- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A Phase-Calibration Method for Vector-Sum Phase Shifters Using a Self-Generated LUT
摘要： This paper presents a new self-calibration method for vector-sum phase shifters (PS) to compensate for process variations and achieve reconfigurable operating frequency. The calibration system generates a look-up table for the control voltages of the variable-gain amplifiers of the PS to minimize the rms phase error at a frequency of interest. The calibration system consists of a coupled-line coupler, an amplifier, a power detector (PD), an analog-to-digital converter, and a data processing unit. In this calibration method, first, the amplitudes of IQ vectors are swept and their powers are measured. Then, phase errors are calculated from these power measurements using the cosine formula. Finally, the vector pairs providing the least phase error are chosen for each desired phase shift. The practicality of the proposed system is demonstrated by realizing a self-calibrated X-band 7-b PS fabricated in IHP 0.25-μm SiGe BiCMOS technology, including the on-chip coupler, amplifier, and PD. The calibration system improves the rms phase error by at least 1°, does not degrade the rms gain error, and increases the insertion loss by 1.6 dB. The self-calibrated PS achieves a 2° rms phase error across X-band frequencies. The overall chip size is 2.6 mm2. The power consumption of the PS and the overall system are 110 and 233 mW, respectively. This built-in calibration system mitigates process variation effects, and the performance of the PS can be optimized for any center frequency across X-band.
关键词： BiCMOS,vector-sum phase shifter,look-up table,Self-calibration,process compensation,phase shifter,SiGe
更新于2025-09-23 15:23:52
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Self-calibration of projective camera based on trajectory basis
摘要： To calibrate the projective camera, this paper presents a linear method for self-calibration of a projective camera based on the representing of deforming object by the trajectory basis. The trajectory basis can be modeled compactly in the domain of the Discrete Cosine Transform (DCT) basis vectors which can be predefined independent of the observed images, and the number of unknowns can be significantly reduced. At the same time, the camera self-calibration becomes a linear optimal problem, which can improve the robustness of the algorithm. The experiments with both simulate and real data show that the presented method can effectively calibrate the camera.
关键词： Non-rigid,Trajectory basis.,Self-calibration
更新于2025-09-23 15:23:52
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Self-Calibration of Traffic Surveillance Cameras Based on Moving Vehicle Appearance and 3-D Vehicle Modeling
摘要： This paper proposes an effective and practical method for self-calibration of traffic surveillance cameras. Based on analyzing multiple moving vehicles across multiple frames, the Canny edge detector and Hough transform are first adopted to obtain orthogonal horizontal vanishing points pairs, from which corresponding vertical vanishing points are derived. Next, mean shift clustering and Laplace linear regression are employed to deal with noise and outliers during estimation of vanishing points. To overcome the unreliable estimation issues of orthogonal vanishing points pairs, we further utilize the projective line segments obtained from 3-D vehicle model to create more reliable pairs and iteratively improve the calibration results. Finally, the estimation of distribution algorithm (EDA) is also applied to relax the assumptions made on camera parameters and the moving trajectories of vehicles during the iterations. Experimental results on different datasets prove the feasibility of our proposed scheme.
关键词： horizon line,EDA optimization,traffic camera self-calibration,3-D vehicle modeling,vanishing points
更新于2025-09-23 15:23:52
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3D surface reconstruction of retinal vascular structures
摘要： We propose in this paper, a three-dimensional surface reconstruction of a retinal vascular network from a pair of 2D retinal images. Our approach attempts to address the above challenges by incorporating an epipolar geometry estimation and adaptive surface modelling in a 3D reconstruction, using three steps: segmentation, 3D skeleton reconstruction and 3D surface modelling of vascular structures. The intrinsic calibration matrices are found via the solution of simplified Kruppa equations. A simple essential matrix based on a self-calibration method has been used for the ‘fundus camera-eye’ system. The used method has eventually produced vessel surfaces that could be fit for various applications, such as applications for computational fluid dynamics simulations and applications for real-time virtual interventional.
关键词： Kruppa equations,curvature-dependent subdivision,surface reconstruction,epipolar geometry,segmentation,retinal vascular network,self-calibration
更新于2025-09-23 15:22:29
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Femtosecond-laser photoemission spectroscopy for ultrafast photovoltage dynamics: limitations and possibilities
摘要： In this paper, we study the time-of-arrival (TOA) based self-calibration problem of dual-microphone array for known and unknown rack distance, and also for different combinations of dimension for the af?ne spaces spanned by the receivers and by the senders. Particularly, we analyze the minimum cases and present minimum solvers for the case of microphones and speakers in 3-D/3-D, in 2-D/3-D, and in 3-D/2-D, with given or unknown rack length. We identify for each of these minimal problems the number of solutions in general and develop ef?cient and numerically stable, non-iterative solvers. Solving these problems are of both theoretical and practical interest. This includes understanding what the minimal problems are and how and when they can be solved. The solvers can be used to initialize local optimization algorithms for ?nding the maximum likelihood estimate of the parameters. The solvers can also be used for robust estimation of the parameters in the presence of outliers, using, e.g., RANSAC algorithms. We demonstrate that the proposed solvers are numerically stable in synthetic experiments. We also demonstrate how the solvers can be used with the RANSAC paradigm. We also apply our method for several real data experiments, using ultra-wide-band measurements and using acoustic data.
