A. ACCATTATI S, M. SALMERI,
A. MENCATTI NI,
G. RABOTTI NO,
Visual Analyser: a Sophisticated Virtual
Measurements Laboratory for Students
University of Rome “Tor Vergata”
16th IMEKO TC4 Symposium
Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements
24, 2008, Florence, Italy
What is the software Visual Analyser: a virtual
instrumentation set running under Windows;
Purposes of Visual Analyser :didactics, research;
Visual Analyser as typical Digital Signal
Metrological Characterization of Visual Analyser
(under construction), uncertainty
Low cost Measurement instruments;
A Didactic laboratory for students;
“Low cost” hardware = PC
“Low cost” software = Visual Analyser.
Idea: deeply modify the software Visual Analyser to obtain:
Personal Computer and DSP
Using a personal computer as “no cost“ hardware…
…plus the software Visual Analyser…
= PC as a DSP based hardware on which apply the major
results of theDigital Signal Processing science;
= source code, possibility to quickly adapt the software.
Using a PC as a standard DSP platform
From the year 1990 on the computational power of a PC reached a DSP;
For this reason now it is possible to write program like Visual Analyser.
Up to the year 1990 real time elaboration of
signal implemented making use of dedicated
200.000 lines of C++ code; Windows, Linux + wine;
Windows multithreading, as commercial instruments, making possible
to run simultaneously all the simulated instruments;
No predefined library;
IEEE 80 bit Floating point;
meaningless “Rounding error” .
Low cost virtual measurement laboratory for students;
Research activities involving signal acquisition, elaboration, synthesis;
Demonstration during lessons of many important concepts;
Wave form generator
Volt Meter AC
Data log with “trigger” events
Nyquist conversion real time
24 bit support
Specific hardware supported
Cross and auto correlation
Calculus based on standard literature, the metrological characterization
depends mainly from the acquisition board;
Numerical analysis: no cancellation, no ill conditioned algorithms;
IEEE extended floating point, 80 bit 64 bit mantissa, rounding
error highly reduced;
Lack of documentation of soundcard, we are implementig an automated
procedure Based on Monte Carlo analysis to obtain metrological
characterization of Visual Analyser + soundcard.
Accattatis, Master Thesis, “Sviluppo di uno strumento virtuale real
time per La
generazione analisi ed
acquisizione dei segnali”.
S. Caldara, S.
, “Measurement uncertainty estimation of a virtual instrument”,
of Instrumentation and Measurement Technology Conference (IMTC 2000)
, Baltimore, MD, USA.
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, M. Morel, P. H. J.
, “Uncertainty estimation by the concept of
Proceedings of SPIE, the International Society for Optical Engineering
, “A Practical Approach to Evaluate the Measurement Uncertainty of Virtual
Proc. of Instrumentation and Measurement Technology Conference
, Como, Italy, May
Evaluation of the Uncertainty in Virtual Instruments”,
Transactions on Instrumentation and Measurement
, vol. 53, n. 3, June 2004.
, A. Hetman, “A Calculation of Uncertainties in Virtual Instrument”,
Instrumentation and Measurement Technology Conference
, Ottawa, Canada, May 2005.
“Propagation of uncertainty in a discrete Fourier transform
Elsevier Measurement 27
R.I. Becker, N. Morrison, “The errors in FFT estimation of the Fourier transform”, IEEE Transaction
44 (8) (1996) 2073
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