768results about How to "High synchronization accuracy" patented technology

Time information which is to be transmitted via a data packet network is called up from a time information source and is transmitted to a data packet transmission module. The data packet transmission module controls the transmission time of a data packet in which the time information is transmitted via the data packet network. The transmission time and the calling of the time information are aligned with respect to one another in time by a transmission signal which is generated by the time information source or by the data packet transmission module and indicates the transmission time.

The invention discloses a method and a device for synchronizing a master clock and a slave clock, the method comprises: sending synchronous request message to the master clock for many times in a simultaneous cycle by the slave clock, recording the corresponding the time value, then, utilizing a median average filtering algorithm to obtain the optimum time migration amount, utilizing the time migration amount to adjust the slave clock, eliminating the delay inequality which is caused by stochastic disturbance and burst interference of a network communication channel between the master clock and the slave clock, guaranteeing the stability of slave clock signals, and increasing the synchronous preciseness of the master clock and the slave clock.

The invention discloses an embedded real-time emulation and fault simulation system based on multiple data buses, comprising upper computer simulation management software and an embedded real-time emulation and fault simulation device. The upper computer simulation management software guides the user to perform emulation configuration and fault setting aiming at a fault-tolerant control system to be tested through a human-computer interface, and generates fault emulation data of multiple redundancy equipment. The embedded real-time emulation and fault simulation device outputs the fault emulation data in real-time and synchronously through the multiple data buses, simulates the fault of the multiple redundancy equipment and outputs the fault data stream. The upper computer and a lower computer communicate mutually through an Ethernet to achieve the downloading of the information configuration, the fault emulation data and the emulation control command of the upper computer, and the uploading of the working condition of the lower computer. The invention overcomes the defects of poor universality and lower synchronous precision of the traditional multiple equipment fault simulation device based on the emulation, and is suitable for the test and the verification of the different redundancy fault-tolerant designs of the complex spacecraft system with numerous equipment and frequent data exchange.

The invention relates to a tunnel lining disease detection device based on an infrared temperature field and a gray level image. The tunnel lining disease detection device comprises a vehicle-mounted mobile platform, illumination equipment, a photoelectric encoder, a GPS (Global Position System) receiver, an inertia unit, a synchronous controller, an area-array camera, an infrared thermal imager, an acquisition server, a display control device and a power supply system; tunnel lining two-dimensional image data, infrared temperature field data and fracture surface deformation data are combined with positioning data of the GPS, the inertia unit and the photoelectric encoder to establish a tunnel model with gray level information, temperature information and fracture surface deformation; and tunnel lining cracks are analyzed, and the length, width and lining leakage water information of the cracks are automatically detected. For the tunnel lining disease detection device, the advantages of infrared temperature field detection and two-dimensional gray level image crack detection are combined so that the detection result is relatively reliable, the speed is rapid and the working efficiency is greatly improved.

The present invention discloses a low signal-to-noise ratio short preamble burst signal demodulation system and method. A burst signal detection module detects in real time whether a received signal includes an MPSK signal, if the received signal includes the MPSK signal, an initial position and an ending position of the MPSK signal are offered; then, a coarse frequency synchronization and time synchronization module realizes time synchronization point tracing and coarse frequency offset correction of the signal according to the preamble of the burst signal and the initial position of the MPSK signal; then, sampling timing synchronization and fine frequency offset compensation and phase offset correction are respectively performed by a timing synchronization module and a fine frequency synchronization module on the signal; and finally, a phase unwrapping and de-mapping module completes phase unwrapping and bit decoding. According to the method, time synchronization of the demodulation system is before timing sampling synchronization, a parameter estimation module is reused, while the processing time is not increased, the accuracy of coarse frequency estimation and time synchronization is greatly improved, and hardware resource consumption is reduced greatly.

The invention discloses a synchronous realizing method in the orthogonal frequency-division multiplying system, which comprises the following steps: constructing front / synchronous sequence at the transmitting end to frame and transmit; combining the CP information to do one-time synchronization; utilizing front symbol to estimate the integral times and decimal time-domain frequency deviation; compensating the frequency deviation; using front symbol to do secondary time synchronization; proceeding disposal after synchronizing. The invention improves the synchronous precision to modify the system property as well as the received signal-to-noise ratio, which reduces the calculating quantity without adding the burden of system.

