59results about How to "Improve Clock Synchronization Accuracy" patented technology

A low-power media access control method of node dynamic sleeping includes the following steps: (1) organizing the network topology to clustering topology and realize a coarse-grained clock synchronization between the node inside the cluster and the cluster head and make the node work and sleep periodically; (2) the nodes have three operating modes: a sending mode, a receiving mode and a cycle work mode, wherein the node of the cycle work mode is characterized in that the nodes work or sleep periodically and the actual work and sleep time period of the nodes changes dynamically and the operation sub-time-period of the neighboring node can be calculated; (3) in one work cycle, the operation sub-time-period of any two adjacent nodes can be overlapped to guarantee the communication; (4) the node can intercept the packet sent by the adjacent node and adjust the sleep time period according to the information carried by the packet to reduce the carrier interception times; (5) dynamically adjusting the busy and idle degree of the node according to different data sampling rates so as to reduce the power consumption while guaranteeing the throughput. The method, which is simple and reliable, has advantages of low power consumption, short delay, strong adaptive capacity and effectively prolonged life cycle of the network.

The invention discloses a method for synchronizing time in a wireless ad hoc network based on a protocol of an institute of electrical and electronic engineers (IEEE) 1588 and aims to solve the technical problem that the time synchronization accuracy is low by the conventional time synchronization method. According to the technical scheme, the method comprises the following steps of: initializing the whole network to determine a master time node and a slave time node; performing delay measurement on time synchronization communication between the master time node and the slave time node to obtain master-slave communication delay, slave-master communication delay and unidirectional delay between the master time node and the slave time node; performing amplitude limiting filtering on the unidirectional delay in a state of a minimum withdrawn window, and performing filtering estimation on the unidirectional delay subjected to amplitude limiting through a first-order infinite impulse response filter; and calculating time deviation between the master node and the slave, and performing optimal estimation on the time deviation according to a discrete linear Kalman filtering algorithm. By the method, the time deviation stability of the time in the wireless ad hoc network is guaranteed, and the time synchronization accuracy is relatively high.

The invention relates to VR positioning and tracking technology field, in particular to an ultra-wideband positioning based VR positioning and tracking system and its positioning and tracking method. The system comprises three or more ultra-wideband positioning base stations, and is characterized by comprising VR basic equipment and a basic VR runtime. Each ultra-wideband positioning base station comprises a base station code ID generation unit, a time synchronization unit, a data processing unit, an ultra wideband (UWB) transceiver, a high accuracy clock, an antenna and a network data transmission unit. The VR basic device includes a display screen, a processor, a direction sensor, a VR and a controller connecting line, a battery, a lens and an ultra wide band (UWB) positioning module. The UWB positioning module comprises the antenna, the ultra-wideband (UWB) transceiver and the high accuracy clock. The basic VR runtime includes an image processing unit, a positioning engine and an image transmission unit. According to the invention, the problem of dizziness caused by the uncertain positioning of a VR device and the long-term use of the device can be well addressed.

The invention provides a clock synchronization method and an apparatus in a transmission system. The method comprises the addition of carry values generated by the decimal portion of a system station clock period in t clock periods is calculated, wherein t is the total delay of a clock correction; a correction delay compensation value is calculated through t, the addition of the carry values and the integer portion of the system station clock period and the correction delay compensation value is used to carry out a synchronization correction towards a system subordinated clock. According to the invention, the problem in the prior art that the precision of system clock synchronization is low is solved and the clock synchronization precision of the system is increased.

