| 1. |
- Andersen, Olav, et al.
(författare)
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Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:2, s. 248-254
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Tidskriftsartikel (refereegranskat)abstract
- A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.
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| 2. |
- Andersson, Tomas, et al.
(författare)
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IEEE standard 1057, Cramer-Rao bound and the parsimony principle
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9456 .- 1557-9662. ; 55:1, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with some fundamental properties of the sine-wave-fit algorithm included in IEEE Standards 1057 and 1241. Asymptotic Cramer-Rao bounds (CRBs) for three and four model parameters are derived under the Gaussian assumption. Further, the sine-wave-fitting properties of the algorithm are analyzed by the parsimony principle. A decision criterion whether to use the three- or four-parameter model is derived. It is shown that a three-parameter sine-wave fit produces a better fit than the four-parameter fit if the frequency is known to be within an interval related to the number of samples and the signal-to-noise ratio. By a numerical analysis, the theoretical results are shown to be also valid for the uniform noise model of quantization.
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| 3. |
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| 4. |
- Björsell, Niclas, et al.
(författare)
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Histogram Tests for Wideband Applications
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 57:1, s. 70-75
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Tidskriftsartikel (refereegranskat)abstract
- Characterization and testing of analog-to-digital converters (ADCs) are important for many reasons. A histogram test is a common method to characterize the linearity features of an ADC. Two commonly used stimulus signals are sine waves and Gaussian noise. This paper presents a metrological comparison between Gaussian and sine-wave histogram tests for wide-band applications, that is, we evaluate the performance of the characterization of the ADC and the usability of postcorrection. A postcorrection procedure involves the characterization of the ADC nonlinearity and then the use of this information by processing the ADC output samples to remove the distortion. The results show that the Gaussian histogram test gives reasonable accuracy in measuring nonlinearities. However, it does not result in a suitable model for postcorrection in wideband applications. A single-tone sine-wave histogram will be a better basis for postcorrection. The best result can be obtained if the lookup table is trained with several single-tone sine waves in the frequency band.
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| 5. |
- Björsell, Niklas, et al.
(författare)
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Measuring Volterra Kernels of Analog To Digital Converters Using a Stepped Three-Tone Scan
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 57:4, s. 666-671
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Tidskriftsartikel (refereegranskat)abstract
- The Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converters (ADCs). This paper describes how frequency-domain Volterra kernels of an ADC are determined from measurements. The elements of the Volterra theory are given, and practical issues are considered, such as methods for signal conditioning and finding the appropriate test signals scenario and suitable sampling frequency. The results show that, for the used pipeline ADC, the frequency dependence is significantly stronger for second-order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second-order Volterra kernel. It is suggested that the Volterra kernels have the symmetry properties of a specific box model, namely, the parallel Hammerstein system.
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| 6. |
- Båvall, Lennart, 1945-
(författare)
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Determination of thickness of silver coatings on brass by measuring the impedance of a thin elliptic coil
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:3, s. 790-799
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Tidskriftsartikel (refereegranskat)abstract
- To measure the impedance of a thin elliptically shaped coil, in presence of a flat plate with a coat of metal, can be an instrument for determination of the cladding thickness. An electromagnetic field from the coil is then forced to the object, producing eddy currents inside the object. These are influenced by the characteristics of the object and the coil and give rise to an impedance change, which can be detected and correlated to the thickness of the coating. An electromagnetic model accounting for the impedance of the elliptic coil with different values on the numerical eccentricity and the coating thickness is described. The model is based on a dyadic Green function formulation of the problem from which the electric field and hence the impedance is evaluated by utilizing the method of scattering super position. Numerical calculations based on the model and experimental measurements have been taken. An example shows how the model can be used to model a brass surface with a coat of silver to find expected impedance as function of the coating thickness
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| 7. |
- De Angelis, Alessio, et al.