The invention relates to multimedia real-time transmission in packet network, disclosing a lip synchronizing method and device for multimedia real-time transmission in packet network, able to simply and effectively regulate to overcome network dithering and variation and implementing lip synchronization of audio and video streams. And it sets buffers which can flexibly regulate buffering time length according to network time delay information and implement synchronization of audio and video streams by regulating their buffering time lengths; it sets a time delay detection module to detect transmission time delays of audio and video data in packet network and then uses synchronizing module to refer to their average transmission time delay and transmission time delay so as to synchronize audio and video modules; it uses the synchronizing module to calculate buffer-storing time lengths of audio and video buffers and flexibly sets them to resist network transmission dithering; it makes one of the audio and video parties regularly transmit synchronous time reference point to the other one so as to coordinate their synchronization.

The invention discloses a method used for capturing carrier frequency offset and time delay in a single-carrier frequency domain balancing system, comprising the steps as follows: frame-arrival detection is carried out on the received data; when effective data frame is detected, the frame head position of the data frame is determined roughly; the determined frame head position is used as an initial position to carry out rough frequency offset estimation and compensation on the received data frame; the rough timing estimation is carried out so as to determine the initial position of the data block; the timing deviation is locked within one code element offset; the precise timing estimation is carried out by combining a maximum-likelihood searching method with an O&M timing estimation arithmetic, thus gaining precise code element timing information; precise frequency offset estimation and compensation are carried out; synchronous error lock judgment and correction are carried out. The method designs unique preamble code data form and structure, precisely carries out the estimation and compensation on carrier frequency offset and time delay during the synchronous capturing stage,gains precise carrier frequency offset and timing information, and determines the initial position of Fourier transform windows more exactly.

The invention provides a precise time synchronization method for an industrial wireless network, relating to the industrial wireless network communication technology. Aiming at the characteristics of the industrial wireless network, such as limited energy supply, dynamic and variable network environment, the openness of the wireless network media, and the like, the invention provides a unique precise time synchronization method, wherein, a layering and grading synchronization strategy is adopted to divide the industrial wireless network according to a hierarchical structure; an MAC layer of a parent device generates beacon frames, sends the beacon frames periodically, obtains a time stamp in the processes of sending and receiving beacon frames, obtains the frequency deviation and time deviation of the equipment clock and the universal time clock by fitting the time stamps sent and received in most recently N times, compensates the local clock, realizes the time clock synchronization of a child device and the parent device; time synchronization is carried out in a grade-wise manner and finally the time synchronization of the whole network is realized. On the premise of meeting the performance requirements on the industrial wireless network, the precise time synchronization method of the invention can ensure that the whole network runs within a uniform time scale and guarantee the normal operation of the system.

The present invention discloses a multipoint synchronous lifting equipment and its lifting method. Said multipoint synchronous lifting equipment is formed from synchronous control cabinet, hydraulic lifting device and displacement sensor. Every lifting point is correspondently equipped with a set of hydraulic lifting device and displacement sensor. Besides, said invention also provides the concrete operation steps of said lifting method.

In an oversampled orthogonal frequency-division multiplexing (OFDM) orthogonal network, the preamble used for time synchronization does not have an ideal autocorrelation function due to guard bands, which degrade the accuracy of symbol timing. Therefore, a zero-correlation-zone (ZCZ) based preamble is used for time synchronization. Across correlation function (CCF) used for time synchronization is forced to 0 within a certain region around a main lobe. The length of the ZCZ is guaranteed to be larger than a cyclic prefix length of OFDM data symbols synchronization accuracy.

The invention discloses a method for real-time synchronization and dynamic compensation between chain Ethernet nodes. The method is simple, convenient and lower in cost, and fewer software and hardware resources are occupied. The method comprises the following steps that: 1, a master node starts enumerating each slave node; 2, a zero node which is the first of the slave nodes starts a cycle timer, and implements management over a bus cycle in a way of cyclically transmitting a synchronization packet; 3, the synchronization packet starts delay measurement modules of the slave nodes for timing, and is continuously transmitted until being transmitted to the last slave node; 4, the last node constructs and uploads a standard Ethernet data packet; 5, each slave node stops the timing when receiving a returned packet, and starts a local distributed clock by taking a half of a measured value as an initial value; and 6, after completely receiving control data, the slave nodes generate synchronous signals when the time of each synchronization clock is the same, execute corresponding operations, latch a current state and wait for uploading.

The disclosed transmission system for mobile digital multimedia broadcast signal comprises: a channel coder to receive, code and interlace data flow to transform it into bit flow; a constellation mapper to map the bit flow into QAM, BPSK or QPSK signal flow; an OFDM signal forming module to insert the continual and discrete pilot frequency into last signal flow and load on the service sub-carrier to form OFDM signal; a framing module to add beacon into the OFDM signal and form transmission frame; and an up-conversion module to generate RF signal for transmission. It also discloses corresponding transmission and allocation method.

