316 results about "Error coefficient" patented technology

A method and apparatus comprises providing a vector network analyzer having at least two measurement ports and presenting a high reflect calibration standard, a line calibration standard, a source terminated thru calibration standard, and a locally terminated through calibration standard at each measurement port or pair of measurement ports. Forward and reverse reflection tracking is calculated based upon a boundary condition wherein an argument of the reflection tracking coefficients is zero at DC. The DUT is measured and the measurement is corrected for systematic errors based upon the error coefficients.

An accurate calibration method of micro inertia measuring unit by decoupling erection error angle (EEA)with scale factor includes setting up MIMU integral error model and separating couple between EEA of accelerometer and gyroscope and scale factor ,using position error canceling method to calculate out and to separate out scale factor and EEA of accelerometer as well as using least square method and iteration method to calculate out EEA of gyroscope and its relative error items in 10 position static calibration test and in 3 direction positive and negative rate test ,then using interpolation method to calculate out scale factor of gyroscope .

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops. Also, other advantages are provided such as the elimination of a error floor present in prior art serially-concatenated codes. That allows the present invention to achieve much higher performance at lower error rates such as are needed in optical communication systems.

Global Navigation Satellite System (GNSS) pseudorange measurements are compensated for receiver hardware and directionally dependent antenna errors to obtain desired accuracies for high precision GNSS positioning applications using a multiple element controlled reception pattern antenna (CRPA). Pseudorange errors are calibrated and stored in a sky map by azimuth, elevation, radio frequency (RF) channel, and frequency. Corrections are applied in real time to each pseudorange measurement by applying a combination of the stored errors. The coefficients of the errors in the combination are computed as a function of steering vectors and CRPA filter weights. This implements a generalized pseudorange correction able to compensate a GNSS CRPA sensor for channel dependent errors such as group delay for both the case of uniform weights for all frequencies and the more complex case of frequency-dependent weights.

The invention relates to a method for positioning a mobile node of a wireless sensor network based on a crossed particle swarm. After the deployment of anchor nodes is finished, the mobile node enters a greenhouse area, and broadcasts and sends a positioning request to all anchor nodes in a network; the mobile node receives the broadcast information of normal anchor nodes, measurement distance between the mobile node and the corresponding anchor node is obtained by calculation, and the measurement distance is corrected by using error coefficients of each anchor node; the mobile node substitutes the information of the normal anchor nodes and the corrected distance into a crossed particle swarm positioning algorithm for optimal calculation; and the algorithm outputs a cluster optimal position as an estimated coordinate of the mobile node. The coordinate of the mobile node is accurately estimated. The method is high in convergence speed, low in calculation complexity, perfect, and high in positioning performance.

The invention discloses a method for marking IMU each item error coefficient precisely, which comprises the following steps: marking the gyroscopic scale factor and gyroscopic installment error in the IMU error model through dynamic calibration experiment; substituting the error value in the symmetrical 24 position static calibration experiment of adjacent position; adapting the symmetrical position error cancellation law to mark IMU residual each item error coefficient within gyroscopic constant drift, error item of gyroscope and acceleration, accelerometer constant bias, accelerometer marking factor and accelerometer fixation error.

The invention relates to a quick calibration method for an inertial measurement unit (IMU). According to the method, a user holds and rotates the IMU to move in all directions without any external equipment, so that twelve error coefficients including gyro biases, gyro scale factors, accelerometer biases and accelerometer scale factors can be accurately calibrated in a short time. The quick calibration method for the IMU is characterized by being free of hardware cost, high in efficiency and simple and easy to implement, and can ensure certain calibration precision. Thus, the quick calibration method is especially suitable for in-situ quick calibration for the medium- and low-grade IMUs, thereby effectively solving the problem of environmental sensitivity of the error coefficients of the mechanical IMU, and promoting popularization and application of MEMS (micro-electro mechanical systems) inertial devices.