(författare)
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A Low-Cost Ultra-Wideband Indoor Ranging System
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:12, s. 3935-3942
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a low-cost indoor ranging technique based on time-of-arrival (TOA) estimation, using short-pulse ultra-wideband (UWB) signals. The realized system includes two identical UWB transceiver devices, in which the receiver section is based on a tunnel diode detector and the pulse generation is performed by a common bipolar transistor driven in avalanche mode. An indirect measurement of the distance between the devices is obtained by measuring the frequency of the generated pulse train. A theoretical model of the system is described, and a statistical analysis is presented, including the closed-form evaluation of the Cramer-Rao lower bound (CRLB) on the distance estimation and showing the asymptotic statistical efficiency of the proposed estimators. Furthermore, the principle of operation of the realized system prototypes is described, along with some implementation issues. Finally, experimental results are shown and discussed.
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| 8. |
- De Angelis, Alessio, et al.
(författare)
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A Vector Approach for Image Quality Assessment and Some Metrological Considerations
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:1, s. 14-25
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this paper is to present a metrology-based view of the image quality assessment (IQA) field. Three main topics are developed. First, the state of the art in the field of IQA is presented, providing a classification of some of the most important objective and subjective IQA methods. Then, some aspects of the field are analyzed from a metrological point of view, also through a comparison with the software quality measurement area. In particular, a statistical approach to the evaluation of the uncertainty for IQA objective methods is presented, and the topic of measurement modeling for subjective IQA methods is analyzed. Finally, a vector approach for full-reference IQA is discussed, with applications to images corrupted by impulse and Gaussian noise. For these applications, the vector root mean squared error (VRMSE) and fuzzy VRMSE are introduced. These vector parameters provide a possible way to overcome the main limitations of the mean-squared-error-based IQA methods.
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| 9. |
- De Angelis, Alessio, et al.
(författare)
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Characterization and Modeling of an Experimental UWB Pulse-Based Distance Measurement System
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:5, s. 1479-1486
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a distance-measuring system based on the accurate round-trip time-of-flight measurement of single ultrawideband pulses propagating between two transceiver devices. The architectures of two realized devices, which are referred to as the master and the slave, are described. The master device implements the time-interval measuring function by means of a time-to-digital converter (TDC) integrated circuit, whereas the slave acts as a pulse repeater. Both devices are designed for low-cost realization and low-power operations. Furthermore, two pulse-detection modules are described based on signal-threshold and energy detection, respectively. This paper also presents and discusses some experimental results that are obtained from the system prototype. Finally, some numerical simulation results, which provide an explanation for the nonidealities in the observed distance-measuring behavior of the system, are shown.
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| 10. |
- De Vito, Luca, et al.
(författare)
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Bayesian calibration of a lookup table for ADC error correction
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:3, s. 873-878
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new method for the correction of nonlinearity errors in analog-to-digital converters (ADCs). The method has been designed to allow a self-calibration in systems where an internal signal can be generated, such as base stations for mobile communications. The method has been implemented and tested in simulation on the behavioral model of commercial ADCs and on a hardware setup composed by a data acquisition board and a distorting circuit.
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| 11. |
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| 12. |
- Hallström, J., et al.
(författare)
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Worldwide comparison of lightning impulse voltage measuring systems at the 400-kV level
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:2, s. 388-391
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Tidskriftsartikel (refereegranskat)abstract
- An international comparison of lightning and switching impulse voltage measuring systems was arranged and coordinated by the Helsinki University of Technology (MIKES-TKK), Espoo, Finland, between 1999 and 2002. The number of participants was 26, including the coordinator. This paper summarizes the results obtained by those eight National Metrology Institutes that participated in the comparison. A 400-kV transfer reference measuring system for measuring lightning impulse voltages was prepared by the coordinator. In addition, a 1-kV impulse voltage calibrator system, including calibrators for both standard lightning and switching impulses, was circulated. © 2007 IEEE.
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| 13. |
- Händel, Peter, 1962-, et al.