A synchronies method of wireless sensor network time based on error statistics includes steps: uses the flood course of synchronous command message to reach the time synchronism with low accuracy in short time, and build network tree hierarchical structure at same time; dynamic choosing part or whole edge nodes of network are the delay statistical node; statistical synchronizes message is from concourse nodes to delay statistical node, and delay statistical message is from delay statistical node to concourse node; calculates the transmission delay of every jump; compensate the synchronizing accuracy according to transmission delay of every jump and the jump number of concourse node to reach the time synchronism with high accuracy, which is used in wireless transmission network, containing concourse node and sensor node, and all nodes are tree structure whose root nodes are concourse node. The method has good adaptability, extension, and high synchronism accuracy, and it has good split between synchronism accuracy and power consumption.

The invention discloses a method for synchronizing the time of a wireless sensor network and belongs to the technical field of the wireless sensor network. The method comprises the following steps that: 1) a central node broadcasts synchronization information to a network at a specific time interval and starts a synchronization process; 2) after receiving the synchronization information, a sensornode synchronizes time with a source node of the synchronization information and broadcasts the synchronization information thereof to the network when a channel is free; and 3) after each synchronization process is completed, the sensor node predicts the working frequency of a crystal oscillator configured per se in the current period by a winters method and corrects the logic time thereof according to the prediction result till the start of the next synchronization process. Compared with the prior art, the method can greatly prolong the time interval of period synchronization and reduce synchronization expense and the occupying of a wireless channel and improve the synchronization precision among nodes.

Multipoint broadcasting requires the base stations to be phase-synchronized. Methods and apparatus are described that provide phase synchronization of base stations with the downlink-channel phase feedback by mobile users. Also described are methods and apparatus that make phase synchronization of base stations independent of multipoint-broadcast sessions, thus reducing the synchronization overhead and improving network capacity. The methods and apparatus utilize model-based downlink-channel phase feedback that reduces most of the feedback overhead. Applications of the described methods and apparatus include wireless multipoint broadcast systems, also known as coordinated multipoint transmission, or CoMP, in LTE-A (long-term evolution, advanced) systems, and frequency and phase synchronization of a cluster of base stations, or more generally, of a cluster of wireless devices.

The invention discloses a realizing device of a penetration clock, and a method thereof. The device is composed of a clock module, a data identification module and a data modification module, wherein the data identification module and the data modification module are respectively connected with the clock module which is used for providing clock information for the data identification module and the data modification module; the data identification module is used for receiving data and obtaining current time information from the clock module; the data modification module is connected with the data identification module, and is used for adding the positive value or the negative value of the current time information with time information carried in data according to the output direction of the data and outputting the added time information and the data. Because of the invention, time information of the data residing in an exchange node is obtained by a hardware device, and the time information is modified according to the residency time information. The invention can effectively realize the penetration clock of the data, and has the advantages that the information accuracy of the obtained residency time information is high, and the obtaining form is stable.

The invention provides a centralized method for realizing 1588 time synchronization on a distributed system, and relates to the field of 1588 time synchronization. The method comprises: a master clock node sending a synchronization message, carrying t1 and t1'-t1, t1' being time when a same node wire board sends the synchronization message, a slave clock node receiving the synchronization message, marking t2' and t2, calculating a synchronization message correction time delay value; the slave clock node sending a delay request message, carrying t3 and t3'-t3, t3' being the time when the same node wire board sends the delay request message, receiving the delay request message by the master clock node, marking t4' and t4, calculating a delay request message corrected delay value, inserting the delay request message corrected delay value and the t4 into a delay response message, sending to the slave clock node, the slave clock node obtaining all timestamps and two corrected delay values, through a time synchronization algorithm, completing time synchronization. The method can reduce development and debugging workload, simplifies backboard wiring, reduces synchronizing signal interference, and shows for the external by integrated time source information.

An audio and video synchronizing method in a network monitoring system includes that (1) videos are compressed through self hardware compression of a chip TW2835 to generate H.264 data, audios are compressed through software compression to generate a G.729 data format, and the H.264 data and the G.729 data are transmitted to an RTP (real time protocol) database to be packaged and transmitted; (2)after IP (internet protocol) packet headers and UDP (user datagram protocol) packet headers of data packets received from the network are removed, an RTP packet is decided to place into an audio or video buffer area according to load type in an RTP packet header, and load data in the RTP packet are inserted into the correct position of the buffer area according to sequence of serial number fields in the RTP packet; proper data packets are pre-stored in the audio or video buffer area after network data are started to be received; after data of audio and video streams are full of a prestorage area, playing is started; the audio stream is used as time dominant in synchronization, and audio and video synchronization is realized by adjusting video targets. The audio and video synchronizing method is simple to implement and high in synchronization accuracy.

