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Sorin Nicolae Cociorva
INDOOR AIR QUALITY MEASUREMENT

A qualitative assessment of indoors air quality is presented, by the use of an electronic nose consisting of a gas sensor array, a data acquisition system and a pattern recognition system. The gas sensors are sensitive to gases polluting the indoors air but they are sensitive to indoors temperature and humidity as well. The data acquisition system overtakes the sensors specific response and outputs a characteristic pattern to the pattern recognition system. The latter, a logic neural network based system, classifies the results of the measurements on qualitative grounds and takes decisions in terms of meliorating comfort inside buildings, houses and work conditions.

H. Ndilimabaka, P. Espel, A. Poletaeff
VOLTAGE MEASUREMENTS FOR DISTORTED WAVEFORMS

This paper describes a standard system at LNE to measure RMS value of distorted voltage waveforms by means of a sampling voltmeter. Thermal converters are used to trace this quantity to the SI units. Deviations within 15 μV/V are obtained whatever the total harmonic distortion of the waveforms.

Oleh Velychko, Tetyana Gordiyenko
METHODOLOGIES OF EVALUATION OF THE GREENHOUSE GASES EMISSION FROM DIESEL TRANSPORT

Research some basis for national annual greenhouse gases (GHG) emissions evaluation for transport is national statistic data and expert evaluations. Quality and confidence of GHG inventory for transport through evaluation methodologies, preparation procedures and processing of data is confirm. Request at national GHG inventories which contain evaluation and analyses national data and expert evaluations for transport with main elements of ІРСС and EEA methodologies are determined. The use approaches ІРСС and EEA methodologies for evaluation for GHG inventory for transport are proposed. This paper covers in the development of some national evaluation methodologies for the direct GHG and precursor gases from different types of diesel transport (railways, inland waterways vessels, boats and watercrafts, etc). The GHG emission evaluation algorithms for transport according to ІРСС 2006 and for developed national guides are proposed.

E.Balestrieri, L.De Vito, S.Rapuano, D. Slepicka
ABOUT UNCERTAINTY ESTIMATION FOR ADC SPECTRAL FIGURES OF MERIT

The paper deals with the uncertainty evaluation for the most used figures of merit of analog to digital converters in technical standards. Total Harmonic Distortion (THD), Spurious-Free Dynamic Range (SFDR), Signal to-Noise And Distortion ratio (SINAD) and Signal to Noise Ratio (SNR), as defined in IEEE Std.1057, have been considered in order to derive practical uncertainty propagation formulas. The proposed formulas have been validated on simulated and actual signals generated by three different waveform generators and acquired by three waveform digitizers.

F.M. Lombardi, A. Moschitta, P. Carbone
A SINE GENERATION AND COHERENT SAMPLING SYSTEM WITH HIGH TIME ACCURACY

In this paper, a system is presented, which accurately synthesizes and coherently samples sinusoidal signals. The system, based on an atomic clock which disciplines both a signal generator and a data acquisition board, has been used to analyze the code excitation statistics of a coherently sampled sinewave, as a function of the selected sinewave parameters, including overdrive and initial phase. Experimental verifications have been carried out, aimed at investigating the problem of designing efficient stimuli for ADC testing purposes.

Marián Chovanec, Linus Michaeli, Martin Sekerák, Ján Šaliga
DIGITAL FILTERS FOR BAND-PASS SIGMA-DELTA CONVERTER FOR COMPLEX SENSOR SYSTEMS

Sigma delta modulation is useful for high performance analog-to-digital conversion of narrow band signals. Band-pass sigma delta modulation (BP ΣΔ ADC) is suitable for communication systems such as AM/FM receivers and mobile phones. Application of BP ΣΔ ADC in sensor systems is presented in the paper. BP ΣΔ ADC performs I/Q conversion of the complex impedance from two dimensional sensor into two digital values representing real and imaginary part of sensor output. The BP ΣΔ ADC is useful for outputs processing from the modulating sensors too. Implemented digital filters have important impact on the metrological properties of whole BP ΣΔ ADC. The various types of FIR and IIR filters are studied in the paper and their phase sensitivity and transmission of modulated signal are studied.

