1,721,023 research outputs found
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
A CNN-based passive optical range finder for real-time robotic applications
No full textThe paper presents a new cellular neural network cellular neural network (CNN) for real-time stereo vision, useful as a passive optical range finder for autonomous robots and vehicles. The stereo matching as energy minimization is discussed, and former neural approaches to the problem are analyzed. Experimental results with the new CNN both with synthetic and real images are reported, demonstrating the performance of the system
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
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)
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
Metrological qualification of data acquisition systems
No full textThe paper treats the metrological qualification of data acquisition systems illustrating general ideas and a practical test method. The necessity of an improved industrial standard for users and manufacturers is discussed, remarking the convenience of a model identification approach. Following this line of reasoning, a new test method (modified statistical domain analysis) for simultaneous measurement of nonlinearity, amplitude noise, time noise and global error of a digitizer is presented, putting in evidence that it provides identification and validation of a first-order error model of the system. This is obtained via ct single acquisition of a reference sinusoidal signal and a unique consistent scheme of computations. Simulation and experimental results illustrate the practical advantages and limits of the test, the latter emerging at the higher frequencies, when the adopted memory-less model of the ADC is no more valid. (C) 1998 Elsevier Science B.V. All rights reserved
Introductory notes for the Acta IMEKO Special Issue on the 40th Measurement Day jointly organised by the Italian associations GMEE and GMTT
No full textCoupling dithering and static linearization in a/d converters
No full textThis paper presents a study of the performance attainable by combining two different methods of linearization algorithms for A/D converters: dithering (which removes errors due to quantization) and static look-up table (which removes errors due to INL). The theory and the simulation results show two very important facts, i.e.: (i) the amplitude of the dither signal must be chosen according to the INL of the converter, and should be greater than the usual value of 0.5 LSB rms; (ii) using both the linearization techniques allows one to attain (in absence of other sources of error) an arbitrary high number of effective bits, proportional to the logarithm of the averaged samples
FFT test of A/D converters to determine the integral nonlinearity
No full textIn this paper, the use of the fast Fourier transform (FFT) test to measure the integral nonlinearity (INL) of analog-to-digital (A/D) converters is examined. The derived INL is a linear combination of Chebyshev polynomials, where the coefficients are the spurious harmonics of the output spectrum. The accuracy of the test is examined theoretically, in simulations and in practical devices, particularly for the critical (and typical) case when sudden jumps are present in the actual INL. The examined methodology appears to be very convenient when the device under test has high resolution (16-20 bits) and a smoothed approximation of the INL is sufficient, as the FFT test is in this case thousands of times faster than the customary histogram test and static nonlinearity test
Linearization of A/D converters by dither and Chebyshev polynomials
No full textThe paper illustrates a new procedure, simple and very fast, to measure and correct the linearity error in A/D converters. The method is based on the Chebyshev polynomial synthesis of the static characteristic via frequencydomain analysis, and is especially effective for dithered converters
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