Measuring system for time variant impedances

Kantz, J.; Waldmann, J.; Landstorfer, F.M.

doi:10.1109/imtc.2003.1207964

Cited by 3 publications

(4 citation statements)

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“…We also considered the LPM-VBS with one-sided kernel so that the online performances of various identification methods can be fairly compared. In the BEM method, polynomial basis functions were employed, and a set of expansion orders p BEM = [1,5,10,15,20] was tested to determine the one with the best EMSD value for further comparison with other TVLS methods. For RLS, a set of forgetting factors λ = [0.8, 0.85, 0.9, 0.95, 0.99] was tested, and the results with the best EMSD performance were selected for further comparison.…”

Section: Random-coefficient Linear Systemsmentioning

confidence: 99%

“…D YNAMIC systems with time-varying behaviors, such as time-varying impedances in coaxial resonators [1], time-varying channels in wireless-communication systems [2], nonstationary mechanisms of physiological systems [3], fluctuations in power distribution systems [4], etc., are frequently encountered in various engineering applications. Given a dynamic system with known input and output measurements, it is crucial to accurately identify the underlying dynamics of the system for predicting future measurements and detect-ing system variations, for example, for fault detection, etc.…”

Section: Introductionmentioning

confidence: 99%

“…However, the estimated coefficients may not always converge to the true coefficients, and such application of the TVLS to ARMA and ARMAX models still requires a more detailed analysis. Numerous methods have been proposed to identify or estimate the time-varying coefficients a(t) of the TVLS in (1). They can be broadly classified into three categories [5]: adaptive filtering/Kalman filtering (KF), basis expansion modeling (BEM), and weighted least square (LS) (WLS) methods.…”

Section: Introductionmentioning

confidence: 99%

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Local Polynomial Modeling and Variable Bandwidth Selection for Time-Varying Linear Systems

Chan¹,

Zhang²

2011

IEEE Trans. Instrum. Meas.

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This paper proposes a local polynomial modeling (LPM) approach and variable bandwidth selection (VBS) algorithm for identifying time-varying linear systems (TVLSs). The proposed method models the time-varying coefficients of a TVLS locally by polynomials, which can be estimated by least squares estimation with a kernel having a certain bandwidth. The asymptotic behavior of the proposed LPM estimator is studied, and the existence of an optimal local bandwidth which minimizes the local mean-square error is established. A new data-driven VBS algorithm is then proposed to estimate this optimal variable bandwidth adaptively and locally. An individual bandwidth is assigned for each coefficient instead of the whole coefficient vector so as to improve the accuracy in fast-varying systems encountered in fault detection and other applications. Important practical issues such as online implementation are also discussed. Simulation results show that the LPM-VBS method outperforms conventional TVLS identification methods, such as the recursive least squares algorithm and generalized random walk Kalman filter/smoother, in a wide variety of testing conditions, in particular, at moderate to high signalto-noise ratio. Using local linearization, the LPM method is further extended to identify time-varying systems with mild nonlinearities. Simulation results show that the proposed LPM-VBS method can achieve a satisfactory performance for mildly nonlinear systems based on appropriate linearization. Finally, the proposed method is applied to a practical problem of voltage-flicker-tracking problem in power systems. The usefulness of the proposed approach is demonstrated by its improved performance over other conventional methods.

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Section: Random-coefficient Linear Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Local Polynomial Modeling and Variable Bandwidth Selection for Time-Varying Linear Systems

Chan¹,

Zhang²

2011

IEEE Trans. Instrum. Meas.

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“…Works presented in [5]- [7] either do not allow measurement with such power, or are not suitable for the considered RFID frequencies. Hence, alternative impedance characterization techniques have been proposed in [4], [8]- [10], that can be used to determine PICC chips' impedance, but not for different input power, nor during a communication.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Impedance Characterization Method for RFID-Type Backscatter Communication Devices

Couraud

Deleruyelle

Kussener

et al. 2018

IEEE Trans. Instrum. Meas.

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This paper presents a Radio Frequency measurement method that allows to determine electrical characteristics like scattering parameters or impedance of contactless passive chips, using common measurement devices as oscilloscope, personal computer and directional coupler. The measurements obtained using this method are as accurate as those obtained with vector network analyzer (VNA) measurements, while providing several improvements. First, the method makes it possible to measure a chip's impedance in activation state, which requires large input power, not compatible with VNA measurements. Secondly, this method realizes a real time measurement, which consists in impedance measurement as a function of time. Therefore, this real-time measurement makes possible to detect and measure the impedance changes of an actual contactless smart card's integrated circuit during a load modulation communication at different powers. Finally, this real time impedance measurement gives important information on chips electrical characteristics that can be used to optimize NFC (Near Field Communication) devices design in order to reduce the power losses within an RFID (Radio Frequency Identification) tag.

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Disposable stepped-frequency GPR and soil measurement devices

You

Cross

Foo

et al. 2010

Proceedings of the XIII Internarional Conference on Ground Penetrating Radar

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Some geophysical and geotechnical scientists would wish to non-invasively measure the electromagnetic properties of soils using inexpensive, even disposable, technology. They may even wish to develop inexpensive and compact low-power GPR equipment for such uses as teaching and mitigation of construction risks during excavation. To this end, a heuristic comparison is made between a commercial Vector Network Analyser (VNA) and two very low cost VNAs sourced from the amateur radio community. The results are used to illustrate the potential for technology transfer from amateur communications to the GPR community, in order that a wider range of technologies be available for inexpensive implementation in GPR and soil spectroscopy studies. It will be shown that even very lowcost gain and phase detection semiconductor devices can be used to develop simple GPR and soil measurement systems capable of being used in the field to compliment GPR survey interpretation, as well as for standalone soil monitoring.

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Measuring system for time variant impedances

Cited by 3 publications

References 0 publications

Local Polynomial Modeling and Variable Bandwidth Selection for Time-Varying Linear Systems

Local Polynomial Modeling and Variable Bandwidth Selection for Time-Varying Linear Systems

Real-Time Impedance Characterization Method for RFID-Type Backscatter Communication Devices

Disposable stepped-frequency GPR and soil measurement devices

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