(författare)
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A calibration scheme for imperfect quantizers
- 2000
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 49:5, s. 1063-1068
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Tidskriftsartikel (refereegranskat)
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| 14. |
- Händel, Peter, 1962-
(författare)
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Discounted Least-Squares Gearshift Detection Using Accelerometer Data
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9456 .- 1557-9662. ; 58:12, s. 3953-3958
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Tidskriftsartikel (refereegranskat)abstract
- A gearshift detector based on accelerometer readings is derived, and its performance is investigated with the aid of experimental data. The employed methodology contains a low-order parametric model of the acceleration performed by the vehicle in combination with the minimization of a fading-memory least-squares criterion for parameter estimation and tracking. It is shown that the resulting filtering equations converge so that filtered accelerometer outputs (i.e., instantaneous acceleration and its rate of change) are obtained by linear time-invariant filtering of the raw accelerometer data, where the tradeoff between noise suppression and tracking ability is entirely determined by a single user-chosen variable. Two detection variables are formed, and they are combined to produce the detector output. Evaluation on experimental data illustrates the potential of the proposed method.
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| 15. |
- Händel, Peter, 1962-
(författare)
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Parameter estimation employing a dual-channel sine-wave model under a Graussian assumption
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 57:8, s. 1661-1669
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Tidskriftsartikel (refereegranskat)abstract
- The Cramer-Rao bound (CRB) is a lower bound on the error variance of any estimator. For a Gaussian scenario, the CRB is derived for a seven-parameter, dual-channel sine-wave model, which is a model relevant to applications such as impedance measurements and the estimation of particle size and velocity by laser anemometry. Four different parameterizations; were considered: the common quadrature/in-phase and amplitude-phase models and two relative amplitude-phase models. The CRB indicated the achievable error variance of an unbiased estimator as a function of the signal-to-noise ratio (SNR), the number of samples, and noise power. A nonlinear least squares fit of the signal model to the collected data was employed. The problem at hand is separable and can be solved by a I-D search followed by a linear least squares fit of the remaining parameters. The performance of the method was investigated with the aid of a simulation study, and the outcome was compared with that of the corresponding CRB and with a recently proposed seven-parameter fit. For high SNRs, the performance of the proposed method is close to optimal with an error variance close to the predictions made by the CRB.
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| 16. |
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| 17. |
- Karlsson, Beatrice, et al.
(författare)
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A fusion toolbox for sensor data fusion in industrial recycling
- 2002
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9456 .- 1557-9662. ; 51:1, s. 144-149
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Tidskriftsartikel (refereegranskat)abstract
- Information from different sensors can be fused in various ways. It is often difficult to choose the most suitable method for solving a fusion problem. In a measurement situation, the measured signal is often corrupted by disturbances (noise, etc.). It is, therefore, meaningless to compare crisp values without the corresponding uncertainty intervals. This paper describes a toolbox including nine different fusing methods. All methods are applied on training data, and the most suitable method is then used for solving the real fusion problem. In the example, fusion is performed on data for classification in an industrial recycling operation. The data is from different vision systems and an eddy current system. The fusion methods included in the toolbox are fuzzy logic with triangular and Gaussian shaped membership functions, fuzzy measures with triangular and Gaussian shapes, Bayes' statistics, artificial neural networks, multivariate analysis (PCA), a knowledge-based system, and a neuro-fuzzy system.
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| 18. |
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| 19. |
- Lauwers, Lieve, et al.
(författare)
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A Nonlinear Block Structure Identification Procedure using Frequency Response Function Measurements
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE Instrumentation and Measurement Society. - 0018-9456 .- 1557-9662. ; 57:10, s. 2257-2264
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Tidskriftsartikel (refereegranskat)abstract
- Based on simple Frequency Response Function (FRF) measurements, we give the user some guidance in the selection of an appropriate nonlinear block structure for the system to be modeled. The method consists in measuring the FRF using a Gaussian-like input signal and varying in a first experiment the root-mean-square (rms) value of this signal while maintaining the coloring of the power spectrum. Next, in a second experiment, the coloring of the power spectrum is varied while keeping the rms value constant. Based on the resulting behavior of the FRF, an appropriate nonlinear block structure can be selected to approximate the real system. The identification of the selected block-oriented model itself is not addressed in this paper. A theoretical analysis and two practical applications of this structure identification method are presented for some nonlinear block structures.