The invention discloses a triaxial MEMS gyroscope rotation integral calibration method based on a uniaxial turntable. According to the invention, first, a triaxial MEMS gyroscope error model is established; the triaxial MEMS gyroscope is fixed on the uniaxial turntable; MEMS gyroscope six-position rotary calibration is carried out; test data and sampling time of 12 times of rotation of the MEMS gyroscope at the 6 positions are tested and recorded; through the 12 times of rotation of the MEMS gyroscope at the 6 positions, a MEMS gyroscope error model is simplified, and an error model after gyroscope rotation is obtained; integral calculations are carried out upon two sides of the equation of the error model after gyroscope rotation, an error equation set is established, and MEMS gyroscope error coefficient is obtained by calculation. With the method provided by the invention, calibration precision is ensured; and fixed zero bias, scale factor, cross-coupling error coefficient, and acceleration sensitivity coefficient of the MEMS gyroscope can be solved rapidly, such that calibration efficiency is improved.

The invention discloses a method of a micro combined multi-sensor navigation system with quick outfield calibration, and the micro combined multi-sensor navigation system of the method comprises a two-dimensional obliquity sensor, a micro magnetic compass, three silicon MEMS gyros and three silicon MEMS accelerometers. In order to improve the use precision of the micro combined multi-sensor navigation system, the method of the invention discloses that the instant quick outfield calibration is implemented on the micro combined multi-sensor navigation system before use; wherein, the two-dimensional obliquity sensor provides a calibration horizontal benchmark, the micro magnetic compass provides a calibration azimuth benchmark, the three silicon MEMS gyros and the three silicon MEMS accelerometers measure the output of angular velocity and accelerated velocity, and seven core error coefficients of the micro combined multi-sensor navigation system are calibrated in a data post-processing. The method of the micro combined multi-sensor navigation system with quick outfield calibration is simple, convenient and efficient, overcomes the defect that the repetitiveness of each starting of the micro combined multi-sensor navigation system is bad, directly improves the precision of each use, and avoids the inconvenience that is caused by the dependence of traditional calibration methods on special high-precision laboratory equipment.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. Constrained interleaving can be summarized in that it: 1) uses an outer code that is a block code or a non-recursive convolutional code, and as such, there are multiple codewords present in the constrained interleaver, 2) selects a desired MHD, 3) selects an interleaver size and a set of predefined interleaver constraints to prevent undesired (low-distance) error events so as to achieve the desired MHD, and 4) performs uniform interleaving among the allowable (non-constrained) positions, to thereby maximize or otherwise improve the interleaver gain subject to the constraints imposed to maintain the desired MHD.

A pattern inspection apparatus includes a first unit configured to acquire an optical image of a target workpiece to be inspected, a second unit configured to generate a reference image to be compared, a third unit configured, by using a mathematical model in which a parallel shift amount, an expansion and contraction error coefficient, a rotation error coefficient, a gray-level offset and an image transmission loss ratio are parameters, to calculate each of the parameters by a least-squares method, a forth unit configured to generate a corrected image by shifting a position of the reference image by a displacement amount, based on the each of the parameters, and a fifth unit configured to compare the corrected image with the optical image.

A method is provided for reducing quadratic phase errors in synthetic aperture radar signals from a plurality of range lines where each range line includes a plurality of azimuth positions. The method includes receiving a plurality of slow-time samples representing radar signals for a plurality of azimuth positions for a plurality of range lines. A plurality of corrected samples and an initial quadratic phase error coefficient are identified based upon the slow-time samples. The corrected samples are processed according to a superresolution signal processing technique to thereby obtain a plurality of estimated Doppler frequencies for a plurality of point scatterers at each range line, after which a true signal for each range line is reconstructed based upon the plurality of estimated Doppler frequencies. A correction to the initial quadratic phase error coefficient is then obtained based upon the corrected samples, the true signals and the initial quadratic phase error coefficient.

Provided is an intelligent ammeter reliability prediction correction model building method, comprising the steps of: (1) according to a component stress method, building an intelligent ammeter reliability prediction model; (2) according to field data, building an intelligent ammeter reliability prediction model; (3) comparing the reliability prediction model and the filed data to obtain an intelligent ammeter work failure rate; (4) calculating an error coefficient, i.e., a correction factor; and (5) building a reliability prediction correction model.

