131results about How to "Reduce synchronization error" patented technology

The invention discloses a method for time synchronous transfer, which comprises the following steps: transmitting a synchronous pulse and transmitting time information of a main device by the main device; receiving the synchronous pulse and recording received time information of a slave device by the slave device; acquiring the transmission time delay of the synchronous pulse; determining the time deviation between the main device and the slave device by the slave device according to the transmitted time information of the main device, the received time information of the slave device and thetransmission time delay; and adjusting a local synchronous clock by the slave device according to the time deviation. The invention also discloses a system and a device for the time synchronous transfer. The method, the system and the device obtain the synchronous errors among devices and compensate the clock according to the synchronous errors so as to reduce the synchronous errors caused by thetransfer time delay of PPS and ensure that the synchronous errors of the cascade connection of a multilevel device are still lower than microsecond level.

The invention discloses a high-precision synchronous multi-channel image acquisition system and a method thereof. The system comprises a time source, a plurality of video acquisition units and a plurality of cameras. The method comprises six steps. According to the high-precision synchronous multi-channel image acquisition system and the method, synchronous time signal synchronization camera shooting is adopted for trigger signals, strict synchronization of shooting moments (exposure moments) of multi-channel cameras is achieved, the shooting moments are strictly synchronous with time of a time source, and the requirement for high-precision multi-channel synchronous image acquisition is met; timestamp information of trigger pulses is recorded, so that timestamps marked by images are the shooting moments, the timestamp marking precision is improved, follow-up information extraction and measurement analysis of multi-channel images are facilitated, and the good economic and social benefits are obtained.

The invention is a network-based multimedia synchronous teaching system in the field of network technique, comprising: audio/video collecting tool, electronic document collecting tool, synchronous teaching support platform, and synchronous courseware browsing tool, where the audio/video collecting tool takes charge of collecting and compressing audio/video signals in the schoolteaching field and transmitting the compressed audio/video signals to the synchronous teaching support platform; the electronic document collecting tool takes charge of real-time collecting on-screen schoolteaching data of a teacher and compresses them into web pictures and transmitting the web picture to the synchronous teaching support platform; the synchronous teaching support platform receives the compressed and packet audio/video schoolteaching field data and receives the on-screen schoolteaching data, and synchronously organizes audio data, video data and on-screen data and after fluidizing, provides living broadcast service for the synchronous courseware browsing tool and provides programme ordering service. The invention achieves the characters of powerful functions, high efficiency and short cut, simple and convenient operation, friendly man-machine interface, etc.

The invention discloses a multi-channel high-speed data acquisition system with a synchronous correction function; on the basis of the traditional multi-channel high-speed data acquisition system, a synchronous reference signal generator is added in the multi-channel high-speed data acquisition system and is used for generating fast rising synchronous reference signals; and a time-to-digital converter is added in each channel and is used for measuring time interval delta tch between the rising edge of the synchronous reference signal simultaneously reaching each channel and the subsequent rising edge of first data synchronous clock of the channel. The position Pch of a corresponding sampling point is calculated in each channel when the rising edge of the synchronous reference signal arrives, and then collected data is processed and displayed according to the positions Pch of the sampling points. In the multi-channel high-speed data acquisition system, the obtained positions Pch of the sampling points are real sampling points closest to the positions of the rising edges of the synchronous reference signals so that synchronous errors of the channels are minor as much as possible; the obtained real sampling points are displayed in an alignment mode; the accuracy of the real sampling points is less than or equal to the error of one +/- sampling clock; the synchronous errors are reduced; and the synchronous accuracies among the channels are increased.

The invention discloses a synchronizing method of a high-speed mobile OFDM system. The method comprises the following steps: utilizing the first 10 identical short lead codes in a frame structure of a wireless LAN (local area network) protocol to determine the coarse synchronizing location; according to the coarse synchronizing location, extracting 2 identical long lead codes in a receiving signal and combining with a sliding window to perform fine synchronization; converting the transmitted known long lead codes into a time domain; calculating the mutual correlation value of the extracted long lead codes and the transmitted known long lead codes; determining the maximum of absolute value of the mutual correlation value and the location index corresponding to the maximum; setting the initial value of the preset sliding window; determining the sliding direction of the preset sliding window according to the location index corresponding to the maximum and the set threshold value index, performing fine synchronization, and determining the initial position of the long lead codes. The synchronizing method is applicable to accurately determining the synchronized position of the received information symbol for the OFDM system under the high-speed mobile vehicle-mounted IEEE 802.11p protocol.

