77 results about "Coordinate time" patented technology

A method and apparatus of coordinating Time Division Multiple Access operation of wireless communication devices is disclosed. The method comprises an access point announcing a Quiet Period to one or more clients of the access point and transmitting as part of Target Beacons and probe responses an indication to the one or more clients that the access point will be absent from the communication channel for a period of time. The method also comprises the one or more clients establishing a connection with the access point after the Quiet Period when the access point is present on the communication channel on the basis of the indication.

A method and apparatus for allocating resources of a Visible Light Communication (VLC) terminal in a VLC system. The VLC terminal receives a beacon message from a base station, coordinates time synchronization with the base station, searches for an available wavelength channel, constructs available wavelength channel information, and transmits an initial access request using a basic time slot channel and a basic wavelength channel. The base station considers the available wavelength channel information and a current channel allocation condition, allocates an appropriate channel, and transmits channel allocation information to the VLC terminal. The VLC terminal and the base station communicate data with each other using an allocated time slot channel included in the channel allocation information and an allocated wavelength channel included in the channel allocation information.

The invention provides a software time synchronization method for a position and orientation system (POS). The POS comprises an inertial measurement unit, a POS navigation computer, a GPS (Global Positioning System) receiver and the like. The time synchronization method comprises the following steps of: firstly synchronizing system time of the POS navigation computer to world coordinated time by using a GPS second pulse sent by the GPS receiver and a time counter; and synchronizing the data acquisition time of the inertial measurement unit with the world coordinated time through a method of correcting a frequency division period of a data acquisition pulse clock of the inertial measurement unit so as to complete the time synchronization of the POS. In the invention, the problem of reducing of synchronization accuracy of the POS in a short time due to the clock drift is solved through the method of changing the frequency division period of the data acquisition pulse clock, and the software time synchronization method has the characteristics of high accuracy and high anti-interference capacity.

A medical kinematic analysis apparatuses includes a tracking point coordinate acquiring unit to generate coordinate time series data representing a coordinate of a tracking point on a heart from the time series image data, a motion information acquiring unit to generate time series motion information of the tracking point from the coordinate time series data, a first motion component computation unit to compute a motion component of a cardiac systole/diastolic direction from the time series motion information, and a second motion component computation unit to compute a motion component of a direction different from the cardiac systole/diastolic direction from the time series motion information.

The invention provides a method for acquiring noise models of coordinate time series of regional GPS (global positioning system) reference stations. The method includes steps of 1, collecting data; 2, selecting a plurality of groups of combined noise models according to a basic principle that the noise models cover integral frequency bands of noise frequencies; 3, respectively analyzing noise of the coordinate time series of the GPS reference stations and noise of environmental-load-corrected coordinate time series of the GPS reference stations by the aid of a maximum likelihood estimation process according to the various combined noise models, and acquiring MLE (maximum likelihood estimation) values of the various combined noise models at components of the coordinate time series of the GPS reference stations; 4, acquiring the optimal noise models at the components of the coordinate time series of the GPS reference stations according to the MLE values of the combined noise models. The method has the advantages that the optimal noise models of the regional GPS reference stations can be effectively built, nonlinear movement is taken into consideration of the optimal noise models, accordingly, actual movement of the observation stations can be effectively represented as compared with existing models, and noise signals which are reflected by the coordinate time series can be reasonably explained.

The invention discloses a GNSS base station crustal movement velocity estimation method in consideration of nonlinear change. In consideration of the influence on the base station velocity estimationby the GNSS base station nonlinear change, a random model and like, the latest resolving strategy is adopted to acquire a GNSS base station coordinate time sequence under an ITRF2014 framework, a timesequence model for performing separation on the nonlinear change of the base station coordinate time sequence is established by combining a real physical correction model, abnormal location gross error and step detection and like methods; and a GNSS base station coordinate time sequence background noise model determination technology based on the singular spectrum analysis method is adopted, andan improved Bayes information minimum criterion noise model estimation method is proposed base on above conditions, a GNSS base station crustal movement velocity field estimation method is provided, thereby providing accurate and reliable velocity field data basis for the crustal movement velocity field estimation.

