152results about How to "Improve time synchronization accuracy" patented technology

The invention provides a hierarchical structure based wireless sensor network time synchronization method. According to the hierarchical structure based wireless sensor network time synchronization method, gateway nodes and aggregation nodes are distributed in a monitoring site in advance and sensor nodes are carried by operators; the gateway nodes send hierarchy establishment broadcast data packages with time stamps; the aggregation nodes and the sensor nodes within the communication distance range extract hierarchy information after receiving the data packages, hierarchies of the aggregation nodes and the sensor nodes are changed by adding one to the current hierarchies, and local clocks are modified according to the time stamps; the gateway nodes are served as global time after network hierarchies are built, the timed polling sends time synchronization data packages to aggregation sub-nodes and the aggregation nodes synchronize the local clock time and the global time through the time synchronization algorithm; the sensor nodes perform time synchronization on the local clocks by intercepting time synchronization mutual data package information. The hierarchical structure based wireless sensor network time synchronization method achieves high accuracy time synchronization and improves the wireless sensor network channel utilization rate and the network life cycle.

An information processor capable of ensuring time synchronization accuracy, ensuring EtherCAT command consistency, and easily developing the software based on a 2-port configuration even when a communication path error occurs includes: an arithmetic section; at least two communication sections each including a transmission section and a reception section; and a redundant communication control section that controls a communication path between the arithmetic section and the communication section. The redundant communication control section includes: a communication path state determination section that determines a network path state; and a redundant path switching section that switches connection between the arithmetic section and at least two communication sections. The network provides a logical ring topology for a packet communication path. The redundant path switching section functions based on the communication path state determined by the communication path state determination section and changes a connection path between the communication sections and a communication path between the communication section and the arithmetic section.

Provided are a time synchronization method allowing a fixed time delay and a bridge that is interposed between a master and a slave, according to the method. In the bridge, a predetermined time after the synchronization packet is set as an output time of the synchronization packet and the synchronization packet is output at the output time. Accordingly, it is possible to delay synchronization packets in the bridge for the same time, thereby increasing the time synchronization precision.

The invention discloses a virtual machine time synchronization method and device. The method comprises the steps that virtual PTP equipment and an interface function are added to a virtual machine; the virtual PTP equipment is used for reading and transmitting back the time of a physical host through the interface function; a time synchronization virtual machine of the physical host is used. According to the method and device, different virtual machines or different types of virtual machines can be subjected to time synchronization, and higher time synchronization accuracy can be achieved without needing hardware supporting.

The invention relates to a power distribution network time synchronization system and method, and particularly relates to an intelligent power distribution network time synchronization system and method based on a PTN+EPON communication system. The intelligent power distribution network time synchronization system comprises an accurate clock source device. A primary clock port of the accurate clock source device is connected with a secondary clock port of a local end PTN device via an IEC61588 protocol. The primary clock port of the local end PTN device is cascaded with PTN devices in multiple transformer stations so that an annular structure is formed. The primary clock port of each PTN device in each transformer station is connected with a router which is connected with the secondary clock port of an OLT device via a switch. The OLT device is connected with an ONU device via an optical fiber. The primary clock port of the ONU device is connected with a power distribution terminal. According to the intelligent power distribution network time synchronization system, only a GPS is used as a clock source. An IEC61588 technology is applied, accurate time is transmitted step by step via a communication system so that time synchronization of the whole intelligent power distribution network is realized. Time accuracy is superior to 1 microsecond theoretically so that dependency on the GPS is low, and a requirement of the intelligent power distribution network towards time synchronization can be met. Therefore, the intelligent power distribution network time synchronization system is simple in structure and high in practicality.

The invention relates to a clock synchronization method in an FC-AE-1553 network. The method comprises the following steps: a main clock of the FC-AE-1553 network receives time information, and accomplishes the clock synchronization of the main clock according to the time information, wherein the main clock subjected to the clock synchronization is marked as BMC; and other nodes in the FC-AE-1553 network performs the clock synchronization based on a time synchronization frame according to the BMC. The clock synchronization comprises frequency synchronization and time synchronization, estimation and correction of own frequency offset are realized by the frequency synchronization, and the compensation of delay time is realized by the time synchronization. The clock synchronization mode in the FC-AE-1553 network further comprises a gradual synchronization mode, a boundary clock/transparent clock switch synchronization mode and a transparent clock switch mode. The design of the clock synchronization mode in the FC-AE-1553 network solves the problems that the time synchronization precision is low and that a special hardware device needs to be paved, resulting in a high investment cost in the prior art, and the time synchronization demands of the majority of the new generation of loads can be satisfied.