The present invention relates to a display apparatus to synchronize a synchronous signal and an inverter driving signal in response to a display mode, and a control method thereof. A back light unit of the display apparatus makes a back light to dim based on an inverter driving signal, and a dimming frequency of the back light varies in response to a synchronous signal frequency of the image. When a synchronous signal having an abnormal frequency is inputted to the back light unit for several seconds, the back light unit holds the frequency of the inverter driving signal and the frequency of the inverter driving signal varies smoothly in response to the display mode.

The invention discloses a modeling method for the dual-driving synchronous electromechanical coupling characteristic of a walking beam type gantry machine tool and solves the problems that the mechanical characteristics of a coupling part of the walking beam type gantry machine tool are decoupled and modeled. The modeling method is characterized in that the factor that the load of the gantry machine tool moves on a cross beam is considered and the problems that the speed of the dual-driving two-shaft coupling part is decoupled with force can be solved. According to the modeling method disclosed by the invention, the actual conditions of the mechanical characteristics for the dual-driving two shafts during synchronous movement can be accurately reflected and main factors for influencing the asynchronous error of two shafts can be disclosed; and the modeling method provides theoretical basis for measures for reducing the dual-driving asynchronous error.

The invention discloses a method and apparatus for measuring interhamonics of a power grid. The method comprises the following steps of: tracking the power grid by a PLL (Phase Locked Loop), accurately measuring frequency by a zero crossing detector matched with a DSP (Digital Signal Processor): sampling a power grid voltage (current) waveform at a constant sampling frequency, tracking the power grid frequency by the PLL, wherein the output of the PLL is used as a sampling clock of an ADC (Analog to Digital Converter); and then enveloping an extraction signal by adopting an HHT (Hilbert Huang Transform) method, carrying out FFT (Fast Fourier Transform) analysis on the enveloped signal, and finally figuring out information of harmonics and interhamonics of the power grid. The apparatus comprises three voltage transformers, three current transformers, an approximate synchronous sampling unit and an HHT-FFT computing unit. According to the invention, the HHT method is combined with the FFT method, power frequency carriers and envelopes are separated by using HHT and are respectively subjected to frequency spectrum analysis by using the FFT; and when the method and the apparatus are used in an actual power grid, measured harmonics and interhamonics precision and instantaneity meet the requirements of IEC (International Electrotechnical Commission).

The invention discloses a device based on a time-varying sliding mode variable structure control and a cross-coupling two electromagnetic suspension systems synchronous control. The device comprises a time-varying sliding mode variable structure controller which outputs a controlled quantity of a suspension system according to a suspension height error amount so as to suspend a mobile crossbeam quickly and accurately to a given height, a cross-coupling synchronous controller which adjusts synchronization performance of two electromagnetic suspension systems, a driver which drives the two electromagnetic suspension systems based on output signals of the time-varying sliding mode variable structure controller and the cross-coupling controller, and a signal detector which collects a speed and a position signal of the electromagnetic suspension systems. The synchronous control method based on the time-varying sliding mode variable structure and the cross-coupling two electromagnetic suspension systems includes that a single electromagnetic suspension system uses a time-varying sliding mode variable structure control method. The control method of the invention, while keeping such characteristics of the sliding mode variable structure as the strong robustness to the parameter perturbation and the external uncertain interference, improves the response speed of the system.

The invention provides a fuzzy self-adjusting deviation coupling multi-motor synchronous control method. The method comprises the steps that a fuzzy self-adjusting filter controller which is formed bycombining a fuzzy controller and a first-order inertial filter and is used for controlling multiple motors is designed; given rotation speed and torque are used as the input of the fuzzy self-adjusting filter controller; softened rotation speed is used as the output of the fuzzy self-adjusting filter controller, wherein the softened rotation speed refers to the given rotation speed actually received by each motor; a lead correction link is introduced to design a lead synchronization compensator, and the response speed of each motor is accelerated while the start synchronization performance isimproved; in the start process and steady-state running sudden load, a synchronization error is calculated; the dynamic response speed characteristics of the motors are compared; and the effectiveness of the lead synchronization compensator to improve the dynamic response speed of the motors is verified. According to the invention, the synchronization performance of multiple motors at the start and the sudden change of the given rotation speed is improved, and the synchronization performance of multiple motors in steady-state sudden load is improved.