The invention provides a periodic detection method and system for a GNSS observation station coordinate time sequence. The method comprises the steps of acquiring a GPS observation station coordinatetime sequence observed value, removing gross errors and correcting an antenna phase center deviation; performing preliminary spectrum analysis on the GPS observation station coordinate time sequence by using a periodogram method; acquiring a plurality of major cycle frequencies of a corresponding observation station, and sorting according to the amplitudes of main frequencies; describing the GPS observation station coordinate time sequence by using a harmonic function, acquiring a harmonic function model of the GPS observation station coordinate time sequence, and building a harmonic functionmodel matrix; using the main frequencies as prior constraints, and acquiring the standby frequencies of a plurality of periodic signals; resolving the harmonic function model based on a least squarescriterion, acquiring optimal frequencies and verifying the standby frequencies by using a hypothesis testing method, and building the harmonic function model including the plurality of optimal frequencies; and according to the standby frequency after hypothesis testing is performed, resolving the harmonic function model matrix based on the least squares criterion, and acquiring a detection resultof any GNSS observation station periodic signal.

This invention relates to a managing method for coordinating consistency of time by multiple nodes including two parts: 1, carrying out role and hierachical decomposion to nodes in a distributibve system according to functions and logic relations, 2, the time synchronized hierarchical association flow of the nodes includes the following steps: 2.1, the distributive member nodes send push time request to process internal messages and push the time, 2.2, a local time coordinator caries out information maintenance and time synchronization to member nodes in its coordinated sphere, 2.3, a global time coordinator maintains information and synchronizes time for all local time coordinators.

The invention discloses a method for calculating green wave effective coordinated time. For monitoring the running state and control effect of a trunk line green wave coordination control system to determine the switching time points of different trunk line traffic signal control schemes, a definition and a calculation method of effective coordinated time are firstly given, the running state of a current green wave coordination control system is dynamically monitored, a bottleneck intersection in a green wave coordination system is determined by accumulating punishment score values, and the influence of effective coordinated time on the switching time points of the signal control schemes is discussed lastly. As shown by a simulation test result, the running state of the green wave coordination control system can be effectively monitored by adopting the effective coordinated time, the bottleneck intersection in the system is discovered accurately, and technical support can be provided for improving a trunk line traffic organism and perfecting a trunk line control scheme.

The invention discloses a method for stability analysis of reference point for GNSS automatic deformation monitoring, which comprises the following steps: calculating the GNSS observation data to obtain the coordinate residual time series of the reference point; detecting and removing rough errors in the coordinate residual time series of the reference point; extracting and removing the linear trend and the cyclical term in the series; conducting interpolation to the time series if there exist missing data in the coordinate residual time series after the removal of the trend and the cyclical term; extracting the common-mode error of the residual time series and removing the common-mode error from each residual series; and finally, using a quantification calculating method to determine whether the remaining residual series follows a normal distribution or not. If it is, then the reference point is regarded as stable; otherwise, instable. According to the invention, it can effectively eliminate the common error of a station, improve the signal-to-noise ratio of the coordinate time series, and finally make the main error of the coordinate time series of the station limited to observed random noise to judge whether the station is stable or not.

The invention provides a correlation coefficient-based method for weakening the CME (common mode error) influence in a coordinate time sequence. The correlation degree of the GPS (global positioning system) measuring interstation coordinate time sequence is represented by adopting correlation coefficients between a reference station and common measuring stations, and the correlation coefficient is used as the weight for calculating the GPS measuring interstation common-mode error. Meanwhile, the GPS measuring interstation negative correlation is not omitted, a positive correlation and a negative correlation are substituted into the CME calculation system at the same time, positive and negative correlation are equally treated as the weight factor for measuring the GPS measuring interstation CME influence. According to the correlation coefficient-based method, the technical problems that the existing method for weakening the CME influence in the coordinate time sequence is limited in interstation distance, low in space accuracy and the like are solved, and the method can process the measuring interstation CME influence of a GPS network being more than 2000km and can ensure the space response accuracy.