The invention provides a timestamp generation method, a device and a system. The timestamp generation method comprises the following steps: a data packet processing unit receives a data packet transmitted by a physical layer receiving/transmitting unit or a higher layer; whether the data packet is a precise time synchronization protocol PTP packet is identified; and if the data packet is a precise time synchronization protocol PTP packet, a precise timestamp is generated according to physical layer delay provided by a physical layer delay acquisition unit and non-physical layer delay provided by a non-physical layer delay acquisition unit, and the timestamp field of the data packet is rewritten. The precision of timestamp is effectively improved, and the precision of time synchronization of the whole communication network is improved.

The invention discloses a base station positioning method based on a high-precision time synchronization network, and belongs to the field of navigation positioning. The method comprises the following steps: acquiring absolute time or relative time difference of transmission of radio waves between a terminal to be positioned and at least three base stations; obtaining spatial coordinate information of the base station in a preset coordinate; calculating a relative distance or a relative distance difference between the terminal to be positioned and the base station according to the absolute time or the relative time difference; according to the relative distance or the relative distance difference and the space coordinate information and a preset strategy, obtaining position information of a to-be-positioned terminal; and constructing an optical fiber tree topology structure network between the base stations. According to the method, the time synchronization error of a slave clock and a master clock is adjusted; the time synchronization of the slave clock and the master clock is realized, the time synchronization precision of the base station is improved, the subnanosecond level is reached, when the distance difference between the base station and the to-be-positioned mobile terminal is obtained through positioning calculation, the time value measurement is more accurate, the centimeter-level positioning error can be realized, and the positioning precision is greatly improved.

The invention discloses a precise timing system and method and a timing service system. The precise timing system comprises a satellite-based enhancement system, the timing service system and a user terminal. The satellite-based enhancement system sends wide area enhancement information to the timing service system. The timing service system receives GNSS observation data from satellites, the widearea enhancement information and reference time from a timing service center, processes the observation data and the wide area enhancement information to obtain system time of each satellite, and obtains a real-time system time difference of the system time of each satellite relative to the reference time on the basis of the system time of each satellite and the reference time. The user terminalreceives the GNSS observation data from the satellites, the real-time system time difference of the timing service system and the reference time at least, processes the GNSS observation data to obtainlocal time of a user and system time of a navigation system, obtains a difference between the user local time and the reference time according to the real-time system time difference and the difference between the user local time and the navigation system, and the user local time is corrected to the reference time according to the obtained difference between the user local time and the referencetime.

The invention provides an image time hack information generating system of a space camera, and relates to the space camera. The problems that in an existing method, the errors of time synchronization of the camera are large and vary greatly along with the operation time sequence of a camera controller, and high precision time scales and platform time scales can not be used for conducting time hack are solved. The image time hack information generating system of the space camera is composed of an asynchronous serial communication interface chip, a GPS pulse per second level switch chip, a frame/line synchronization level switch chip, a crystal oscillator and an image time hack information generation FPGA. A state machine is used for processing high-precision time scales and platform time scales, image time hack information data are generated in a pure hardware time sequence circuit mode, and it is guaranteed that the corresponding relation of line numbers and time codes in the image time hack information is accurate and reliable through latching twice. The image time hack information generating system of the space camera can achieve higher camera time synchronization precision, when a GPS and related receiving equipment break down, self-time keeping can be achieved, the platform time scales can be used for conducting time hack, and it is guaranteed that the generated image time hack information can still maintain certain precision.

The application provides a clock synchronization method and device. The clock synchronization method includes the following steps that: synchronization end equipment generates a timestamp according tothe time of receiving and sending a periodic code block on a predetermined channel; the synchronization end equipment performs time information message receiving and transmission with synchronized end equipment, and determines a time deviation with the synchronized end equipment according to the timestamp of the periodic code block matching the received and transmitted time information messages;and the synchronization end equipment adjusts a system clock according to the determined time deviation.

The invention discloses a bionic eye multichannel IMU and camera hardware time synchronization method and device. The method comprises the steps as follows: IMU setting is performed, the output frequency of IMUs is used as a period reference of hardware time synchronization and alignment, and pulse signals are synchronously output when the IMUs output data; camera setting is performed, the relatedattributes and fixed exposure duration of image acquisition of the cameras are set, the cameras are enabled to perform image acquisition after receiving external trigger pulses, and trigger pulse signals for the cameras are generated by using output pulse signals from the IMUs; and a hardware synchronization unit performs frequency division according to a fixed frequency when capturing output pulse signals from the IMUs, and generates trigger pulse signals to synchronously trigger the cameras in all channels. Accurate hardware synchronization and alignment are realized, and depth informationof an environment sensed by a bionic eye system and real-time three-dimensional pose information during movement of the bionic eye system can be recovered more quickly and accurately. The method and the device are worthy of popularization.

