46 results about "Allan variance" patented technology

A measuring device includes a pair of sensors, an actuator, a noise extraction unit and a low frequency noise (LFN) estimator. The sensors each generate with sample time Ts a sense signal indicating a value of a component of a vectorial physical quantity. The sensors have an Allan variance curve with a minimum value for a first integration time T1. The curve has a first and second tangent line being tangent at integration time 0, and integration time T1 respectively. The tangent lines intersect each other at an intersection point for a second integration time T2. The estimator having an effective integration time Teff determined by, Ts, T1 and T2, generates an estimated noise signal indicative for the estimated value of the noise component from the difference signal and from information about the relative rotation between the sensors.

The invention claims for protection of an MEMS accelerometer error compensation method based on LMS adaptive filtering and gradient descent. An MEMS accelerometer error compensation model with a measured value as an input and a true value as an output is established; random noises in actually measured data of the MEMS accelerometer at six positions are analyzed and processed by using an Allan variance and an LMS adaptive filtering algorithm; model parameters are trained by using all processed measurement data as samples; parameter prior values are calculated by using least squares to obtain aninitial value of batch gradient descent; training is carried out to obtain optimal fitting of samples to true model parameters; and error compensation is carried out on the MEMS accelerometer by using the model. The experiments show that the mean value error of output values of the accelerometer is reduced by two magnitude orders after error compensation and the standard deviation is reduced by one order of magnitude. The MEMS accelerometer error compensation method can be applied to high-precision calibration of MEMS accelerometers in the micro inertial measurement unit (MIMU), so that the measurement accuracy and output stability of the accelerometer are improved.

A Modeling, Design, Analysis, Simulation, and Evaluation (MDASE) aspects of gyrocompassing in relation to Far-Target Location (FTL) systems include a Gyrocompass Modeling and Simulation System (GMSS). The GMSS has four major components: the 6 degree-of-freedom (6DOF) Motion Simulator, the IMU Sensor Simulator, the Gyrocompass System and Calibration Process Simulator, and the Gyrocompass System Evaluation and Analysis Module. The modular architecture of GMSS makes it very flexible for programming, testing, and system maintenance. The realization of the GMSS can be based on any computer platforms for the GMSS software is written in high level language and is portable. The stochastic signal analysis and sensor testing and modeling tools comprise a suite of generic statistical analysis software, including Allan Variance and power spectral density (PSD) analysis tools, which are available to every GMSS module and greatly enhanced the system functionality.

The invention provides a DMTD measuring method and measuring system. According to the DMTD measuring method and measuring system, an uninterrupted common source signal is selected, two counters are used for acquiring the time counting values of the common source signal respectively in real time, when the rising edges of reference signals and the rising edges of detected signals come respectively, the time counting values of the current two counters are acquired respectively, the number of the rising edges of the reference signals and the number of the rising edges of the detected signals align at each other, the two time counting values corresponding to the aligning numbers are subtracted to obtain an accurate time difference value, and other frequency differences, phase differences, Allan variances and the like can be calculated according to the accurate time difference value. The common source signal mode is used, the problem that a traditional exclusive-OR gate mode can not conduct accurate measurement in times of edge overlapping or when two edge time differences are smaller than hardware response time is solved, and the cycle fuzzy phenomenon which commonly exists in the DMTD measuring process is avoided. In brief, the DMTD measuring method and measuring system can achieve quick, accurate, real-time and unlimited measuring with low cost.

The invention discloses an automatic telescope pointing correction method based on ALLAN variance analysis under a motion platform. The positioning precision of a telescope is relevant to the motion precision of a mechanical system and is affected by mechanical and electrical equipment and software control algorithms. With the development of electronic techniques, mechanical errors in processing and assembling are main factors affecting the positioning precision. The mechanical errors mainly include part machining errors, bearing errors, telescope assembly errors, structural deformation and the like. A photoelectric tracking system installed on the motion platform is affected by carrier motions, vibrations and the like. In addition, due to the use of inertial devices, alignment errors, drift errors of inertial sensitive devices and the like are introduced. Base on the basic principle of telescope pointing and pointing error source analysis, an automatic pointing correction model basedon ALLAN variance analysis under the motion platform is established, the correction precision and model stability are improved, and automatic pointing correction is also achieved.

A method for determining the measurement precision of a formation evaluation tool in a borehole comprises: a) conveying the formation evaluation tool into the borehole, b) using the formation evaluation tool to make measurements, and c) analyzing the measurements using mean squared difference stability statistics to generate an output indicative of measurement precision. Step c) may comprise using an Allan variance to assess the measurements taken in step b). The method may further include deriving an optimum logging speed from the analysis performed in step c), which may occur at the lowest value of the Allan variance.

The invention provides a DMTD measuring method and measuring system. According to the DMTD measuring method and measuring system, an uninterrupted common source signal is selected, two counters are used for acquiring the time counting values of the common source signal respectively in real time, when the rising edges of reference signals and the rising edges of detected signals come respectively, the time counting values of the current two counters are acquired respectively, the number of the rising edges of the reference signals and the number of the rising edges of the detected signals align at each other, the two time counting values corresponding to the aligning numbers are subtracted to obtain an accurate time difference value, and other frequency differences, phase differences, Allan variances and the like can be calculated according to the accurate time difference value. The common source signal mode is used, the problem that a traditional exclusive-OR gate mode can not conduct accurate measurement in times of edge overlapping or when two edge time differences are smaller than hardware response time is solved, and the cycle fuzzy phenomenon which commonly exists in the DMTD measuring process is avoided. In brief, the DMTD measuring method and measuring system can achieve quick, accurate, real-time and unlimited measuring with low cost.

A random error characteristic analysis method of optical fiber current transformer based on total variance, the method first collects the current signal of optical fiber current transformer through serial output, and obtains the observation data; Carry out zero-mean, trend item and standardization processing; test the stationarity, periodicity and normality of the processed data to obtain a stable, normal, and zero-mean data sequence; use the total variance method to perform variance processing on the data sequence; finally The logarithmic curve fitting of the total variance and the correlation time (τ) is carried out by using the square sum of the variance of the random error source, and five random error coefficients in the current information of the optical fiber current transformer are extracted. The invention can analyze the random error characteristics of the optical fiber current transformer more accurately, effectively solve the shortcoming of the traditional Allan variance method that the estimated value fluctuates violently, and provide guidance for the performance design of the optical fiber current transformer and compensation of random errors.