This invention relates to clock synchronous method to fulfill synchronous clock between first and second parts, which comprises the following steps: a, second part receives clock message from first part with current time in the message; b, the second part coordinates time according to second part. This invention also discloses one first and second part of this method.

A method capable of quantitatively evaluating two-dimensional patterns and a system to which the method is applied are provided. In the present invention, a reference coordinate system is set in order to convert pattern edge information (one-dimensional data) acquired by measurement using an existing critical dimension machine into coordinate data. Thus, a pattern is converted into coordinate information. Next, a function formula is determined from this coordinate information by approximate calculation and a pattern is represented by the mathematical expression y=f(x). Integrating y=f(x) in the reference coordinate used when calculating the coordinate data gives the area of the pattern, whereby it is possible to convert the coordinate data to two-dimensional data.

A system and method for reducing the latency from timing deviation (TD) measurement to time advance (TA) adjustment. The invention uses a deterministic procedure to coordinate time advance (TA) commands and timing deviation (TD) measurements so that failed transmissions or mobile terminals signal propagation changes can be recognized and corrected much more rapidly. Radio resource efficiency is maximized by minimizing signaling overhead through effectively reducing the frequency of time advance commands. This is accomplished by using TA command signals which include a Connect Frame Number (CFN) to specify particular radio frames for time advance (TA) adjustment. The potential for timing deviation (TD) measurements to be incorrectly processed in conjunction with adjusting a physical reception window and calculating mobile termination location is minimized, without excessive command signaling requirements.

The invention discloses a method for accurately quantifying influence of a thermal expansion effect on a GPS coordinate time series. The method includes collecting a surface temperature time series of an IGS reference station, and collecting observation station information; calculating the total influence of the thermal expansion effect on an IGS reference station coordinate time series, i.e., Sequence A; adopting a surface mass load redistribution model to calculate a vertical direction displacement time series of the IGS reference station caused by environmental loads, i.e., Sequence B; adopting a GPS precise data processing model to obtain a coordinate time sequence of the IGS reference station, i.e., Sequence C; deducting Sequence B from Sequence C to obtain Sequence C-B; deducting Sequence A from Sequence C-B to obtain Sequence C-B-A; and based on the Sequence C-B and Sequence C-B-A, proposing that numerical value indexes are utilized to qualify the influence of the thermal expansion effect on the GPS coordinate time series. The method for accurately quantifying the influence of the thermal expansion effect on the GPS coordinate time series can obtain actual motion in the vertical direction of the IGS reference station caused by temperature variation, and adopts the numerical value indexes to accurately quantify the influence of the thermal expansion effect.

The invention discloses a GPS coordinate time sequence discontinuity complementing method based on a common-mode error, and the method comprises the steps: S1, selecting a medium- and small-scale GPS network, and selecting a plurality of continuity measurement stations from the continuity measurement stations in the medium- and small-scale GPS network; S2, obtaining the residual error coordinate time sequence of the continuity measurement stations according to the coordinate time sequence observation data of the continuity measurement stations; S3, selecting any one measurement station from the plurality of selected continuity measurement stations as a reference base station, and determining the common epoch of the reference station and the common continuity measurement stations in the medium- and small-scale GPS network; S4, obtaining the common-mode error that all common continuity measurement stations in the medium- and small-scale GPS network jointly act on the reference station; S5, complementing the GPS coordinate time sequence of a discontinuity measurement station in the medium- and small-scale GPS network through the common-mode error. According to the invention, the method achieves the complementing of the discontinuous data through employing the similarity of the continuous data residual error time sequence of the spatial distribution in the medium- and small-scale range, and improves the derivative quality based on the GPS coordinate time sequence.