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| 20. |
- Lundin, Henrik, et al.
(författare)
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A criterion for optimizing bit-reduced post-correction of AD converters
- 2004
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 53:4, s. 1159-1166
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic digital post-correction of analog-to-digital converters (ADCs) is considered. A generalized dynamic correction method is proposed and a framework for analyzing the related bit allocation problem is derived. Finally, this framework is employed in an optimization problem. The solution to the problem indicates which ADC output bits to use in order to maximize the signal-to-noise and distortion ratio in a post-correction system with a constraint on memory size. The proposed methods are accompanied by exemplary results obtained using experimental ADC data.
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| 21. |
- Lundin, Henrik, et al.
(författare)
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On the Estimation of Quantizer Reconstruction Levels
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 55:6, s. 2176-2182
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of estimating the optimal reconstruction levels of a fixed quantizer, such as the amplitude quantization part of an analog-to-digital converter. A probabilistic transfer function model is applied for the quantizer. Two different assumptions are made for the transfer function, and an estimator based on order statistics is applied. The estimator turns out to give better results in terms of mean square error than the commonly applied sample mean.
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| 22. |
- Lundin, Henrik, et al.
(författare)
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On the estimation of quantizer reconstruction levels
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9456 .- 1557-9662. ; 55:6, s. 2176-2182
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of estimating the optimal reconstruction levels of a fixed quantizer, such as the amplitude quantization part of an analog-to-digital converter. A probabilistic transfer function model is applied for the quantizer. Two different assumptions are made for the transfer function, and an estimator based on order statistics is applied. The estimator turns out to give better results in terms of mean square error than the commonly applied sample mean. The Cramer-Rao lower bound for the estimation problem is also considered, and simulation results indicate that the derived estimator is asymptotically efficient.
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| 23. |
- Magesacher, Thomas, et al.
(författare)
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Verification of multipair copper-cable model by measurements
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - Piscataway, N.J. : IEEE Press. - 0018-9456 .- 1557-9662. ; 56:5, s. 1883-1886
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Tidskriftsartikel (refereegranskat)abstract
- Analysis, assessment, and design of advanced wire-line transmission schemes over multipair copper cables require accurate knowledge of the channel properties. This paper investigates modeling of multiconductor cables based on interpair impedance measurements. A unified approach to the application of the "Cioffi" model is introduced. The direct measurement approach of the underlying interpair impedances yields a good, match with the alternative approach suggested in the recent study of Cioffi et al. Crosstalk coupling functions derived from the model exhibit a good match with the corresponding direct measurements in the case in which the modeled length is close to the length of the interpair impedance measurements. However, the prediction power of this model,with respect to termination impedance is limited.
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| 24. |
- Nordin, Daniel, et al.
(författare)
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Single-stage photodiode op-amp solution suited for a self-mixing FMCW system
- 2003
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 52:6, s. 1820-1824
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Tidskriftsartikel (refereegranskat)abstract
- The current delivered by the photodiode in a self-mixing frequency modulated continuous wave or optical frequency domain reflectometry system consists of a dc-current resulting from the local oscillator, the reflected signal, dark current in the photodiode, and current generated from background light. The current also contains the useful harmonic signal with a beat frequency corresponding to the range and radial velocity of a target. To avoid saturation and clipping due to the dc current generated in the photodiode, it is desirable to minimize the gain at dc while maintaining a high gain in the beat frequency region. We have investigated some different solutions and present a modified current-to-voltage converter using bootstrapping and added voltage gain, which addresses this problem using only one OP-amp and no dc shorting inductors.
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| 25. |
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| 26. |
- Rönnow, Daniel, et al.
