35results about How to "High precision time synchronization" patented technology

The invention discloses a time synchronization method of a master-slave structure multi-node network. Two clock synchronization mechanisms of a response type mechanism and a broadcast type mechanism are designed aiming at the condition that nodes of the network are physically connected through wires, and the communication between the nodes is performed through RS485, RS422, RS232, CAN bus modes. Accurate sending and receiving times of each message can be obtained through FPGA clock sampling. The transmission average delay and the master-slave clock offset are calculated through a response type synchronization mode, and the time precision is compensated and the time synchronization with the nanosecond grade high precision is reached. The time synchronization with the higher precision can be reached when the channel transmission time delay is ignored through a broadcast type synchronization mode.

The invention relates to a symmetrical noncoherent distance measurement/time synchronism system of a cluster link two-way asynchronous communication channel, belonging to the autonomous technical field of aviation data links, radio navigation and aircrafts. By the invention, a symmetrical noncoherent distance measurement/time synchronism method and a system framework can be realized on a DSP (Digital Signal Processor) of a circuit board and an FPGA (Field Programmable Gate Array). Based on the two-way asynchronous communication link between cluster link member nodes, the noncoherent distance measurement/time synchronism system provides a noncoherent spread spectrum distance measurement principle of a two-way asynchronous communication frame under a comprehensive channel system, constructs a noncoherent spread spectrum distance measurement algorithm structure of the air fleet link two-way asynchronous communication frame in a uniform form by adopting a communication frame based on CCSDS Proximity-1 version-3 and provides two algorithms of base line measurement and time synchronism measurement control: an interprocessor time synchronism recursive algorithm and a Doppler integral compensation algorithm. The invention overcomes the defects of the traditional coherent transferring distance measurement and the two-way synchronous noncoherent distance measurement and provides a distance measurement scheme, in which both parts of the two-way asynchronous communication distance measurement can equally acquire a measurement result.

A time synchronization system comprises a GPS (Global Positioning System) receiver for receiving a time signal from a Global Positioning System (GPS), and outputting a UTC (Universal Time Coordinated) synchronization reference signal synchronizing with UTC and a UTC synchronization absolute time signal, and a time signal distributor for generating a reference time signal synchronizing with UTC from the synchronization reference signal and the absolute time signal, and transmits this reference time signal in distribution to a plurality of distributed control oriented terminal devices. The time synchronization between the plurality of distributed control oriented terminal devices can be thereby taken.

A method for synchronizing symbol timing and frequency of symmetric-identical (SI) Orthogonal Frequency Division Multiplexed signals (OFDM) wherein an SI preamble is used for calculation of the symbol timing and frequency synchronism offset of the OFDM signals out of the samples of the received signals is provided. The SI preamble includes a first sample group and a second sample group, being alternately arrayed several times, in which the first sample group includes a designated number of samples that are arrayed in order of arrival, while the second sample group includes the same number of samples with the first sample group, but in inverse order of arrival. Because distinctive correlation coefficients of the identical samples are very distinctive from each other, it is possible to estimate a starting point of the OFDM symbol more precisely. Using the SI preamble, both symbol synchronism and a fine frequency offset and a coarse frequency offset can be estimated. Moreover, the transmission efficiency and the overall capacity of the OFDM system are greatly improved.

The invention discloses a time synchronization method for multi-subsystem equipment and a subsystem. The method comprises that: correspondence between a clock mode of precision time protocol (PTP) networking to which the equipment is to be added and the clock modes of the subsystems is configured on the multi-subsystem equipment to be added to the PTP networking; PTP initialization parameters are configured on internal ports of the multi-subsystem equipment; each subsystem of the equipment receives the announcement that the equipment is to be added to the PTP networking, determines own clock modes according to the clock mode, carried in the announcement, of the PTP networking to which the equipment is to be added, and simultaneously performs PTP initialization according to the PTP initialization parameters configured on own internal ports, and each internal port starts running PTP functions after the initialization is finished; and each subsystem of the equipment performs PTP message interaction with other equipment in the PTP networking by the ports running the PTP functions, and performs time synchronization according to interacted PTP messages. By the method, high-precision time synchronization can be realized between all the subsystems and an external clock when the multi-subsystem equipment is added to the PTP networking.

The invention belongs to the time synchronization technical field and discloses a distributed network time synchronization method. The method includes following steps that: the difference of the clock of a center node and the clock of terminal nodes is determined; after receiving time synchronization request signals sent by different terminal nodes through different carrier frequencies, the center node captures, tracks and demodulates the request signals by using a local spread spectrum sequence database so as to obtain terminal node serial numbers, request sign information and terminal node clock information contained in the request signals, and center node clock information is compared with the local clock of the center node, time difference is measured; and offset correction is performed on the local clock of the terminal nodes according to the difference of the clock of the center node and the clock of the terminal nodes. Through synchronization, accuracy can reach a level of several hundreds of nanoseconds or even a level of dozens of nanoseconds.