The invention belongs to the technical field of satellite navigation, and in particular relates to an apparatus for time synchronizing based on multi-satellite common view and a [alpha]-[beta] filtering and a method thereof. The apparatus includes connected time synchronous modules which are mounted inside two pseudo satellites, wherein the time synchronous module includes: a multi-channel receiver module, a communication module, an information processing and clock correcting module. The method includes: through collection data of the two pseudo satellites, obtaining the position of the satellite tested and pseudo ranges with respect to the pseudo satellites A and B, obtaining an elevation angle of the satellite through calculation, and conducting weighting and averaging with the sine value of the elevation angle as the weight, conducting the [alpha]-[beta] filtering in combination with the mathematical model for clock error, further correcting clock errors, eventually obtaining a more accurate clock error estimation value, correcting the clock error of the pseudo satellite which needs synchronization based on the clock error estimation value, and at last achieving the time synchronization between the two pseudo satellites. The embodiments of the invention can eliminate random error in observed quantity, increase precision of time synchronization, and have a stronger ability than single channel common-view time synchronization method in terms of anti-interference.

The invention discloses a time synchronization method of an open loop network for a TDMA (Time Division Multiple Address) node based on a kalman filter. The time synchronization method comprises the following steps that: an NTR (Network Time Reference) node broadcasts a beacon message; after a non-NTR node receives a broadcast beacon, a time slot number of transmitting an inquiry message by the non-NTR node is determined and a local clock is updated; the non-NTR node and the NRT node interact an RTT-I (Round-Trip Time) message and an RTT-R message, and a measurement time is computed; the non-NTR node corrects the local clock by utilizing a synchronous filter, and checks a local prediction time through the measurement time obtained through RTT inquiry so as to correct, and a phase and a temperature excursion frequency at non-NTR time are estimated through iteration. According to the iterative estimation method, precise time synchronization can be implemented by a synchronous terminal. A synchronous filter can keep synchronization continuously within a longer time without updating of the measurement time. The time synchronization method solves the problem of time synchronization of the TDMA node under a high-dynamic quick travel environment, and has the advantages of capability of improving network synchronization precision, simple protocol processing, small amount of occupied resources and low equipment requirement.

The invention relates to the industrial wireless network technology, in particular to a factory automation wireless network time synchronizing method based on time division multiple address (TDMA). The factory automation wireless network time synchronizing method is based on the institute of electrical and electronic engineers (IEEE) 802.11 standard and the TDMA mechanism, by adopting a hardware timestamp printing method and calculating the timestamp values of a receiving side and a dispatching side, time deviation caused by processing delay of a protocol stack, delay from a physical layer interface to a wireless media interface (antenna) and delay of information transmission in the air can be eliminated, and accurate time synchronization of a factory automation wireless network can be achieved. On the basis that no additional expenses can be caused, the factory automation wireless network time synchronizing method remarkably improves the time synchronization accuracy of the factory automatic wireless network based on the IEEE 802.11 single-hop network, meets severe requirements on transmission speed, reliability, instantaneity and network scale of the factory automatic network and achieves the aims of being high in synchronizing accuracy, high in efficiency, low in expense, easy to achieve and the like.

The invention discloses a Doppler assisted underwater sensor network time sync method. A beacon node continuously broadcasts message data packets; a to-be-synced node continuously receives the messages broadcasted by the beacon node; the native time of the to-be-synced node is recorded each time when the messages are received; the relative speed between the to-be-synced node and the beacon node is calculated; the to-be-synced node calculates clock frequency deviation by employing collected data; after the to-be-synced node calculates the clock frequency deviation, a request message is sent to the beacon node; after the beacon node receives the request message sent by the to-be-synced node, a response message is sent to the to-be-synced node after a random period of time; when the to-be-synced node receives the response message sent by the beacon node, the native time is recorded; the relative speed between the to-be-synced node and the beacon node is calculated by employing a calculation method; and finally the final clock phase deviation is calculated through the collected data. According to the method, the negative effects of node movement on time sync can be reduced, and therefore, the time sync precision is improved.

The invention relates to a wireless sensor network time synchronization method, which comprises coarse timing and fine timing operation. Each node in the wireless sensor network is provided with an independent timing clock; a data communication ability is realized between nodes; a to-be-synchronized node B carries out coarse timing and fine timing operation on a reference node A at each T time to enable the time of the to-be-synchronized node B and the time of the reference node A to be consistent. Compared with the traditional wireless sensor network time synchronization method, the method of the invention can carry out time synchronization on the wireless sensor network node more accurately.

