1,721,057 research outputs found
Digital measuring techniques for high accuracy ultrasonic sensor application
No full textUltrasonic sensors level measurements are based on the determination of the time-of- flight (ToF). Owing to both the rising time and the time resolution, traditional techniques produce poor estimations of the ToF. Furthermore, the noise presence is cause of further inaccuracy. The main aim of the paper is to show how the accuracy of the ToF can be improved by adopting simple interpolation algorithms in conjunction with the Wavelet transform (WT) technique. After examining and characterizing the different error components, brief theoretical considerations on WT are reported and the effects of this choice on the accuracy are examined. It is proved that in this case the accuracy of the level measurements is very high. Finally, the performance of proposed algorithms has been verified by means of computer simulations and experimental setup
Instantaneous power measurement in time‐frequency domain
No full textThe paper deals with an originai application oj the Short-Time Fourier Transform (STFT) to instantaneous power measurements. This technique can be easily implemented in a dedicated instrument to perform accurate time-frequency analysis ofthe time-varying harmonic contents ofnetwork powers (in their active and imaginary components), which are typically non-stationary signals. Moreover, new algorithms have been examined carefully and developed to attain high levels ofaccuracy,flexibility and efficiency through STFT-PD (Power Distribution). Particularly, optimized interpolationformulas were used, derivedfrom the windowing theory to reduce the negative effects due to leakage during instantaneousfrequency changes. The effectiveness ofthe suggested technique and, particularly, the high level of accuracy achieved in time-varying amplitude andfrequency measurements ofthe analysed components of instantaneous powers and currents has been proven by means of suitable simulations
Evaluating Measurement Uncertainty in A/D Converters with and without Dither
No full textThe paper gives formulae for evaluating the uncertainty of measurements (both “direct” and “indirect”, i.e. functions of measurements) performed through an ADC-based device (like an oscilloscope, a plug-in DAQ board, etc.). The way of modeling the errors and writing the specifications is discussed. The mathematically complex but nowadays common technique of dithering is also analyzed. The results are intended as a contribution towards a standard way of writing and using ADC specifications
Pannelli fotovoltaici: Un sistema per la caratterizzazione e il monitoraggio
No full textL’articolo presenta i principali risultati scientifici in termini di valutazione di incertezza di un sistema per la caratterizzazione e il monitoraggio di pannelli fotovoltaici in condizioni operative reali o simulate. Il sistema, a partire dall’acquisizione della caratteristica I-V di un pannello in una qualsiasi condizione ambientale, permette la stima delle resistenze serie e parallelo del relativo modello. La procedura sviluppata consente di simulare in modo realistico le prestazioni di un impianto realizzato con una combinazione arbitraria di pannelli identici in una qualsivoglia condizione ambientale, in modo da stimare la produttività dell’impianto stesso prima che esso sia realizzato
Low-cost accurate characterization of FM sine wave generators
No full textA DSP-based test system for FM signal generators is presented. The proposed measurement procedure is based on the economical software implementation of an ADC linearization algorithm followed by an accurate Short-Time Fourier Transform analysis with spectral interpolation. The very good accuracy performance of the system are illustrated through computer simulation and experimental results
Standardizing the metrological assessment of waveform digitizers: problems and perspectives
No full textThe problem of the metrological qualification of data acquisition systems and of waveform recorders is a fundamental issue for both users and manufacturers of digital instruments. The need for an improved industry standard leading to unification and standardization in this field is a very pressing requirement. Users have to receive technical specifications written in standard format and manufacturers have to obtain this information following standard test procedures. The main goal of this paper is to underline the need of unifying the modeling, identification and optimization of ADC-based systems, by minimizing the number of experimental procedures to be employed. This work, more than giving solutions, is intended to state clearly a set of problems that we hope will gain the attention of researchers in this field
INL Reconstruction of A/D Converters via Parametric Spectral Estimation
No full textThe work presented in this paper builds on previous
research done by the authors in detailing a novel procedure for
obtaining a very fast measurement of the integral nonlinearity of
an analog-to-digital converter (ADC). The core of the method is
the parametric spectral estimation of the ADC output; the static
characteristic is subsequently reconstructed as a sum of Chebyshev
polynomials, in accordance with a previously developed procedure.
The method allows one to test an ADC with sinusoids of any reasonable
amplitude (even a slight overdrive is allowed), frequency
(no synchronization is needed), and phase (which is digitally compensated).
This approach is less accurate than the histogram test
but incomparably faster (about 8000 samples are sufficient regardless
of the ADC resolution)
Uncertainty analysis of degradation parameters estimated in long-term monitoring of photovoltaic plants
No full textSetup Sperimentale per la Caratterizzazione di Materiali Magnetici Dolci attraverso il Metodo Voltamperometrico
No full textEffect of A/D conversion static errors on magnetic accommodation measurements
No full textIn this paper we analyze how static errors of Analog-to-Digital converters (ADCs) can influence the measurement of magnetic phenomena such as accommodation in soft hysteretic materials. The discussion is carried out through a series of simulation of ADC response curves and applied to simulated signals and data measured on a toroidal soft ferrite core. The final purpose of this work is to analyze the impact of INL on the measurement of the accommodation phenomenon of minor loops in soft magnetic materials
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