The invention discloses a time synchronization method and a time synchronization device of an optical transport network asynchronous network. When a site in an optical transport network receives a time message transmitted by other sites, a first line card in the site recovers clock frequencies of one or a plurality of clock optical path data units(ODUm), wherein m is positive integers which are less than or equal to k, k is an optical path data unit order, and k is equal to 1, 2, 3 and 4, the service of the first line card uses a local clock to be converted to a data frame format of a back plate, the clock ODUm is sent to a second line card in the site through a cross board; the second line card uses the local clock to receive data frames of the back plate and restore the clock frequency of the clock ODUm, and the local clock or a service restoring clock of an optical path transmitting unit (OTUn) optical port is used to send the whole OTUn, wherein n is the order of the optical path transmitting unit. By adopting the time synchronization method and the time synchronization device of the optical transport network asynchronous network disclosed by the invention, the high-precision time synchronization can be supported under the condition that the present optical transport network OTN is asynchronous.

The present invention provides a repeater one-station-emitting and multiple-station-receiving secondary planet track detecting method which relates to deep-space tracking technique. Wherein only one ground track detecting station capable of receiving and emitting signals are provided, and other ground track detecting stations are receiving stations. In wartime, emitting station can change according to needs, even emitting in movement without losing precision, to ensure the concealment of whole system, avoid the track detecting station is discovered by enemy efficiently, and enhance the anti-destruction capability and anti-jamming capability of whole system.

The invention relates to a time synchronization method based on a troposcatter channel. The time synchronization method based on a troposcatter channel transmits a time comparison signal to the troposcatter channel, and includes the following steps: establishing a scatter link; sending a time comparison signal generated by a master station atomic clock to a pulse gate, obtaining a video signal bymultiplying a pulse signal which is obtained through processing by the pulse gate by a sine wave, and sending out the obtained video signal through a signal transmitter; sending a time comparison signal to the time interval counter from a slave station atomic clock, and starting timing by the time interval counter; after a signal receiver receives the time comparison signal of the master station,sending the time comparison signal to the time interval counter through a low noise amplifier, a band pass filter, an automatic gain control module and a broadband matching filter, and stopping timingand sending the counted value to a time synchronization data processing unit after the time interval counter receives the time comparison signal of the master station; and calculating the clock difference between the master station and the slave station by the time synchronization data processing unit, determining whether the two station is synchronous in time, and if not, then performing calibration. The time synchronization method based on a troposcatter channel has the characteristics of being autonomous, rapid and over-the-horizon.

The embodiment of the invention provides a time synchronization method, a service single board and network equipment. The method comprises the steps that after clock board time synchronization betweenservice single boards, the service single boards obtain CPU time and clock board time of the service single boards according to a preset period and record the CPU time and the clock board time; whenCPU time synchronization between the service single boards is executed, the service single boards obtain current CPU time of the service single boards, and the synchronization time of the CPU is calculated according to the current CPU time and the latest recorded CPU time and clock board time; and the CPU time in the service single board is adjusted to the synchronization time. According to the method, the clock board time between the service single boards needing to realize CPU high-precision time synchronization is synchronized through a high-precision time synchronization protocol, and thenthe CPU time in each service single board is adjusted to the corresponding synchronization time, so that the high-precision time synchronization between the CPUs of the service single boards can be realized.

A method for analyzing technical processes is disclosed, which is characterized in that measuring data of the technical process is generated by at least one decentralized measuring unit, image data associated with a mechanical course of the technical process is produced by at least one decentralized image detection unit, the measuring data stored in the at least one decentralized measuring unit and the image data stored in the at least one image detection unit is provided with a time stamp available to all systems, the measuring and image data are transmitted to a central detection unit where said data is displayed and/or processed in a time-synchronous manner using the time stamp function. Since time stamping is carried out directly in situ, i.e. decentrally in the respective measuring and image detection units, data transmission time required to transmit data to the central detection unit is not critical, so that a time-synchronized display and/or further processing of the measuring and image data can be carried out in the central detection unit with a high degree of accuracy.

The present invention achieves, using simple circuits, timing synchronization among ECUs of an electronic control device which is configured from a driver ECU, a sensor ECU, and an integrated ECU which are connected over a network. This electronic control device is provided with a driver ECU for driving various loads for vehicular control, a sensor ECU for sampling various sensor signals, and an integrated ECU which is connected to the driver ECU and sensor ECU over a network and calculates command values to the various loads in accordance with various sensor data, the electronic control device being characterized in that the driver ECU has timer D for generating internal timing, the sensor ECU has timer S for generating internal timing, and the integrated ECU has timer M serving as a reference for timer D and timer S.

The invention provides a time synchronization method and device, a medium and a program product, and the method comprises the steps: obtaining first ranging information sent by a satellite navigation system and auxiliary information sent by an auxiliary satellite system; the auxiliary information comprises precision orbit data and precision clock error data of the navigation satellite and the auxiliary satellite, second ranging information measured by the auxiliary satellite and first time difference uploaded to the auxiliary satellite by the data center; determining a second time difference between the local time and the navigation time of the ground terminal by using a preset positioning model according to the first distance measurement information and the auxiliary information when positioning calculation is performed on the ground terminal; and correcting the local time according to the first time difference and the second time difference, so that the local time is synchronized with the reference time. The auxiliary satellite system covers the globe, so that the technical problem that time transmission must be performed by depending on a ground communication network in the prior art is solved.