132results 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 synchronous control system of ultra-sophisticated dual-layer macro and micro movement platform which includes a main control module set in a computer, two macro and micro movement platform control modules and a synchronous control module; two macro and micro movement platform control modules also include a micro movement platform control module, a follow control module, a macro platform control module, a laser measure module, and a grating measure module. The invention provides a micro movement platform position converter that can simplify the micro movement platform control; a force action converter that can increase follow precision of the macro movement platform. The control method using the macro movement platform to follow the micro movement platform can prevent the micro platform moving saturation, increase location precision of the macro and micro movement platform; the double-layer macro and micro movement platform synchronous controller can reduce synchronous error, and improve synchronous precision of the double-layer macro and micro movement platform. The synchronous control system can be used in a numerical control machine moving system, also can be used in other precious location system such as MEMS.

Disclosed is a layered time comparative clock synchronized method in the wireless sensor network, which belongs to the wireless network technology field. The method comprises the following steps: step one, the network initialization is started, and the network is layered from a basic station / a coordinator according to the signal intensity and the device category; step two, the whole network is divided into outer clock source synchronization and inner clock source synchronization, the nodes are synchronized by adopting the timestamp comparative method, and the upper-level nodes and the lower-level nodes respectively take the outer clock source synchronization and the inner clock source synchronization; step three, the synchronizing cycle and the clock drift parameter are regulated according to previous synchronization effects; step four, the old timestamp is automatically discarded. Compared with prior art, the method can better correspond with the accuracy of the wireless sensor network time synchronization method, and has the advantages of low cost and solidity.

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.

A workpiece is rotated by a master motor and a tool is linearly moved by a slave motor to cut a thread in the workpiece. Position feedback of the master motor is multiplied by a coefficient K and the result used as the position command of the slave motor. Provision is made of an angle synchronization learning control unit for storing one pattern cycle's worth of the correction data of the threading and adding the same to the position deviation. This control unit stores one pattern cycle's worth of the correction data corresponding to the position feedback of the master motor. The position is converted to the correction data corresponding to the time at that time based on the stored correction data to find the correction data and this is added to the position deviation.

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 relates to a harmonic analysis method based on asynchronous sampling, belonging to the field of signal harmonic detection technique. The method comprises the steps as follows: 1) a plurality of prearranged weight coefficients corresponding to signal frequencies one-to-one are sequentially memorized in a memory; 2) the harmonics are sampled under a constant sampling period; a sampling signal is output to a digital signal processor after A / D conversion; 3) the digital signal processor processes digital signals which are converted by multi-path A / D converters, and according to the frequencies, the positions of the weight coefficients needed to be invoked in the memory are determined; 4) in the digital signal processor, corresponding weight coefficients invoked in the memory is multiplied by the input digital signals, subsequently, FFT processing is carried out; and 5) the FFT-processed result is displayed or printed. The method overcomes the synchronous difference problem of the harmonic analysis, obtains real-time harmonic analysis signals with high precision, and can be applied to the signals in the fields such as machines, power, information, geology, hydrology and the like so as to carry out the harmonic analysis.

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.

Two-phase sinusoidal signals QA, QB output from an encoder are interpolated by sample-and-hold (S / H) circuits and A / D conversion (ADC) circuits, and data D is output in accordance with a data request signal RQ from exterior. For this interpolation of encoder output, a direction discrimination up / down counter is arranged near a two-phase square-wave uniform pulse generating circuit, and the data D is latched and output using a signal which is obtained by delaying the data request signal RQ. This can reduce synchronization errors between the data request signal RQ from exterior and the interpolated data, with an improvement in dynamic precision.

A method for time synchronization in a distributed control system includes the steps of: when a sync is received from a master-side, confirming both a reception time point of the corresponding sync and a compensation time point of a previous frequency, and determining if a result obtained by confirming the two time points corresponds to a preset Frequency Compensation Interval (FCI); performing only a time offset compensation operation when the result obtained by confirming the two time points does not correspond to the preset FCI; and performing both time offset and frequency compensation operations when the result obtained by confirming the two time points corresponds to the preset FCI.

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 discloses a vehicle inertia motion data acquisition unit, which comprises a sensor, a signal conditioning circuit, a synchronous acquisition circuit, a data interface and an embedded memory system, wherein the sensor includes an acceleration transducer and an angular velocity transducer; the synchronous acquisition circuit includes a single chip microcomputer, a analog-to-digital (AD) conversion chip and a global position system (GPS) module; the data interface includes a universal serial bus (USB) device terminal control chip and a USB device terminal interface, the acceleration transducer and the angular velocity transducer are electrically connected with the signal conditioning circuit; the signal conditioning circuit is electrically connected with the AD conversion chip of the synchronous acquisition circuit; the AD conversion chip and the GPS module are connected with the single chip; the single chip are connected with the USB device terminal control chip of the data interface; the USB device terminal control chip is connected with the USB device terminal interface; the embedded memory system is connected with the USB device terminal interface of the data interface through a USB client interface. According to the vehicles inertia motion data acquisition unit, the safety performance of the vehicles is remarkably improved.

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.

A workpiece is rotated by a master motor and a tool is linearly moved by a slave motor to cut a thread in the workpiece. Position feedback of the master motor is multiplied by a coefficient K and the result used as the position command of the slave motor. Provision is made of an angle synchronization learning control unit for storing one pattern cycle's worth of the correction data of the threading and adding the same to the position deviation. This control unit stores one pattern cycle's worth of the correction data corresponding to the position feedback of the master motor. The position is converted to the correction data corresponding to the time at that time based on the stored correction data to find the correction data and this is added to the position deviation.

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 relates to a distributed variable sampling rate synchronous data acquisition device based on an Ethernet. The device comprises a machine case and a bottom plate. The device is characterized by further comprising a power supply module, 1-15 synchronous data acquisition modules and an Ethernet switch which are integrated on the bottom plate. The input end of the power supply module is connected with an external 220V AC power supply. The output end of the power supply module is respectively connected with the synchronous data acquisition modules and the Ethernet switch. All the synchronous data acquisition modules share the same difference sampling clock signal to perform data communication with a far-end host via the Ethernet switch. Synchronous acquisition of as many as 180 paths of analog signals can be met, and configuration is flexible and scalable performance is high with minimum synchronous error of all the synchronous data acquisition modules so that a strictly synchronous coherent relationship can be maintained. Requirements of multichannel, distributed, variable sampling rate and synchronous data acquisition are met so that the device is particularly suitable for long-time, high-capacity, multi-input and full-isolation data acquisition occasions.

The invention relates to an underground multi-node signal acquisition synchronous error correction device. A delay measuring unit of the device simulates a PPS (pulse per second) and sends a PPS signal to pulse receiving and forwarding modules at acquisition nodes of a seismic signal acquisition system through a logging cable, a telemetering unit and an interstage cable, and measures time consumed by sending the PPS to the acquisition nodes and passing back to the ground; and a delay correction unit calculates a delay correction amount according to each pulse measuring time, and seismic signal data collected by each acquisition node are delayed for corresponding time according to each delay correction amount and are the repackaged into independent data. The underground multi-node signal acquisition synchronous error correction device provided by the invention can accurately measure and correct transmission delays of all nodes, breaks through the limitation to the number of nodes, solves the problem that cable delay reaches up to several hundred of microseconds, and can reduce a synchronous error of seismic signals collected by multiple nodes to a nanometer scale, thereby realizing high-precision synchronous acquisition of all nodes in a system.

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.