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.

The method includes following steps: constructing leading / synchronizing sequence on each transmission antenna, as well as carrying out framing and sending operations; carrying out once time synchronization by combining with cycling prefix information on each receiving antenna; using the leading symbols to carry out frequency deviation estimation (FDE) in time domain in integral multiple and decimal multiple for each receiving antenna; merging in equal gain for value of FDE on each receiving antenna so as to obtain final average value of FDE, and carrying out compensation of FDE for data of each receiving antenna; using leading symbol to carry out second synchronization for time; selecting best point of second synchronization for time; using the obtained best point to carry out synchronous post-processing. Satisfying precision required by operation, the invention raises SNR for received signal, does not use too much system resources, and increase redundancy of system, etc.

The invention discloses a fusion network system for quantum communication and quantum time-frequency transmission and method. A quantum relay unit transmits entangled photon pairs and transmits the entangled photon pairs to two quantum terminal units through transmission units respectively; the quantum terminal unit reflects input photons, and the photons are returned to the quantum relay unit through the transmission unit; the quantum relay unit performs HOM interference measurement on the entangled photon pairs, optical path delay is adjusted, the maximum HOM depression value is obtained through multiple times of measurement, and optical path balance is realized. Later, a signal laser transmits laser pulses to the quantum relay unit through the transmission unit, the quantum terminal unit codes the input laser pulses and transmits the laser pulses to the quantum relay unit through a transmission channel, the quantum relay unit obtains a result, an acquired key is published through aclassical channel, clock synchronization is carried out through the classical channel and by using an optical channel monitor, time-frequency information is encrypted through a key distributed by QKD,and thus, the time-frequency information security problem is solved, and fusion between quantum communication and quantum time-frequency transmission is realized.

The invention relates to a method for synchronizing a first clock C to a reference clock A, the first clock C being connected to said reference clock A via a processing unit B. The invention moreover relates to a processing unit B and to a synchronization system. In order to enable a synchronization of said first clock C to said reference clock A via said processing, unti B. it is proposed that the processing unit B generates a correction message cmsg for the first clock C based on timestamps exchanged between the processing unit B and the reference clock A, which exchanged of timestamps is triggered by clock pulses cclk received in the processing unit B from the first clock C.

Distribution of reference frequency and timing information in a network involves determining latency between a first and second node from time delay between transmission of a reference frequency and timing signal and reception of an optical return timing signal in response. In a network with pairs of first and second optical fibers in optical fiber connections between network nodes, for transmission of optical data signals separately in mutually opposite directions between the network nodes respectively, provisions are made to transmit the reference frequency and timing signal and the resulting optical return signal via the same fiber, one in the same direction as the unidirectional data signal over that fiber and the other upstream. Repeaters between the nodes may be modified to pass such signals upstream and downstream. In an embodiment wherein the network provides for an optical supervisory channel, the optical filters for combining the optical supervisory channel signal with the unidirectional data signal and separating the optical supervisory channel signal from the unidirectional data signal are used to combine and separate the reference frequency and timing signal and to pass the optical return timing signal. For this purpose, further optical filters may be added outside the main optical data channel to combine and separate the reference frequency and timing signal and the optical supervisory channel and to pass the optical return signal back to the filter that separates the optical supervisory channel signal from the data signal.

The invention discloses a high-frequency ground wave radar networking clock synchronization control method which is characterized in that each piece of radar detection equipment in the network is respectively configured with a synchronization control part for high-frequency ground wave radar networking, and clock synchronization between any two pieces of radar detection equipment is realized by the synchronization control part. The method comprises the following steps: 1. selecting one from two pieces of detecting equipment to serve as the master equipment of clock benchmark, and the other equipment serves as the slave equipment for adjusting clock and master equipment synchronization; 2. carrying out shift measurement from the master equipment to the slave equipment, and carrying out delay measurement between the master equipment and the slave equipment; 3. calculating the clock offset of the master equipment and the slave equipment by the synchronization control part of the slave equipment according to the shift measurement result obtained in step 2 and the delay measurement result obtained in step 3; and correcting the work clock of the slave equipment according to the clock offset. The device of the invention has favorable generality, and the synchronization control part is suitable for circuits with any specific function, has high flexibility and is convenient for research personnel to work in cooperation with a due division of labour.

