Nonlinearity is a prominent limitation to the calibration performance for two-axis fluxgate sensors. In this paper, a novel nonlinear calibration algorithm taking into account the nonlinearity of errors is proposed. I...
详细信息
Nonlinearity is a prominent limitation to the calibration performance for two-axis fluxgate sensors. In this paper, a novel nonlinear calibration algorithm taking into account the nonlinearity of errors is proposed. In order to establish the nonlinear calibration model, the combined effort of all time-invariant errors is analyzed in detail, and then harmonic decomposition method is utilized to estimate the compensation coefficients. Meanwhile, the proposed nonlinear calibration algorithm is validated and compared with a classical calibration algorithm by experiments. The experimental results show that, after the nonlinear calibration, the maximum deviation of magnetic field magnitude is decreased from 1302 nT to 30 nT, which is smaller than 81 nT after the classical calibration. Furthermore, for the two-axis fluxgate sensor used as magnetic compass, the maximum error of heading is corrected from 1.86 degrees to 0.07 degrees, which is approximately 11% in contrast with 0.62 degrees after the classical calibration. The results suggest an effective way to improve the calibration performance of two-axis fluxgate sensors.
This paper presents a Newton iteration-based calibration algorithm for pipelined analog-to-digital converter (ADC). The proposed calibration algorithm equalizes the errors induced by incomplete settling of operational...
详细信息
ISBN:
(纸本)9781538608432
This paper presents a Newton iteration-based calibration algorithm for pipelined analog-to-digital converter (ADC). The proposed calibration algorithm equalizes the errors induced by incomplete settling of operational amplifier (op-amp) to the inter-stage gain errors. To compensate the inter-stage gain errors, a significant calibration parameter P3 is introduced, whose optimal solution is searched through Newton iteration method. With this parameter which is estimated through Newton iteration method, inter-stage gain errors will be compensated, and the digital output calibrated of ADC can be obtained. The presented calibration algorithm not only improves the ADC performance, but also is helpful to reduce the design difficulty of analog circuit by tolerating the incomplete settling errors caused by op-amp with low performance. A 14-bit 100MS/s pipelined ADC model with this calibration algorithm is built and simulated on MATLAB. Simulation results show this calibration algorithm improves SFDR from 55.08dB to 105.43dB, SNDR from 45.69dB to 82.85dB and ENOB from 7.29 to 13.47 at Nyquist input frequencies.
In this paper, we propose a pixel averaging current calibration algorithm for reducing fixed pattern noise due to the deviation of bolometer resistance. To reduce fixed pattern noise (FPN), averaging current calibrati...
详细信息
ISBN:
(纸本)9781510609204
In this paper, we propose a pixel averaging current calibration algorithm for reducing fixed pattern noise due to the deviation of bolometer resistance. To reduce fixed pattern noise (FPN), averaging current calibration algorithm by which output current of each bolometer reference pixel is averaged by the averaging current calibration is suggested. The principle of algorithm is that average dark current of reference pixel array is subtracted by a dark current of each active pixel array. After that, the current difference with information of pixel deviation is converted to voltage signal through signal processing. To control the current difference of pixel deviation, a proper calibration current is required. Through this calibration algorithm, nano-ampere order dark currents with small deviations can be obtained. Sensor signal processing is based on a pipeline technique which results in parallel processing leading to very high operation. The proposed calibration algorithm has been implemented by a chip which is consisted of a bolometer active pixel array, a bolometer reference pixel array, average current generators, line memories, buffer memories, current-to-voltage converters (IVCs), a digital-to-analog converters (DACs), and analog-to-digital converters (ADCs). Proposed bolometer-resistor pixel array and readout circuit has been simulated and fabricated by 0.35 mu m standard CMOS process.
In this paper, a novel calibration algorithm based on real-valued time-delay neural network (RVTDNN) is proposed for the multiport receiver to recover I/Q signals from the received modulated signals, especially from w...