(författare)
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Three-Tone Characterization of Nonlinear Memory Effects in Radio Frequency Power Amplifier
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:6, s. 2646-2657
-
Tidskriftsartikel (refereegranskat)abstract
- A stepped three-tone measurement technique based on digitally modulated baseband signals is used in characterizing radio-frequency power amplifiers (PAs). The bandwidths of the stepped measurement were 8.8 MHz for the input signal and 26.4 MHz for the output signal. A PA designed for third-generation mobile telecommunication system was analyzed. The amplitude and phase of the third-order Volterra kernel were determined from the identified intermodulation products. The properties of the Volterra kernel along certain paths in the 3-D frequency space were analyzed and compared to some box models for non-linear systems. The main symmetry of the third-order Volterra kernel of this PA was found to be of the type given by the cascaded quadratic nonlinearities with a linear filter in between (a Hammerstein-Wiener system), and frequency dependence, i.e., memory effects, was found to be due to the effects at the baseband.
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| 27. |
- Spännar, Jan, et al.
(författare)
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A method for measuring strip temperature in the steel industry
- 2002
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 51:6, s. 1240-1245
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Tidskriftsartikel (refereegranskat)abstract
- In the steel industry, there are many processes that include measuring and control of temperatures. With higher demand on quality, increased production, and effective energy consumption, the use of noncontact temperature measuring techniques has increased. After the cooling section in a continuous annealing-pickling line, the strip temperature is estimated by using the grey box technique. Temperatures are measured in the cavity between the strip and the roller using radiation thermometers. A model is made for estimating strip temperature using the measured temperatures and knowledge of the physics of the process.
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| 28. |
- Stenarson, Jörgen, et al.
(författare)
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Uncertainty Propagation Through Network Parameter Conversions
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:4, s. 6-
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a simplified procedure to obtain the uncertainties when converting a set of network parameters to another form. The method is based on a general matrix transformation technique. The technique relies on a transformation matrix that describes the relation between two network parameter definitions and two matrix equations. This paper extends the technique with two new matrix equations to also transform the uncertainties in the network parameters by relying on the same transformation matrix. The proposed method is exemplified by the conversion of S-parameter measurements with uncertainty (of a 30-dB attenuator) to G21 with uncertainty. The proposed method for uncertainty conversion is also compared with an analytic expression for S-parameter to G21 conversion.
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| 29. |
- Wernholt, Erik, et al.
(författare)
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Estimation of nonlinear effects in frequency-domain identification of industrial robots
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 57:4, s. 856-863
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Tidskriftsartikel (refereegranskat)abstract
- A method for the detection and estimation of nonlinear distortions when identifying multivariable frequency response functions (FRF) is considered. The method is successfully applied to experimental data, which were collected in closed loop, from an industrial robot. The results show that nonlinear distortions are indeed present and cause larger variability in the FRF than the measurement-noise contributions.
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| 30. |
- Wirandi, Jenny, et al.
(författare)
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An Adaptive Quality Assessment System-Aspect of Human Factor and Measurement Uncertainty
- 2009
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Ingår i: IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT. - : IEEE. ; 58:1, s. 68-75
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Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss a model of quality that makes use of the fuzzily defined variable approach to better understand the concept and, thus, enables the further development of this variable. We propose a general method that may estimate a quality index (QI) that handles both qualitative and quantitative issues. The system further uses a neural network since the system learns how to integrate human factors into a quantitative QI. In our case study, we have examined the measurement of image quality and proposed a theoretical model of pulp quality.
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| 31. |
- Wirandi, Jenny, et al.
(författare)
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Problem of applying modern uncertainty concepts to the measurement of instrument-specific parameters
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 55:3, s. 700-705
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a number of problems that occur when applying the Guide to the Expression of Uncertainty in Measurement (GUM) to modern instruments. These instruments are often automatic, which makes it complicated to evaluate the uncertainty components in each measurement step because it is difficult to control and analyze them. Many of these instruments try to quantify instrument-specific parameters, which are difficult to compare with others that have the same dimension but are measured using other techniques. Often, these parameters lack traceable calibration, which may result in a large uncertainty component. This paper also considers the human aspect of the measurement process. © 2006 IEEE.
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| 32. |
- Wisell, David, et al.
