A method includes computing electrical phase of electrical metering devices including obtaining data indicating zero-crossing times at first and second metering devices. A time difference between the zero-crossing times may be determined. In a first example, the time difference may be based at least in part on calculations involving a first value of a first free-run timer on a first metering device, a second value of a second free-run timer on a second metering device, the time of reception of a packet, and a latency defined by a time taken for the packet to propagate through at least one layer of at least one of the first metering device and the second metering device. A phase difference between the first zero-crossing and the second zero-crossing may be determined, based at least in part on the determined time difference.

A method for determining a sending period of a packet in a deterministic network and an apparatus are disclosed. The method includes: receiving a first packet; determining a first period, where the first period is a sending period of the first packet; determining timestamp information of the first packet based on the first period, where the timestamp information is used to indicate a time difference between a first time and a second time, the first time is a time at which the first packet starts to be sent in the first period, and the second time is a start time of the first period; encapsulating the timestamp information into the first packet to obtain a second packet; and sending the second packet.

A range is determined between two unsynchronized communications terminals in which a first terminal transmits a range request to a second terminal. The first terminal stores a first timestamp in memory corresponding to a time at which the range request message was transmitted. A range response is later received by the first terminal from the second terminal. The range response includes a residence time that characterizes an amount of time the second terminal required to send the range response after receiving the range request. The first terminal later stores a second timestamp in memory corresponding to a time at which the range response was received. Based on the second timestamp minus the first timestamp and the residence time, a roundtrip time for the range request is calculated. This roundtrip time can be used to calculate a distance between the first terminal and the second terminal based on the roundtrip time.

A method for performing fragmented transmission is disclosed. The method by a first ultra-wide band (UWB) device includes identifying a transport packet for fragmented transmission, obtaining a plurality of fragmented packets from the transport packet, and transmitting the plurality of fragmented packets through a UWB channel to a second UWB device at a preset transmission interval. Each of the plurality of fragmented packets may include an STS field and a fragmented payload, and the STS field may be included in a front end of the fragmented packet.

In a transceiver, the accuracy of a packet time stamp can be improved by compensating for errors introduced by processing of the packet. A received packet can be received via multiple lanes. A packet time stamp can be measured using a start of frame delimiter (SFD). A last arriving lane can be used to provide a recovered clock signal. A phase offset between the recovered clock signal and the system clock of the transceiver can be used to adjust the time stamp. A position of the SFD within a data block can be used to adjust the time stamp. A position of the data block within a combined group of data blocks can be used to adjust the time stamp. Also, a serializer-deserializer delay associated with the last arriving lane can be used to adjust the time stamp.

An approach for detecting anomalous flows in a network using header field entropy. This can be useful in detecting anomalous or malicious traffic that may attempt to “hide” or inject itself into legitimate flows. A malicious endpoint might attempt to send a control message in underutilized header fields or might try to inject illegitimate data into a legitimate flow. These illegitimate flows will likely demonstrate header field entropy that is higher than legitimate flows. Detecting anomalous flows using header field entropy can help detect malicious endpoints.

A communication system and a communication method for one-way transmission are provided. The communication method includes: receiving, by a precision time protocol switch, a first synchronization message from a grandmaster clock; generating, by the precision time protocol switch, a second synchronization message according to the first synchronization message; transmitting, by the precision time protocol switch, the second synchronization message to a transmitting server and a programmable logic device; generating, by the transmitting server, a timestamp according to the second synchronization message; transmitting, by the transmitting server, at least one data packet and the timestamp to the precision time protocol switch; forwarding, by the precision time protocol switch, the at least one data packet and the timestamp to the programmable logic device; and determining, by the programmable logic device, whether to output the at least one data packet according to the timestamp and the second synchronization message.

A method and a structure for determining a global clock among systems are disclosed. When a standardized time reference is required among systems, a reference clock source may transmit a calibration signal, and a transmitting time T.sub.d (0) may be recorded. Each system may respectively record an arrival time T.sub.a (n), transmit a return signal to a signal recording unit of the reference clock source, and record a transmitting time T.sub.b (n), after receiving the calibration signal. Similarly, because of different distances, the signal recording unit may record arrival times T.sub.d (n) of the return signals subsequently, and determine time delays Delay (n) between systems and the reference clock source respectively. When all the systems are required to have a completely standardized time reference, a corresponding Delay (n) may be acquired and transmitted to each system. Each system may determine zero deviations T.sub.c (n) of various local clocks from the reference clock source, and take T.sub.c (n) as a correction parameter to correct its own system clock, so that the local clocks of all the systems have a completely standardized time reference.

Methods, systems, and apparatus for preserving timing domains of different communications types of signals in a telecommunications network are disclosed. In one aspect a network element (NE) includes a receiver configured to receive communications signals of two different communications types. The NE can include a timing analyzer configured to obtain a local reference clock (LRC), detect two different received reference clocks (RRCs) corresponding to the two different communications types, and for each received communications signal, determine a quantized value (QV) based on a difference between the LRC and the RRC. The NE can include a timing generator configured to generate, for the received communications signal, a transmit reference clock (TRC) that is referenced to, but different from, each of the LRC and the QV. The NE can include a transmitter configured to output an output signal based on the received communications signal and the TRC for the received communications signal.

A timestamp unit and a communication control unit for a user station. The timestamp unit includes a memory, which cyclically stores a timestamp of a message, which is transmitted via a communication network, an address counter, which is incrementable with each storing of a timestamp of a message, so that the value of the address counter corresponds to an address at which the timestamp is stored in the memory, a first interface to a host control unit via which the timestamp of a message is capturable, and a second interface to a communication control unit, which creates or reads at least one message for/from the user station, the interface including a connection for receiving a trigger signal from the communication control unit, which prompts the capturing of a timestamp, and a connection for transmitting a signal to the communication control unit, which includes the value of the address counter.