详细信息
In this paper, a novel calibration algorithm based on real-valued time-delay neural network (RVTDNN) is proposed for the multiport receiver to recover I/Q signals from the received modulated signals, especially from wideband signals. All the system impairments, including the nonideal six-port correlator, the nonlinearity of the diodes, and the memory effects under the excitation of the wideband signals, are taken into consideration. The RVTDNN, which has three layers, consists of four inputs and two outputs (in-phase and quadrature signals), and its parameters (biases and weights) are all real-valued and are determined by the backpropagation algorithm. Finally, the proposed calibration method is validated by a 2-18-GHz six-port receiver under 3G and 4G signals. The performance of the error vector magnitude between the transmitted signals and received signals is always less than 1.8%, which validates the correctness of the proposed model.
According to the principle of electronic compass, we analyze the error of the E-compass and propose a calibration scheme in view of magnetic deviation, which is based on the self-designed tri-axial magnetometer system...
详细信息
ISBN:
(纸本)9781509027323
According to the principle of electronic compass, we analyze the error of the E-compass and propose a calibration scheme in view of magnetic deviation, which is based on the self-designed tri-axial magnetometer system. The hardware is made by hi-axial magnetometer and hi-axial accelerometer. Considering the magnetic interference of the external environment will affect the magnetic deviation, we worked out a compensation method based on ellipsoid fitting. The experiment results showed the sitnplicity and efficiency of the algorithm. The compass deviation fell from 15 degree to within ldegree. And it can maintain high accuracy even under large magnetic dip.
The calibration path of system-level calibration directly affects the incentive effect of the error term and thus the calibration accuracy. Currently, the planning of system-level calibration paths is predominantly de...
详细信息
The calibration path of system-level calibration directly affects the incentive effect of the error term and thus the calibration accuracy. Currently, the planning of system-level calibration paths is predominantly designed based on personal experience, resulting in insufficient incentive for error terms, low calibration accuracy, and long calibration times. Therefore, this study proposes a system-level calibration optimal path planning method based on an improved Dijkstra's algorithm. First, the system-level calibration optimal path planning problem was modeled as a multi-fork regular root tree model, and the adaptability of Dijkstra's algorithm was improved. Second, a 30-dimensional Kalman filter model was designed for system-level calibration. Then, simulation experiments were conducted, and the results demonstrated that the calibration accuracy of the error term reached 90% within 330 s. Finally, a Micro-Electro-Mechanical system (MEMS) inertial sensor, model PA-IMU488B, was used for experimental verification, and the results were compared with the discrete calibration results. The results indicate that the bias and scale factor errors of the MEMS inertial sensor reached the target accuracy within 5 min. The optimal path planning method for system-level calibration proposed in this study is not dependent on a high-precision turntable, is applicable to sensors of different accuracies, and decreases calibration time while ensuring calibration accuracy.
A computer-based system and algorithm for calibration of True RMS ammeters is proposed. An approach was used to calibrate True RMS ammeters by using standard square waveform signals as an alternative of the classical ...
详细信息
ISBN:
(数字)9781665485692
ISBN:
(纸本)9781665485692
A computer-based system and algorithm for calibration of True RMS ammeters is proposed. An approach was used to calibrate True RMS ammeters by using standard square waveform signals as an alternative of the classical used harmonic signal. Based on a developed algorithm, the calibration system performs the sequence of steps for controlling the Metrix CX1651 standard calibrator and the calibrated True RMS ammeter PICOTEST M3500A. For this purpose, standard True RMS current values from the calibrator are set, multiple measurements are made at the calibration point, measured results from the ammeter are derived and processed to receive an estimate of the actual value of the measured current values and an estimate of the expanded uncertainty at the calibration point. Results of calibrations using classic sinusoidal and square waveform signals were received, and the two approaches were compared and analyzed, which evidenced their equivalence.
