intermediate station 21 and each of the comparative stations 22 and 23. The difference calculation unit 25 calculates a sum of time difference between each of times to and tb associated with the comparative stations 22 and 23 and the time tc associated with the intermediate station 21, and the determined propagation delay time to determine time information of each of the comparative stations 22 and 23. Based on the result of subtracting, from the time information of the comparative stations 22, the time information of the comparative stations 23, the time difference between the comparative stations 22 and 23 is determined.