The invention provides an ultra-wideband indoor positioning method, which mainly solves the problems of low precision, limited user quantity, great time synchronous errors and the like of the existing ultra-wideband indoor positioning system. The method comprises the steps of firstly, building an indoor navigation coordinate system, and arranging a base station; secondly, sending a positioning signal by the base station according to a system signal communication mechanism, so that positioning equipment held by a user only passively receives a distance measuring signal from the base station; then, realizing clock synchronization on an algorithm by using a clock deviation compensation algorithm of a Kalman filtering algorithm; finally, solving the user coordinate by a Taylor iterative algorithm. The ultra-wideband indoor positioning method has the advantages that the goal of simultaneously realizing indoor three-dimensional accurate positioning of infinite positioning equipment can be achieved; an additional hardware network is not needed for realizing clock synchronization; the positioning equipment only receives a positioning signal but does not send the signal; the stable swinging can be realized between a sight distance scene and a non-sight distance scene.

The invention discloses a clock synchronization method and a device, wherein the method and the device are applied to a micromicro base station (HeNB). The method and the device comprise that a standard base station is selected from adjacent base stations, a clock of the standard base station serves as a standard clock, a system clock is adjusted according to the standard clock; and clock precision level of the adjacent base stations are obtained, the signal strength and the path delay of time of the adjacent base stations are measured, weighing calculation is conducted on the path delay of time according to the signal strength and the clock precision levels of the adjacent base stations, and the system clock is adjusted according to the result of the weighing calculation. Due to the fact that two aspects of coarse adjustment and fine adjustment are conducted on the system clock, synchronization precision of the clocks of the micromicro base station is improved, descending and ascending interference between two adjacent micromicro base stations and between the micromicro base station and a macro station in the prior art is reduced, and accumulation of errors in the process of synchronization is reduced.

The invention relates to a method and a system for improving the positional accuracy of a Beidou navigation system by using photon pairs with a quantum entanglement feature. The method includes following steps: 1), producing the photon pairs with the quantum entanglement feature; 2), respectively sending the photon pairs with the quantum entanglement feature produced in step 1) to a first clock and a second clock in need of clock synchronization and recording the time from photons to the first clock and the second clock; 3), enabling two photons to pass through a beam splitter, and acquiring the time from the photons to the beam splitter; 4), acquiring a timing difference of the first clock and the second clock; and 5), adjusting the timing difference of one of the clocks according to the acquired timing difference of the two clocks so as synchronizing the two clocks. By the aid of the method and the system, the positional accuracy of the Beidou navigation system is evidently improved.

A clock synchronization method, a mobile network system, a network controller and a network switch are provided. The method computes a round-trip delay ratio between the network controller and the network switch according to a first delay, of which the network controller transmits a packet to the network switch, and a second delay, of which the network switch transmits another packet to the network controller. The method also locks a first clock based on a time-transfer protocol with the round-trip delay ratio, wherein the first clock is synchronized with a master clock of the network controller. The method further sets the first clock being locked as a runtime clock of the network switch.

The invention discloses a high-precision clock synchronization method and system for communication equipment, and relates to the field of clock synchronization. The method comprises the following steps: a clock unit of communication equipment issues a transmission delay value to a service disk, and the transmission delay value is obtained according to a clock sending signal issued to the service disk by the clock unit and a clock phase difference of a clock signal uploaded to the clock unit by the service disk; And the service disk performs phase compensation on the clock sending signal according to the transmission delay value to form a clock signal which is basically consistent with the clock phase of the clock sending signal. According to the invention, after the clock signal is subjected to phase compensation by receiving the transmission time delay value, the compensated clock signal can be aligned with the output phase of the clock sending signal, so that the influence caused bythe transmission time delay of the clock signal in the prior art is eliminated, and the clock synchronization precision is greatly improved.