This invention provides a Method, equipment and system to deal with optical orthogonal frequency division multiplexing (OFDM) signal, which is related to the area of communication technology. The mentioned methods include: the receiving terminal receives OFDM signal, and obtains its sample signal. The mentioned OFDM signal is equipped with synchronous training sequence, which is used to achieve synchronization of the receiving terminal and transmitting terminal; the first sample point is obtained according to the mentioned sample signal; the second sample point is gained through the mentioned first sample point, and the starting point of OFDM signal is acquired through the second sample point. This invention ascertains the starting point of OFDM signal by means of three levels synchronization method, which greatly increases the accuracy of obtaining the OFDM starting point, and can reduce achieve synchronization error, and achieve the accurate synchronization of signals in cases of feeble signal.

The invention relates to a synchronizing method for host parameters of a triple redundancy control system, belonging to the redundancy control field and adopting a method of point-to-point request-response combining timestamp to carry out the parameter synchronization to two hosts in the system. The synchronizing method is as follows: after initialization, a new power up host judges whether other host is on line at first. If other host does not on line, operating according to parameters directly and outputting; if other host is on line, sending a request packet to the host, and the request packet comprises a timestamp T1 when the packet leaving; and then the online host receives the request packet and fills a time stamp T2 when the packet arriving, the parameters that need to be synchronized is packed, a time stamp T3 when a respond packet leaving is filled in and is sent back to the new power up host; the new power up host receives the respond packet and fills a time stamp T4. According to the four timestamps, the network delay (T4 minus T3) from sending the respond packet by the online host to receiving by the new power up host and a clock excursion theta between two hosts are calculated, and a synchronic parameter is corrected by the value of (T4 minus T3) plus theta. The method of the invention eliminates the affect of clock excursion and network delay to the parameter synchronization, solves the output change when the system host switches and ensures the stability and reliability of the system.

The invention provides a twin-rudder synchronization control method of a ship, comprising the following steps of: detecting the actual deviation of rudder angles of two rudders by taking the rudder angle of one rudder as a standard; acquiring a compensating command signal of the rudder angle of the other rudder through compensation network processing by taking an actual deviation signal as an input signal of a rudder angle synchronization compensation network, and inputting the compensating command signal into a servo system of the other rudder to form closed loop feedback control. The twin-rudder synchronization control method is suitable for the navigation and attitude control of the ship with the two rudders and enhances the accuracy and the sensitivity of twin-rudder synchronization because the compensation network can correct the deviation of the rudder angels in time when the deviation is generated between the two rudder angles.

The invention provides an intelligent substation secondary equipment test platform based on all-digital real-time emulation. A real-time data forwarding platform comprises a digitization interface device. The digitization interface device comprises a computer case, a base plate, a power source plate, a synchronous plate and function plates, wherein the base plate, the power source plate, the synchronous plate and the function plates are located in the computer case, the number of the function plates ranges from one to six, and the base plate provides a power source bus and a synchronous bus for the digitization interface device through the inserted power source plate and the synchronous plate. The digitization interface device is communicated with the Ethernet through a hundred M exchanging chip and an emulation system computing platform, the synchronous plate receives and decodes an external synchronous signal and sends the decoded synchronous signal to the synchronous bus, and all function plates are connected with the synchronous bus to guarantee clock synchronization. According to the provided test platform, the digitization interface device which is of a computer case structure is adopted in the real-time data forwarding platform, and the number of the function plates inserted into the digitization interface device can be selected according to the scale of an intelligent substation to be tested.

The invention relates to a distributed measuring system for the noise of a wind turbine. The system comprises an acoustic measuring end machine, a wind turbine operation parameter measuring node, a wireless communication base station, an acoustic signal processing center, a meteorology and wind turbine data processing center, and a system control, display and interaction center. The acoustic measuring end machine is installed on a noise measuring position, and the wind turbine operation parameter measuring node is installed on a wind turbine; the acoustic measuring end machine and the wind turbine operation parameter measuring node carry out data communication with the wireless communication base station through a wireless mode, acoustic data reaches a first processing center via the wireless communication base station, and the first processing center processes the acoustic data; wind turbine data is transmitted to a second processing center via the wireless communication base station, and the second processing center processes the wind turbine data; and the system control, display and interaction center is used for realize control and data transmission of other modules in the measuring system, interaction with users, and display measuring data and a processing result.