关键词： dual-microphone array,Time-of-arrival (TOA),minimal solver,self-calibration
更新于2025-09-23 15:21:01
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A self-calibration method for error of photoelectric encoder based on gyro in rotational inertial navigation system
摘要： As a precision goniometer, photoelectric encoder plays an important role in rotational inertial navigation system (RINS). The encoder is used to measure the rotate angle of rotating mechanism for attitude calculation and feedback of motor control. However, the experiment shows that there are position-related errors in the encoder output, so calibration is necessary in high precision applications. This paper presents a calibration method designed by the characteristics of encoder errors and the structure of a tri-axis RINS. In RINS, the gyro sensitive axis can be coincided with the motor axis by gimbals rotation, and then the gyro and the photoelectric encoder measure the same angle, so the error can be calculated as the difference between the encoder output and the integral of gyro output. The error will be analyzed through Fourier method, then the error will be ?tted by least squares method and a harmonic model will be established. The veri?cation experiments demonstrate that the angle measurement error is reduced from ± 4000 to ± 200, and the attitude output error drops 7500. The calibration method is proved to be experimentally effective.
关键词： error compensation,gyro,rotational inertial navigation system,self-calibration,photoelectric encoder
更新于2025-09-23 15:21:01
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A Full-Parameter Self-Calibration Method Based on Inertial Frame Filtering for Triaxis RINS under Swaying Base
摘要： The navigation performance of the rotational inertial navigation system (RINS) could be greatly improved by self-calibration traditional instrument-level calibration depends on high-precision turntable. System-level calibration takes zero velocity as reference to estimate error parameters. However, zero velocity is invalid in the situation of swaying base and the calibration accuracy will be decreased with the traditional method. Aiming at the swaying base environment, the filtering method for tri-axis RINS in inertial frame is proposed in this paper. Taking the velocity errors in the inertial frame as the reference, full-parameter calibration on swaying base can be achieved. Simulation verifies the feasibility of the proposed method. Experimental results demonstrate the stability of the proposed method is better than the traditional calibration method and it satisfies the application requirements. Thus, the proposed method has great application values under swaying base.
关键词： Swaying base,Filtering,Self-calibration,Inertial frame,RINS
更新于2025-09-23 15:19:57
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Quantitative analysis of saindha salt using laser induced breakdown spectroscopy and cross-validation with ICP-MS
摘要： Saindha salt is considered to be more advantageous than the other edible salts for the patients suffering from diabetes, blood pressure and kidney diseases. To explore the constituent elements of this salt, laser induced breakdown spectroscopy (LIBS) has been exploited for its qualitative and quantitative analysis. The third harmonic (355 nm) of a Q-switched Nd:YAG laser has been used to produce the saindha salt plasma and the time integrated optical emission spectra were registered using a set of six miniature spectrometers covering the spectral range of 230–805 nm. The spectroscopic analysis of the emission spectra predominately revealed numerous neutral or singly ionized emission lines of Ca, Mg, Na, K, Fe, Sr, Si, Li and Al. The laser produced plasma was characterized by calculating the electron temperature from the Boltzmann plots and the electron number density from the Stark broadened line profile as a function of laser irradiance and distance from the target sample. The relative concentration of the constituent elements was extracted by the integrated line intensities of the strongest spectral line of each element using the self-calibration-LIBS (SC-LIBS) and one-line calibration free-LIBS (OLCF-LIBS) methods. For cross-validation, the LIBS results have been compared with that obtained from the inductively coupled plasma-mass spectroscopy (ICP-MS) showing good agreement.
关键词： inductively coupled plasma-mass spectroscopy,saindha salt,elemental analysis,one-line calibration-free LIBS,self-calibration-LIBS,plasma parameters
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th Global Conference on Consumer Electronics (GCCE) - Osaka, Japan (2019.10.15-2019.10.18)] 2019 IEEE 8th Global Conference on Consumer Electronics (GCCE) - Swallowing Measurement for a Healthy Subject Using a Hetero-Core Optical Fiber Sensor
摘要： In this paper, we study the time-of-arrival (TOA) based self-calibration problem of dual-microphone array for known and unknown rack distance, and also for different combinations of dimension for the af?ne spaces spanned by the receivers and by the senders. Particularly, we analyze the minimum cases and present minimum solvers for the case of microphones and speakers in 3-D/3-D, in 2-D/3-D, and in 3-D/2-D, with given or unknown rack length. We identify for each of these minimal problems the number of solutions in general and develop ef?cient and numerically stable, non-iterative solvers. Solving these problems are of both theoretical and practical interest. This includes understanding what the minimal problems are and how and when they can be solved. The solvers can be used to initialize local optimization algorithms for ?nding the maximum likelihood estimate of the parameters. The solvers can also be used for robust estimation of the parameters in the presence of outliers, using, e.g., RANSAC algorithms. We demonstrate that the proposed solvers are numerically stable in synthetic experiments. We also demonstrate how the solvers can be used with the RANSAC paradigm. We also apply our method for several real data experiments, using ultra-wide-band measurements and using acoustic data.
关键词： dual-microphone array,Time-of-arrival (TOA),minimal solver,self-calibration
更新于2025-09-19 17:13:59
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[IEEE 2019 Twelfth International Conference "Management of large-scale system development" (MLSD) - Moscow, Russia (2019.10.1-2019.10.3)] 2019 Twelfth International Conference "Management of large-scale system development" (MLSD) - Controlled Coherent Effects in Monitoring Processes of Liquid Media
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： digital trimming,mismatch correction,self-calibration,Analog-to-digital (A/D) conversion
更新于2025-09-19 17:13:59