The invention discloses a clock synchronization device and method. The clock synchronization device comprises a DC (Direct Current) block, an amplifier, a GPS (Global Positioning System) receiving module, a local clock reference module, a frequency dividing module, a time difference measuring module, a data processing module and an analog-digital converting module, wherein the DC block is used for outputting GPS signals from a parasitic antenna to the amplifier and cutting off a current fed back by the amplifier; the amplifier is used for amplifying the GPS signals and outputting the GPS signals to the GPS receiving module; GPS second pulse signals are obtained according to the GPS signals, and outputted to the time difference measuring module; the local clock reference module is used for outputting local clock reference signals to the frequency dividing module and correcting the local clock reference signals according to an analog voltage sent by the analog-digital converting module; the frequency dividing module is used for dividing the local clock reference signals into the second pulse signals and outputting the second pulse signals to the time difference measuring module; the time difference measuring module is used for measuring the time difference between the local clock second pulse signals and the GPS second pulse signals, and sending the time difference to the data processing module; a frequency deviation is obtained according to the time difference and sent to the analog-digital converting module; the analog-digital converting module is used for converting the frequency deviation into an analog voltage and sending the analog voltage to the local clock reference module. According to the invention, the clock synchronization precision is improved.

The invention relates to the field of underwater acoustic communication, and specifically relates to a dynamic clock synchronization method for underwater acoustic communication based on acoustic link distance measurement and speed measurement. The dynamic clock synchronization method provided by the invention comprises the steps that: a communication node B interrupts according to pulses with a cycle T and generated by high-precision clock drive; a communication node A receives a synchronization configuration signal a' of the B node at a T2 moment; the B node receives a synchronization request signal b' sent by the A node at a T3 moment at a T4 moment; the A node receives a synchronization response signal c' sent by the B node at a T6 moment; and the B node calculates an obtained clock error (the expression is described in the specification), and the A node calculates the obtained clock error. According to the dynamic clock synchronization method provided by the invention, a relative movement speed between the nodes is estimated by a pulse pair cross covariance algorithm to compensate the condition of unequal two-way propagation delay caused by relative movements of the nodes and improve the clock synchronization precision of the nodes under movement conditions, and when the relative movement speed is 5 sections, the clock synchronization precision can be lower than 1 millisecond.

The invention provides a clock synchronization method and device. The clock synchronization method comprises the steps of distributing a node number for each node in a network and determining a clock reference node in the network based on the node number of each node; carrying out time slot number correction for rest nodes in the network based on the time slot number information of the clock reference node so as to finish synchronization of the time slots of the nodes in the network; carrying out clock synchronization for the rest nodes in the network based on a round-trip delay correction mechanism and the clock counter information of the clock reference node so as to finish synchronization of clocks of the nodes in the network; and obtaining a timed correction time pre-set for the nodes and correcting the clock counter of each node periodically based on the timed correction time. The clock synchronization method reduces synchronization error caused by broadcasting delay and processing delay, corrects the difference of the clock frequencies inside each node, reduces expense of the network clock synchronization, enables the network to be in a synchronous state rapidly, improves the clock synchronization precision and keeps a relatively steady synchronous state.

The invention relates to a precise clock synchronization implementation method based on the PTPd2 protocol, belonging to the field of communication technology and computer networks. The invention realizes precise clock synchronization through an interactive communication message of master and slave clock devices, and the PTPd2 protocol can obtain an precise timestamp of the message arriving at thenetwork driver layer of the master and slave clock devices; compared with the timestamp obtained by the NTP protocol at the application layer, the interference of the protocol stack can be effectively avoided; at the same time, by capturing the time of the message reaching the MAC layer of the master and slave clock devices, and compensating for the delay and jitter generated by transmitting themessage from the network driver layer to the MAC layer in the master and slave clock devices, the clock synchronization precision can be improved. Tests show that when the master clock device and slave clock device are directly connected through a network cable, the parameters are reasonably set and the boundary time is compensated, the clock synchronization precision can reach 19[Mu]s; the universality is good; and the precise clock synchronization implementation method based on the PTPd2 protocol is easy to implement.

