58results 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 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 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 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 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 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.