The invention relates to a single-phase ground fault locating method based on zero sequence voltage starting. Zero sequence voltage is adopted as a single-phase ground fault break variable starting component, when a ground fault appears, a bus zero sequence voltage starting device can record zero sequence voltage waveforms at the break moment T, three-phase current waveforms of all high-precisiontransient wave recording type fault indicators installed along a transformer substation outgoing line at the same moment are called, and finally fault positioning is achieved based on wide area synchronous information. The purpose of single-phase ground fault locating in an existing power distribution network is achieved.

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 brings forward a large-scale wireless sensor network time synchronizer based on clock frequency dynamic detection. A rapid tracking strategy is performed on the abruptly changed clock frequency nodes via statistic analysis of clock frequency data so that the nodes are ensured to monitor the clock frequency state in real time. A multi-hop path selection mechanism is adopted, and a synchronization path with great quality is simply and rapidly selected so that a synchronization error multi-hop accumulation phenomenon is effectively inhibited and synchronization precision is enhanced. Strategies of root node reselection and level information periodic updating are respectively adopted by aiming at the situation of failure of root nodes and common nodes in a large-scale wireless sensor network.

The invention relates to a satellite communication network time synchronization method based on centerless TDMA, which comprises the following steps of: firstly, when a network is initialized and a synchronization time slot is allocated, a round-trip timing message length, the maximum satellite-ground propagation time delay and a round-trip timing response message sending time interval designed for reducing a network synchronization error are comprehensively considered; secondly, after receiving a round-trip timing inquiry message sent by a ground node, a satellite node repeatedly sends a round-trip timing response message containing the sending time; and finally, the ground node can calculate a satellite-ground synchronization time error according to the received two round-trip timing response information messages, so that accurate time synchronization of the ground node and the satellite node is realized. According to the time synchronization method provided by the invention, the asymmetry of satellite-ground round-trip transmission time delay and the influence of satellite-ground long-distance transmission time delay on network synchronization are comprehensively considered, sothat the centerless TDMA network realizes accurate synchronization under the condition of satellite-ground long-distance communication.

The invention discloses a prestressed tensioning system. The prestressed tensioning system comprises a master controller as well as a first slave controller and a second slave controller which are respectively and wirelessly connected with the master controller through wireless data transmitting modules; both the first slave controller and the second slave controller are connected with jacks through frequency converters, variable frequency motors and hydraulic pumps in sequence; the two jacks are separately connected with pressure sensors for acquiring pressure of oil inlets and displacement sensors for acquiring the displacement of pistons; the pressure sensors and the displacement sensors are used for transmitting acquired signals to the corresponding slave controllers; the acquired signals are transmitted to the master controller through the slave controllers; the mater controller and a remote monitoring center perform data transmission through a GPRS (General Packet Radio Service) wireless network module; the remote monitoring center is provided with a central server and a terminal; the terminal is connected with the central server through an Internet network. According to the prestressed tensioning system disclosed by the invention, the master controller is used for comparing acquired data of the two jacks and transmitting instructions to the variable frequency motors for enabling the two jacks to synchronous tensioning, so high degree of automation is realized.

The invention relates to the field of dual-motor system control, and provides a dual-motor gear transmission system torque equalization control method so as to realize effective inhibition for output torque imbalance and control dual-synchronization in rotating speed and torque of the system. The invention adopts the following technical scheme: the dual-motor gear transmission system torque equalization control method comprises the steps of (1) a structural model of the system; (2) torque synchronization error calculation, wherein Te1 and Te2 are supposed to be electromagnetic torques of a motor 1 and a motor 2 respectively, a torque synchronization error of the system is defined as E(s)=Te1(s)-Te2(s), E serves as a feedback variable and acts on a synchronization controller, and the size of E reflects the performance of system torque equalization control; and (3) synchronization controller design. The method provided by the invention mainly applied to dual-motor control occasions.