Embodiments of the invention disclose a clock synchronization method and device. The method and the device are applied to a network fusing radio over fiber RoF and a passive optical network PON. The method comprises the following steps that a hybrid optical line terminal OLT sends an obtained analog atomic clock synchronization signal to a network module through an RoF link, and the network module extracts the analog atomic clock synchronization signal; and the network module computes clock adjustment information and adjusts a clock of the network module through moment information recorded by the network module. According to the method and the device, in the RoF technology-based clock synchronization method, the RoF link is utilized for transmitting a precise analog atomic clock synchronization signal obtained by the hybrid OLT and the network module extracts the analog atomic clock synchronization signal, so that a problem of distortion after digitization of the clock synchronization signal can be effectively avoided, the clock synchronization precision of the network module at the access side is improved and the precise network clock synchronization is realized.

The invention relates to a remote optical fibre synchronous system for a radio astronomical array and a method thereof. The remote optical fibre synchronous system comprises a local phase-locked control module and a clock purification module, wherein the local phase-locked control module is arranged in a local node; the clock purification module is arranged in a remote node; the remote node and the local node are connected through an optical fibre; the local node inputs a local reference clock and a local optical fibre receiving clock received from the clock purification module into the local phase-locked control module; the local reference clock is controlled to perform phase adjustment through PID, such that a local optical fibre sending clock is obtained; and thus, optical fibre temperature drift compensation is realized. According to the invention, the optical fibre temperature drift compensation is carried out in a digital manner; the remote optical fibre synchronous system has high clock synchronous precision; the clock synchronous precision is up to the pico-second level; the remote optical fibre synchronous system is high in environment adaptive capability and low in cost; the clock information is transmitted in the digital manner; the remote optical fibre synchronous system is high in anti-interference capability and long in transmission distance; transmission of a sampling clock, sampling data and a system control command can be realized only through one optical fibre channel; therefore, high-degree system integration is realized; and the optical fibre wiring complexity is reduced.

The invention discloses a clock servo method for correcting an IEEE (Institute of Electrical and Electronic Engineers) 1588 protocol by utilizing an adaptive filter, which is used for solving the problem of poor synchronization precision of clock synchronization by utilizing a pure software mode in a wireless ad hoc network. According to the method, time delay and offset calculated by a system areprocessed by a self-adaptive filter, a filtering output result is fed back to the system, and a closed-loop clock servo method is formed by combining a PID controller. The self-adaptive filter continuously adjusts the filter coefficient, so that the unique target can be achieved along with the fluctuation of the wireless environment: the time delay is minimized, and meanwhile, the convergence speed of the system can be accelerated to a certain extent. Therefore, the problems of instability and overlong delay in the wireless ad hoc network are solved under the condition of not increasing additional hardware.

The invention discloses a method for improving the clock synchronization precision. The method comprises the steps that whether or not an event message is monitored from a hardware interface of equipment is judged, if the event message is received, a first hardware timestamp is generated, and due to the fact that the delay of a physical layer for message transmission is very short, the precision of the hardware timestamp is very high; a second hardware timestamp generated for responding the event message by the main equipment is acquired, and the transmission delay between the main equipment and the slave equipment is calculated by means of the first hardware timestamp, the second hardware timestamp and the transmission time between the main equipment and the slave equipment, wherein it isobvious that the precision of the transmission delay calculated according to the timestamps with the high precision is also high; and the clock time of the slave equipment is adjusted according to the transmission delay, clock synchronization is completed, and the purpose of improving the clock synchronization precision is achieved. The invention further provides a device and equipment for improving the clock synchronization precision and a computer readable storage medium. The device, the equipment and the computer readable storage medium have the effect corresponding to that of the method.

The invention relates to a multifunctional quantum secret communication node structure based on time division-wavelength division multiplexing, belongs to the technical field of quantum secret communication, and particularly relates to a method for realizing a transceiving function of a quantum secret communication node through the time division multiplexing technology. For the quantum secret communication node based on a single photo scheme and a Faraday- Michelson interference ring (F-M) structure, the bidirectional transceiving function of the node is achieved as long as an optical circulator and time division control logic of the transceiving function are added to the node. The node structure can be applied to a trusty relay node, a super node and an authentication center node to improve the reliability and expansibility of a whole quantum secret communication network. Strict clock synchronization required by the quantum secret communication network is achieved through the wavelength division multiplexing technology, and the synchronous time delay adjustment range is reduced.