The invention discloses a synchronized method and device of encrypted messages between each other, and relates to the field of digital information transmission. The method includes steps of determining whether to stamp an indicating signage of time according to a message content before being encrypted, and generating a first sending time stamp t3 corresponding to a message sending time at the corresponding encrypted message while sending a message; generating a first receiving time stamp t2 corresponding to a message receiving time at the received message, and deciphering the received encrypted message while receiving the message; performing time synchronization by using the first sending time stamp t3, the first receiving time stamp t2 and a second receiving time stamp t4 of the corresponding encrypted message received by a master clock node and a second sending time stamp t1 of sending the message. The synchronized method and device of encrypted messages improves time synchronization accuracy of master and slave clock nodes on the premise of guaranteeing data network security.

The embedment of the invention provides a synchronous time updating method and a synchronous time updating device. The method comprises: when determining it is necessary to query the synchronous time information of a next-hop node of a current node, sending query broadcast to the neighboring nodes of the current node, wherein the broadcast at least carries the working period broadcast serial number, which is recorded in the current node, of the next-hop node; and receiving update data packets from the neighboring nodes of the current node, and updating the synchronous time information, which is recorded in a neighbor list of the current node, of the next-hop node according to the synchronous time information, which is carried by the update data packets, of the next-hop node of the currentnode.

The invention discloses an underground hybrid network time synchronization method based on a time sensitive network. According to the method, a multi-sink node clustering distributed time synchronization scheme is carried out aiming at the problems of poor time synchronization precision and high energy consumption of a wireless sensor network in a narrow and long area of an underground roadway anda communication difficulty environment. The method comprises the following steps: firstly, establishing a multi-sink node non-uniform clustering routing topological structure by an underground wireless sensor network; secondly, after layering, adopting an accurate clock synchronization algorithm in a convergence network, adopting an estimation algorithm based on Kalman filtering in a wireless main network, and adopting a one-way and two-way hybrid synchronization algorithm in a slave network. According to the method, the time synchronization precision and stability of the underground sensor network are improved, and the energy consumption of the wireless sensor nodes is reduced and balanced.

The invention discloses a time synchronizing method and a system thereof. The method comprises the steps of when data collecting equipment detects a fact that a receiving time window of a time synchronizing pulse signal is effective, receiving a time synchronizing pulse signal; generating a time synchronizing data packet based on the time synchronizing pulse signal and transmitting to data acquisition equipment; when the data acquisition equipment receives the time synchronizing data packet which is transmitted by the data collecting equipment in a wireless communication manner, recording a clock counting value; based on two adjacent clock counting value which are recorded, calculating a local time interval; subtracting a preset standard time interval from the local time interval for obtaining a time interval error; determining whether the time interval error is larger than an error threshold; if yes, adjusting a sampling parameter of the data acquisition equipment, and otherwise, preventing adjustment of the sampling parameter. The time synchronizing method and the system thereof greatly reduces time delay of the time synchronizing data packet and furthermore controls the time delay in a predictable range.

The invention discloses a time synchronizing method based on wireless communication and a system thereof, wherein the time synchronizing method comprises the steps of receiving a time synchronizing pulse signal transmitted from a global positioning system by data collecting equipment; transmitting preset time synchronizing information to data acquisition equipment by the data collecting equipment;when the data acquisition equipment monitors a first bit of the time synchronizing information, starting time synchronization; and receiving the time synchronizing information by the data acquisitionequipment. The time synchronizing method and the system thereof can improve time synchronizing precision.

The invention discloses a time synchronization method of a wireless sensor network. A main node firstly generates a synchronous beacon frame; then, a low-complexity encoding scheme is preset accordingto the hardware configuration condition of the sensor node chip; error correction coding of the synchronous beacon frame is completed; the encoded synchronization information is periodically broadcasted; and after receiving the data packet, the slave node firstly selects a corresponding software or hardware decoding method for rapid decoding according to a preset encoding scheme, then identifiesand verifies a decoded data frame, finally realizes time synchronization with the master node according to a flooding time synchronization protocol, and sends a user data packet. According to the invention, the problem of high packet error rate of transmission of the synchronous beacon frame in the wireless channel is solved; based on hardware resource characteristics and a coding and decoding method of sensor nodes in a wireless sensor network, a coding scheme with low complexity and high error correction capability is realized by adopting coding, reliable transmission of synchronization information is ensured, and improvement of time synchronization precision and prolongation of synchronization survival time are facilitated.