The invention discloses a quantitative method for influences on a GPS coordinate time series by a higher-order item ionospheric delay. The method comprises the steps of collecting original observation data of a GPS base station; obtaining a GPS coordinate time series considering only the first order term of the ionospheric delay based on the historical observation data and recording the GPS coordinate series as sequence A; calculating the GPS coordinate time series corrected by the ionospheric high order term based on the historical observation data and recording the series as sequence B; aligning the series A and the series B in a time domain and subtracting the series A and the series B to obtain a high-order term ionospheric delay influence time series of the GPS base station and recording the series as sequence C; and separately subjecting the sequence A, sequence B and sequence C to noise analysis to obtain the observation station speed, noise characteristics and seasonal information corresponding to each sequence so as to quantify the influence of the high-order term ionospheric delay. The quantitative method of the invention can quantitatively determine the influence of the high-order ionospheric delay on the observation station coordinate time series, and can better explain the non-linear variation source presented in the GPS coordinate time series.

The invention provides a GNSS observation station nonlinear motion modeling method and device, and belongs to the technical field of global positioning navigation systems. The method comprises the steps of obtaining an original coordinate time sequence of a GNSS observation station; performing wavelet decomposition and reconstruction on the original coordinate time sequence to obtain a low-frequency part and a multi-layer high-frequency part; performing singular spectrum decomposition and reconstruction on the low-frequency part and each layer of high-frequency part; synthesizing the low-frequency part after singular spectrum decomposition and reconstruction and the high-frequency part of each layer to obtain a fitting sequence of an original coordinate time sequence; and modeling the fitting sequence. The method comprises the following steps: an original coordinate time sequence is decomposed into relatively single and smooth low-frequency parts and high-frequency parts of all layersby utilizing wavelet decomposition and reconstruction; and then singular spectrum decomposition and reconstruction are performed on each part, so that the probability that part of periodic items suchas seasonal periodic items and monthly periodic items are rejected as noise is reduced to a certain extent, and the modeling precision is improved.

The invention provides a test platform dynamic performance evaluation method with input and output signal waveform comparison, belonging to the field of dynamic performance testing. The method can be applied to the fields of mechanical engineering, aerospace and the like to evaluate the dynamic performance of a test platform. An experimental device is formed by a signal generator, a power amplifier, a rubber rope, a vibration exciter, a jack, an impedance head, a test bench, a test platform, a charge amplifier, a data acquisition card and a computer. The evaluation method comprises the following steps that the ratio of an output waveform vertical coordinate absolute value to a horizontal coordinate time integral and an input waveform vertical coordinate absolute value to the horizontal coordinate time integral in the same cycle are compared, the dynamic performance of the test platform is good if the ratio is close to 1. The test device is simple, the operation is easy, the evaluation method is intuitive and easy to understand, the dynamic performance of the test platform can be quickly determined, and the method has broad application space.

The invention discloses a test bed for the braking performance of an automobile/a train. The test bed is characterized in that a signal acquisition part of a sensor is composed of a left detection unit group and a right detection unit group which are formed by linearly arranging a plurality of detection units, and the left detection unit group and the right detection unit group are in symmetric distribution. A braking detection unit comprises a braking sand-adhering plate; the braking sand-adhering plates on the left detection unit group and the right detection unit group are independent, with a distance of 8 mm; each braking detection unit and each weighing detection unit work independently to respectively realize acquisition of braking data and weight data and are independently connected with a signal acquisition processing device; and the signal acquisition processing device is electrically connected with a data processing system. The automobile/train is subjected to multi-axial overall online detection, so that the braking time sequence of the vehicle, the dynamic braking power of the entire vehicle, the poor braking process, the coordinate time and the like of the entire vehicle can be detected in one braking process, therefore, the labor intensity of detection is alleviated, the detection efficiency is improved, and the braking performance of the vehicle can be reflected more truly.