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[IEEE 2019 4th International Conference on Power and Renewable Energy (ICPRE) - Chengdu, China (2019.9.21-2019.9.23)] 2019 4th International Conference on Power and Renewable Energy (ICPRE) - Research on Two-Stage Three-Phase Photovoltaic Grid-Connected System with MPPT
摘要： Several state-of-the-art monitoring and control systems, such as dc motor controllers, power line monitoring and protection systems, instrumentation systems, and battery monitors, require direct digitization of high-voltage (HV) input signals. Analog-to-digital converters (ADCs) that can digitize HV signals require high linearity and low-voltage coefficient capacitors. A built-in self-calibration and digital-trim algorithm correcting static mismatches in capacitive digital-to-analog converter (DAC) used in successive approximation register analog-to-digital converters (SAR ADCs) is proposed. The algorithm uses a dynamic error correction (DEC) capacitor to cancel the static errors occurring in each capacitor of the array as the first step upon power-up and eliminates the need for an extra calibration DAC. Self-trimming is performed digitally during normal ADC operation. The algorithm is implemented on a 14-bit HV input range SAR ADC with integrated DEC capacitors. The IC is fabricated in 0.6-μm HV-compliant CMOS process, accepting up to 24Vpp differential input signal. The proposed approach achieves 73.32-dB signal-to-noise and distortion ratio, which is an improvement of 12.03 dB after self-calibration at 400-kS/s sampling rate, consuming 90 mW from a ±15 V supply. The calibration circuitry occupies 28% of the capacitor DAC and consumes <15 mW during operation. Measurement results show that this algorithm reduces integral nonlinearity from as high as 7 LSBs down to 1 LSB, and it works even in the presence of larger mismatches exceeding 260 LSBs. Similarly, it reduces differential nonlinearity errors from 10 LSBs down to 1 LSB. The ADC occupies an active area of 9.76 mm2.
关键词： self-calibration,digital trimming,Analog-to-digital (A/D) conversion,mismatch correction
更新于2025-09-19 17:13:59
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Camera Calibration: An Overview of Concept, Methods and Equations
摘要： Camera calibration is favored as an important issue in photogrammetry and computer vision literatures. The importance of this issue can be due to two reasons: firstly, every recently camera should be calibrated before being used to correct its lens distortion and interior orientation elements. In addition, it is a main preprocessing step at many vision applications. This paper aims to provide an overview of concept, objective, methods and mathematical equations for camera calibration.
关键词： Self–Calibration,Photogrammetry,Interior Orientation Elements,Camera Calibration,Lens Distortion,Exterior Orientation Elements,Computer Vision
更新于2025-09-10 09:29:36
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[IEEE 2018 10th International Conference on Communication Software and Networks (ICCSN) - Chengdu (2018.7.6-2018.7.9)] 2018 10th International Conference on Communication Software and Networks (ICCSN) - An Amplitude-phase Measurement Method of Phased Array Antenna Based on Self-Calibration RF Channel
摘要： Caused by the amplitude-phase error of phased array antenna, the pattern performance unable to meet the optimum design results. Thus, the phase and amplitude of phased array antenna should be measured and calibrated. An measurement method of phased array antenna based on self-calibration RF channel is presented in this paper. First of all, the initial amplitude-phase is measured by self-calibration RF channel. Secondly, the modified value related to self-calibration RF channel is achieved by use of Mid-field receiving power calculation method. Finally, the actual amplitude and phase weighting factor of phased array antenna is obtained, based on calibration of the initial amplitude-phase with the modified value. The comparison of planar near-field measured results show that the proposed method is feasible and efficient.
关键词： amplitude-phase measurement method,self-calibration,phased array antenna
更新于2025-09-10 09:29:36
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Simultaneous All-Parameters Calibration and Assessment of a Stereo Camera Pair Using a Scale Bar
摘要： Highly accurate and easy-to-operate calibration (to determine the interior and distortion parameters) and orientation (to determine the exterior parameters) methods for cameras in large volume is a very important topic for expanding the application scope of 3D vision and photogrammetry techniques. This paper proposes a method for simultaneously calibrating, orienting and assessing multi-camera 3D measurement systems in large measurement volume scenarios. The primary idea is building 3D point and length arrays by moving a scale bar in the measurement volume and then conducting a self-calibrating bundle adjustment that involves all the image points and lengths of both cameras. Relative exterior parameters between the camera pair are estimated by the five point relative orientation method. The interior, distortion parameters of each camera and the relative exterior parameters are optimized through bundle adjustment of the network geometry that is strengthened through applying the distance constraints. This method provides both internal precision and external accuracy assessment of the calibration performance. Simulations and real data experiments are designed and conducted to validate the effectivity of the method and analyze its performance under different network geometries. The RMSE of length measurement is less than 0.25 mm and the relative precision is higher than 1/25,000 for a two camera system calibrated by the proposed method in a volume of 12 m × 8 m × 4 m. Compared with the state-of-the-art point array self-calibrating bundle adjustment method, the proposed method is easier to operate and can significantly reduce systematic errors caused by wrong scaling.
关键词： scale bar,relative orientation,self-calibration,stereo photogrammetry,3D vision
更新于2025-09-04 15:30:14