First, microcontroller of coordinator in short range radio communication network sends command of sending beacon frame to local wireless send receive chip (WSRC). After receiving the command, WSRC sends beacon frame to general device, and calculates time F1 spent from the time for sending command to the time of sending synchronous start byte completely by WSRC. After receiving synchronous start byte in beacon frame, WSRC of general device sends jump signal from low electrical level to high level to local microcontroller. After receiving the jump signal, the local microcontroller records current time F2 of local clock. After receiving whole beacon frame, the general device records current time F3 of local clock. Based on F1, F2 and F3, new current time of local clock is equal to F1+ (F3-F2). Advantages are: using little resource, low hardware cost of network node, and easy of maintenance.

The invention relates to the technical field of aviation measurement and control, and provides a data acquisition method and equipment for an airplane test hydraulic system of a passenger plane. The method comprises the steps that a clock synchronization network completes clock synchronization of a test terminal, a test server and a test management system; The test server issues a test configuration file through the gigabit Ethernet; The test sensor, the airborne bus and the system sensor collect parameters of a hydraulic system at the same time, and distribute collected signals to the signalconditioner through the signal transfer box, the straight-through signal distributor and the isolation signal distributor to complete signal conditioning. The conditioning signal and the straight-through signal are transmitted to the test terminal and are uniformly converted into test data; the non-real-time data in the test data is transmitted through the gigabit Ethernet; And real-time data in the test data is transmitted through the optical fiber reflection memory network. The embodiment of the invention has the characteristics of distributed acquisition, easiness in expansion, high real-time performance and high clock synchronization precision, and is suitable for data acquisition of a large-passenger aircraft iron bird test hydraulic system.

The invention discloses a time-triggered Ethernet clock synchronization method based on crystal oscillator frequency digital compensation, relates to the technical field of clock synchronization of adistributed communication network, and solves the problem of frequency deviation calibration in a clock synchronization process. According to the method, a clock trigger Ethernet model is establishedbased on an SAE AS6802 protocol, and a clock synchronization process is simulated through network calculation. A VerilogHDL tool is adopted to design crystal oscillator frequency-temperature characteristic curve lookup table and improved local clock module comprising crystal oscillator frequency digital compensation module, and is applied to a network node hardware model. The local clock module isimproved to occupy less hardware cost, the digital frequency deviation of the crystal oscillator is compensated, the network clock synchronization precision is effectively improved, and the method can be widely applied to an aerospace electronic system and a vehicle-mounted control system.

The embodiment of the invention discloses a clock synchronization method, system and equipment based on a PTP, and relates to the field of wireless communication. The clock synchronization method, system and equipment are used for improving clock synchronization precision of slave equipment. According to the clock synchronization method, system and equipment, after the slave equipment receives synchronization messages sent by master equipment, the time point t2 when the synchronization messages reach the slave equipment is recorded, and a time point t1 when the master equipment carried in the synchronization messages sends synchronization messages is read and recorded; the slave equipment generates delay request messages, enables a time point t3 when the delay request messages are sent to be carried into the delay request messages, and sends the delay request messages to the master equipment; delay response messages sent by the master equipment are received, the time point t3 in the delay response messages and a time point t4 when the delay request messages reach the master equipment are read, and a local clock is regulated according to the time point t1, the time point t2, the time point t3 and the time point t4 to enable the local clock to be synchronized with a clock of the master equipment. By the adoption of the clock synchronization method, system and equipment, clock synchronization precision of the slave equipment can be improved.