The invention provides a vehicle-mounted integrated navigation method of resisting to failure of a global positioning system, and relates to a GPS-failure-resisting integrated navigation method suitable for a vehicle-mounted low-cost integrated navigation system. The vehicle-mounted integrated navigation method of resisting to failure of the GPS comprises the following steps that firstly, relative time delay of measurement data of different types of sensors is estimated with the dynamic convolution correlation method, and output data of three types of sensors which are the GPS, a gyroscope and the speed sensor are corrected according to the relative time delay; secondly, outliers of original data of the three types of sensors are removed through an outlier-removing innovation orthogonality sliding window average filter, and the discrete degree of the data is reduced; thirdly, error coefficients of the gyroscope and the speed sensor are estimated online in real time in the effective status of the GPS, and compensation for the error coefficients is conducted; fourthly, when failure of the GPS occurs, the recursive algorithm is started and the position information and course information are given. According to the vehicle-mounted integrated navigation method of resisting to failure of the GPS, the problem that error drifting of the vehicle-mounted low-cost gyroscope and the speed sensor is rapid is solved, position and course accuracy is improved obviously, and the vehicle-mounted integrated navigation method of resisting to failure of the GPS can be used for various vehicle-mounted navigation systems comprising GPSs, gyroscopes and speed sensors.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops. Also, other advantages are provided such as the elimination of a error floor present in prior art serially-concatenated codes. That allows the present invention to achieve much higher performance at lower error rates such as are needed in optical communication systems.

Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. Constrained interleaving can be summarized in that it: 1) uses an outer code that is a block code or a non-recursive convolutional code, and as such, there are multiple codewords present in the constrained interleaver, 2) selects a desired MHD, 3) selects an interleaver size and a set of predefined interleaver constraints to prevent undesired (low-distance) error events so as to achieve the desired MHD, and 4) performs uniform interleaving among the allowable (non-constrained) positions, to thereby maximize or otherwise improve the interleaver gain subject to the constraints imposed to maintain the desired MHD.

A method and apparatus for calibrating a measurement path of 2N measurement ports comprises presenting a high reflect calibration standard at each measurement port and measuring a reflection characteristic for each measurement port, presenting a line calibration standard and a through calibration standard between each one of N direct pairs of the measurement ports and measuring forward and reverse reflection and transmission responses and calculating a load match error coefficient for each measurement port, and presenting only the through calibration standard between indirect pairs of measurement ports and calculating the forward and reverse transmission tracking for each indirect pairs of measurement ports.

The invention provides a method for fast calibration of medium-and-low-precision optical fiber inertia units and belongs to the technical field of inertia measurement. The method comprises the steps of controlling a turntable rotation inertia measurement unit according to a designed calibration path, and measuring output data of the east-north-up orientation, down-north-east orientation, down-east-south orientation and east-up-south orientation and output data during orientation conversion in sequence; then calibrating the scale factors and null biases of a fiber-optic gyroscope and an accelerometer according to mathematic models of the fiber-optic gyroscope and the accelerometer. By the adoption of the method, the null biases and scale factors of the fiber-optic gyroscope and accelerometer, twelve error coefficients in total, can be calibrated accurately within a short period of time, calibration efficiency is high, and calibration is easy. The method is suitable for fast calibration of the medium-and-low-precision optical fiber inertia units produced in bulk, and can promote the application and popularization of other medium-and-low-precision inertial devices.

The present invention discloses an entropy decoding method used for the decoding of a video predictive residual coefficient. A decoding end reads the auxiliary information of the current macroblock, determines the types of the macroblock and image blocks and orderly executes all the nonzero image blocks of the current macroblock; according to the types of the macroblock and the current image block, a code table type used to decode the current image block is selected, the code table type of the current image block corresponds to multiple different code tables; the code tables are switched in turn in order to decode the Exp-Golomb code of the current image block and obtain each (level, run) coefficient pair of the current image block. The present invention also discloses an entropy decoding device used for the decoding of the video predictive residual coefficient, which includes a code stream receiving unit, a code table providing unit and a decoding unit. The method and the device disclosed by the present invention sufficiently consider the context environment and the statistic regularity of a video block residual coefficient, do not affect the realization of the complexity of computation and increase the effeciency of encoding and decoding.