作者：
Wu, LeiXu, YonghongLi, RuizhiNorthwest A&F Univ
Key Lab Agr Soil & Water Engn Arid & Semiarid Area Minist Educ Yangling 712100 Shaanxi Peoples R China Northwest A&F Univ
State Key Lab Soil Eros & Dryland Farming Loess Pl Yangling Shaanxi Peoples R China Northwest A&F Univ
Coll Water Resources & Architectural Engn Yangling Shaanxi Peoples R China Minist Water Resources
Xifeng Hydrol & Water Resources Survey Bur Yellow Qingyang Gansu Peoples R China
Low resolution of input data and equifinality in model calibration can lead to inaccuracy and insufficient reflection of spatial differences, thereby increasing model errors. However, the impact of input data accuracy...
详细信息
Low resolution of input data and equifinality in model calibration can lead to inaccuracy and insufficient reflection of spatial differences, thereby increasing model errors. However, the impact of input data accuracy, catchment threshold area, and calibration algorithm on model uncertainty reduction has not yet been well understood. The sequential uncertainty fitting version 2 (SUFI-2) that is linked with the Soil and Water Assessment Tool (SWAT) in the package called SWAT calibration Uncertainty Programs (SWAT-CUP) was introduced to quantify the effects of different input data resolutions on parameter sensitivity and model uncertainty in the Jinghe River watershed, and the effects of different sub-basin delineations and other two calibration algorithms on model uncertainty were also comparatively analysed. (i) USLE_C, EPCO, ALPHA_BNK, and CN2 are the most sensitive parameters among all SWAT projects. When the change of digital elevation model (DEM) resolution is small, the sensitivity of parameters does not change obviously. When the DEM resolution changes significantly, BIOMIX, LAT_SED, USLE_K, and CH_N1 become highly sensitive parameters by replacing OV_N, SMTMP, SURLAG, and USLE_P. However, the change in land use resolution has little impact on parameter sensitivity, with only a slight change in the sensitivity ranking of specific parameters. (ii) Model uncertainty responded to changes in the resolution of DEM more than land use. Most of the runoff simulations had smaller uncertainties (P factor, R factor, percentage of bias [PBIAS]) than sediment. High resolution DEM data reduced model uncertainty, but the models with 2000 m DEM resolution also achieved small uncertainty. Small catchment threshold area leads to high uncertainty of the model, and large catchment threshold areas decrease the model uncertainty. The model has relatively good simulation effects in runoff and sediment when the catchment threshold area was 2000 km(2). (iii) The SWAT model has differe
The possibility for calibrating Power Quality Analyzer by harmonics is presented by using a reference square waveform signal. Based on the calibration model, a control algorithm is synthesized of the calibration measu...
详细信息
ISBN:
(纸本)9781665445375
The possibility for calibrating Power Quality Analyzer by harmonics is presented by using a reference square waveform signal. Based on the calibration model, a control algorithm is synthesized of the calibration measurement procedures and the processing of the uncertainty of the calibration results. Results from the calibration of the Fluke 435 analyzer with the Metrix CX1651 calibrator on voltage and current harmonics are presented, which confirm the possibilities of using the reference square waveform signal.
The approach to calibrate the coefficient of total harmonic distortion of power quality analyzers using reference standard non-harmonic waveform signals, instead of the traditionally used set of harmonic signals is co...
详细信息
ISBN:
(纸本)9781665445375
The approach to calibrate the coefficient of total harmonic distortion of power quality analyzers using reference standard non-harmonic waveform signals, instead of the traditionally used set of harmonic signals is considered in [1]. Using a reference calibrator, square, triangular, saw-shaped signals and a truncated sine wave signal are generated in series, which provide setting of appropriate reference values of the total harmonic distortions for which the analyzer is calibrated. In the present work, a computer-based automation system and algorithm for calibration of Power Quality Analyzer are proposed by THD. The algorithm performs the sequence of operations for control of the reference calibrator and the calibrated analyzer, setting reference values of THD of the voltage/current from the calibrator, performing multiple measurements at the calibration point, measured results are extracted from the analyzer and their processing and an estimate of the actual value of the measured THD values and an estimate of the extended uncertainty is obtained at the analyzer calibration point.
暂无评论