The invention relates to a clock delay compensation device which comprises a first trigger circuit, a delay compensation circuit, a second trigger circuit, a crystal oscillator and a time output circuit. The crystal oscillator is connected with the time output circuit and the delay compensation circuit respectively; the delay compensation circuit is also connected with the first trigger circuit and the second trigger circuit respectively; the second trigger circuit is also connected with the time output circuit; and the crystal oscillator is used for providing stable clock frequency for the time output circuit and the delay compensation circuit. Moreover, the invention also provides a clock delay compensation synchronization method for realizing clock synchronization by using the clock delay compensation device. By means of the technical scheme, the the clock synchronization precision cane be improved and the invention is applicable to occasions with relatively high requirements on clock accuracy such as nuclear power, high-speed rails, stations and airports.

Embodiments of the invention disclose a clock synchronization method and device. The method and the device are applied to a network fusing radio over fiber RoF and a passive optical network PON. The method comprises the following steps that a hybrid optical line terminal OLT sends an obtained analog atomic clock synchronization signal to a network module through an RoF link, and the network module extracts the analog atomic clock synchronization signal; and the network module computes clock adjustment information and adjusts a clock of the network module through moment information recorded by the network module. According to the method and the device, in the RoF technology-based clock synchronization method, the RoF link is utilized for transmitting a precise analog atomic clock synchronization signal obtained by the hybrid OLT and the network module extracts the analog atomic clock synchronization signal, so that a problem of distortion after digitization of the clock synchronization signal can be effectively avoided, the clock synchronization precision of the network module at the access side is improved and the precise network clock synchronization is realized.

The invention provides a clock synchronization method and device. The clock synchronization method comprises the steps of distributing a node number for each node in a network and determining a clock reference node in the network based on the node number of each node; carrying out time slot number correction for rest nodes in the network based on the time slot number information of the clock reference node so as to finish synchronization of the time slots of the nodes in the network; carrying out clock synchronization for the rest nodes in the network based on a round-trip delay correction mechanism and the clock counter information of the clock reference node so as to finish synchronization of clocks of the nodes in the network; and obtaining a timed correction time pre-set for the nodes and correcting the clock counter of each node periodically based on the timed correction time. The clock synchronization method reduces synchronization error caused by broadcasting delay and processing delay, corrects the difference of the clock frequencies inside each node, reduces expense of the network clock synchronization, enables the network to be in a synchronous state rapidly, improves the clock synchronization precision and keeps a relatively steady synchronous state.

The invention discloses a time stamp jitter compensation method and system, and relates to the field of time synchronization. The method is applicable to messages with a time stamp, and the steps of the method include: the receiving end calculates the time interval between sending the current message and the last message, and the receiving time interval between the current message and the last message, Compensate the timestamp of this packet. The present invention compensates and corrects the time stamp of this message through the sending time interval and receiving time interval of two adjacent messages; that is, avoids delay jitter and time synchronization jitter through the sending time interval and receiving time interval, It not only significantly improves the clock synchronization accuracy, but can effectively reduce the impact of link delay jitter on synchronization stability; it does not need to consider the position of the timestamp record and the clock frequency, that is, it does not need to improve the hardware.

The present invention relates to the technical field of clock synchronization path query, and provides a clock synchronization path query method and system based on a ring network. The method includes: S1: for each port of a slave clock device, preset the serial number of the device port; S2: master clock device Send the clock synchronization path management message from all ports along the message forwarding path, and return to the master clock device after a cycle of transmission in the ring network; S3: The slave clock device receives the clock synchronization path management message from each port, and transfers the clock The forwarding port serial number in the synchronization path management message is compared with the device port serial number of the receiving port of the slave clock device. If the forwarding port serial number is the previous serial number of the device port serial number, the synchronization path has not changed, and the current packet forwarding path is used as Clock synchronization path from the clock device. The slave clock device receives periodic synchronization packets from the clock synchronization path to perform periodic clock synchronization without recalculating the line delay.