The invention provides a lead pilot-code detection method of a user station receiver, which comprise the following steps: (1) each orthogonal frequency division multiplexing received by an antenna is accessed OFDMA symbols, correlation energy corresponding to each sliding sample point, a symbol serial number corresponding to the maximum correlation energy and the sample point deviation, namely, frame header coarse synchronization position are recorded; (2) the frame header coarse synchronization position is taken as a symbol timing reference to estimate a decimal frequency offset; (3) the estimated decimal frequency offset is used to calibrate the frequency offset of each symbol; (4) a sector number of the lead pilot-code and a fine timing position are detected; (5) a cell identification number of the lead pilot-code is detected, a corresponding lead pilot-code is researched and acquired by using the sector number of the lead pilot-code detected by the step (4) and the cell identification number detected by the step (5). The method provides an important modulation parameter and symbol synchronization for SS receiver data modulation, which can greatly reduce the ID Cell detection calculation capacity and improve the accuracy of the lead pilot-code detection and the symbol synchronization as well as facilitate the achievement of software in practical application.

The invention discloses a method which is used for time synchronization correction in a digital communication network and comprises the following steps: a synchronization protocol module receives a time deviation value sent after the synchronization communication between a main side and a secondary side is finished, and the time deviation value of this time is compared with a time deviation value of last time, if the time deviation value of last time is larger than the time deviation value of this time and the filtering result is less than a predefined threshold, the precise synchronization correction with the correction step size less than the threshold is implemented. The method and a device of the invention which are used for implementing the time synchronization correction adopt the processing of time deviation value and different strategies of synchronization correction according to different processing results and different synchronization phases, thus effectively improving synchronization precision and anti-interference ability, being applicable for the synchronization correction of various communication networks and various synchronization protocols, and having universality.

The invention discloses a method and device for achieving clock time synchronization, and relates to the Ethernet technology. The method comprises the steps of estimating the clock jitter and the clock frequency deviation with the difference of sending and receiving timestamp of a synchronous message packet and the difference of sending and receiving timestamp of a response message packet in a precision time protocol (PTP) message packet as observed values respectively to obtain the phase difference of a master clock and a slave clock, and carrying out the synchronization adjustment on the slave clock according to the estimated phase difference. The invention further discloses the device for achieving the clock time synchronization. According to the technical scheme, the state quantity is obtained by calculating measuring values respectively based on the kalman filtering algorithm and the combination (O+D and O-D) of the phase difference and the path delay, the estimated value for the clock synchronization phase difference is obviously far more superior to the estimated value, worked out through the single measuring value of the phase difference serving as the state value, for the clock synchronization phase difference , the phase difference can be reflected better and the synchronous precision between the master clock and the slave clock is greatly improved.

The invention discloses a synchronization method for orthogonal frequency division multiplexing system, including: the launcher firstly constructs the originated / synchronous sequence that is sent out with OFDM data symbols together. Based on the correlation of CP effective length in OFDM symbols form the receiving end, the correlation result conducts a time domain processing to the correlation sequence energy to get the best synchronization points set after one synchronization. Based on the originated sequence and CP, the departure estimation and departure compensation of fractional part DF several times are processed. During a range of synchronization points set output at once, the long pre-symbol received after the compensation is made time-domain correlation with the symbol to find the second time synchronization point. Then after time-domain of the short pre-symbol and the received pre-sequence is made frequency departure compensation, time-domain-related operations is conduct to get the DF departure estimation of integer times, and departure compensation is conduct.

The invention provides a two point four gigahertz full-channel data collection and protocol analysis instrument based on the IEEE802.15.4, and relates to the technical field of wireless sensor networks. The system comprises 16 radio frequency receiving modules. Each radio frequency receiving module is in charge of unceasingly monitoring whether a wireless data message exists in a channel of the network in the 2.4 GHz ISM band or not. A data management module reads an interrupt mark in a wireless module through polling, reads the data message from the FIFO of the corresponding radio frequency receiving module, detects whether the data message confirms to the standard format of the wireless data message or not and processes the data message. The data message enters a corresponding analysis module according to a selected protocol, data packet information is analyzed field by field, the analyzed information is stored in a database to form a new data message, and the new data message is uploaded to an upper computer by calling an application program. The system further has the channel scanning function, and quality index numbers of all current channels can be obtained in real time.