(författare)
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A technique to extend the bandwidth of an RF power amplifier test bed
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:4, s. 1488-1494
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a method for increasing the bandwidth of a test bed for dynamic characterization of power amplifiers (PAs) is described. The technique is readily implemented using commercially available instruments, which makes it suitable for, e.g., production testing. The bandwidth extension technique is combined with coherent averaging of the measurements in order to simultaneously increase the bandwidth and dynamic range of the test bed. The errors in the obtained wideband signal are also estimated. The method is evaluated experimentally on a base station PA for the third-generation wideband code division multiple access system and on a Doherty amplifier. A tenfold increase in bandwidth to a total of 144 MHz and a more than 10-dB increase in dynamic range to 78 dB were obtained in practice. In addition, the obtained wideband signal is used for behavioral amplifier modeling.
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| 33. |
- Wisell, David, et al.
(författare)
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Characterization of memory effects in power amplifiers using digital two-tone measurements
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 56:6, s. 2757-2766
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a novel method to measure the amplitude and phase of two-tone third-order intermodulation products generated in a high-power amplifier is presented. The method is based on the sampled input and output signals of the amplifier. The presented measurement setup and the associated algorithms for the calculation of the amplitudes and phases are considerably faster and simpler than the current methods. By making use of the sampled input and output signals of the amplifier and the signal processing techniques, the need for a nonlinear reference, a tunable attenuator, and a phase shifter in the existing measurement setups is eliminated, which makes it simple and easy to use. Hence, this is a substantial simplification of the measurement setup compared to what has been reported earlier. The proposed measurement setup is also suitable for fast automated measurements, which is of interest for many applications that are both laboratory and production oriented. In addition, a method to increase the bandwidth of the measured signal is used to overcome the bandwidth limitation set by the Nyquist criteria for sampled systems. Measurements are done on two base-station high-power amplifiers and are found to be in agreement with theory and reference measurements.
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| 34. |
- Dubickas, Valentinas, et al.
(författare)
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High-Frequency Model of the Rogowski Coil With a Small Number of Turns
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurements. - 0018-9456. ; 56:6, s. 2284-2288
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the Rogowski coil is modeled as adistributed-element transmission line. The elements in the distributedtransmission line are modeled using physically basedequations. It allows self and transfer impedances of the Rogowskicoil to be modeled using the physical dimensions and the materialproperties of the coil. The models of the impedances were verifiedby measurements in the frequency domain on three Rogowskicoils. The coils mounted on the power cable were modeled andsimulated in the time domain and afterward compared with themeasurements.
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| 35. |
- Lundbäck, Jonas, et al.
(författare)
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A Digital Directional Coupler with Applications to Partial Discharge Measurements
- 2008
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Ingår i: IEEE Transactions on Instrumentation and Measurements. - 0018-9456. ; 57:11, s. 2561-2567
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a digital directional coupler (DDC) that separates forward- and backward-traveling waves on a transmission line. Based on two independent wideband measurements of voltage and current and on frequency-domain digital wave splitting using a fast Fourier transform (FFT), the DDC is a versatile device for direction separation. A practical procedure is described for the calibration of the digital processor with respect to the particular transmission line and the voltage and current sensors that are being used. As an experiment, a DDC was designed and implemented using low-cost wideband sensors and was installed with medium-voltage equipment in a power distribution station. Partial discharge (PD) measurements were conducted on cross-linked polyethylene (XLPE)-insulated power cables to illustrate the directional separation capabilities of the DDC.
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| 36. |
- Spännar, Jan, et al.
(författare)
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A method for measuring strip temperature in the steel industry
- 2005
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456. ; 51:6
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Tidskriftsartikel (refereegranskat)abstract
- In the steel industry, there are many processes that include measuring and control of temperatures. With higher demand on quality, increased production, and effective energy consumption, the use of noncontact temperature measuring techniques has increased. After the cooling section in a continuous annealing-pickling line, the strip temperature is estimated by using the grey box technique. Temperatures are measured in the cavity between the strip and the roller using radiation thermometers. A model is made for estimating strip temperature using the measured temperatures and knowledge of the physics of the process.
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