László Balogh, István Kollár, Linus Michaeli, Ján Šaliga, Jozef Lipták
EXTRACTING FULL INFORMATION FROM MEASURED ADC DATA

ADC testing is often done using sine wave excitation (see e.g. IEEE standard 1241). The measured data are fitted in least squares sense by a sine wave, and the residuals can be analyzed further. In recent papers, it has been recognized that even more (and more precise) information can be extracted by the solution of the maximum likelihood equations. This can be considered as an improvement to the three-parameter and four-parameter fits. Further investigations lead to the statement that the same principle can be extended to any measurement which uses an excitation signal which can be described with a few parameters. A candidate for this is using an exponential signal, with 3 parameters: start value, end (steady-state) value, and time constant. The maximum likelihood (ML) equations yield a solution for these more accurate than least squares (LS) fitting.

Martin Sekerák, Linus Michaeli, Ján Šaliga, Marian Chovanec
METHODS WITH A NEW APPROACH FOR MEASURE STATIC CHARACTERIZATION OF HIGH RESOLUTION DAC CONVERTERS

This paper presents two new methods for measuring the static characteristic of high resolution Digital to Analog Converters (DACs). Both proposed methods are based on the conversion of the DAC output voltage to time by using a fast comparator and a reference calibrator. The main advantage of this approach is that time can be measured in the electronic domain much more accurately than amplitude. Both methods are based on direct time measurement by a high frequency counter and on the registration of the input DAC code. From the obtained information a Personal Computer (PC) evaluates the Integral Non Linearity (INL) and the Differential Non Linearity (DNL). Another advantage of the proposed methods is the relatively low requirements on all laboratory equipment involved.

Konrad Jędrzejewski
DRIFT-LIKE ERRORS COMPENSATION IN INTELLIGENT CYCLIC A/D CONVERTERS

The paper presents the results of investigations on elimination of drift-like errors in intelligent cyclic A/D converters, in particular errors caused by drifts (droops) of voltage at the output of sample-and-hold blocks. The proposed solution is based on application of the extended multi-dimensional algorithm, which estimates simultaneously values of the input sample and the drift rate using the drift rate estimates for correction of the input sample codes. Implementation of the extended algorithm in the intelligent cyclic A/D converters requires only insignificant changes in the digital part of the converter and does not increase their production costs. The motivations to these investigations were results of practical realizations of the intelligent cyclic A/D converter in CMOS technology and difficulties in design of a precise sample-and-hold circuit. The results of selected simulation experiments related to analysis of influence of a droop rate on the final performance of the intelligent cyclic A/D converters employing the standard (one-dimensional) and extended algorithms are discussed and compared in the paper.

Ciro Spataro
ADC BASED MEASUREMENTS: A COMMON BASIS FOR THE UNCERTAINTY ESTIMATION

In the last years, many Authors have dealt with the uncertainty evaluation of the measurement performed by using an analog-to-digital converter, proposing different approaches to analyze the uncertainty propagation. However, in these studies, in order to identify the uncertainty sources, different sets of parameters are used, and, often, it is not considered that the various uncertainty sources have different modalities of propagation. Obviously, this implies that the various proposed approaches are not directly comparable. One of the main reasons which has caused this situation is the coexistent of various Standards concerning the characterization of the analog-to-digital converters. Therefore, the manufacturers of converters have got a large arbitrariness in choosing and measuring the parameters which specify the performances of their products. With the aim to overtake these limitations and to suggest a common basis, in this paper, we identify, among the large number of parameters proposed by the various Standards, a minimum set of figures of merit which allows a correct uncertainty evaluation of a generic measurement performed by using an analog-to-digital converter. In order to verify the effectiveness of the proposed approach we applied the method to real measurements and compared the results with the ones obtained by means of experimental tests.

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