C. Offelli

Bio: C. Offelli is an academic researcher from University of Padua. The author has contributed to research in topics: Frequency domain & Discrete Fourier transform. The author has an hindex of 13, co-authored 26 publications receiving 1323 citations.

Digital time-of-flight measurement for ultrasonic sensors

Abstract: Ultrasonic sensor measurements are mostly based on the determination of the time of flight (TOF). The authors present the development of a digital algorithm for pulse-echo measurement applications, based on the use of a cross-correlation function to determine the TOF. Some experimental results are presented, and the possibility of realizing a low-cost real-time measurement system is considered. >

Interpolation techniques for real-time multifrequency waveform analysis

Abstract: It is well-known that in discrete-Fourier-transform- (DFT-) based waveform analysis of multifrequency signals, spectral parameter accuracy can be increased by windowing the time samples and interpolating the DFT coefficients. It is shown that some relationships used in interpolation are affected very little by the number of processed samples, so that only the characteristics of the analyzed signal and the required accuracy affect the choice of this parameter. In particular, this makes the approach well suited for real-time analysis of signals with slowly time-varying spectra. Polynomial approximations of some relationships reduce the processing effort and, allow a greater freedom in the choice of the window functions, improving both accuracy and frequency resolution. >

A Web-based distributed virtual educational laboratory

Abstract: Evolution and cost of measurement equipment, continuous training, and distance learning make it difficult to provide a complete set of updated workbenches to every student. For a preliminary familiarization and experimentation with instrumentation and measurement procedures, the use of virtual equipment is often considered more than sufficient from the didactic point of view, while the hands-on approach with real instrumentation and measurement systems still remains necessary to complete and refine the student's practical expertise. Creation and distribution of workbenches in networked computer laboratories therefore becomes attractive and convenient. This paper describes specification and design of a geographically distributed system based on commercially standard components.

The influence of windowing on the accuracy of multifrequency signal parameter estimation

Abstract: The author investigates the influence of windowing on the accuracy of a frequency-domain procedure suitable for real-time estimations of multifrequency signal parameters. Imposing very weak assumptions about the statistical description of the noise, simple and accurate expressions for the estimator variances are established. They allow both the evaluation of the result accuracy and the design of the measurement procedure. Simulation results confirm the validity of the presented analysis. >

A client-server architecture for distributed measurement systems

Abstract: This paper describes a client-server architecture for the remote control of instrumentation over the Internet network. The proposed solution allows multi-user, multi-instruments sessions to be obtained by means of a queueing process and provides instrument locking capability. Client applications can be easily developed by using conventional high-level programming languages or well-assessed virtual instrumentation frameworks. Performance tests are reported, which show the low overhead due to network operations with respect to the direct control of the instruments.

IEEE Standard for Terminology and Test Methods for Analog-to-Digital Converters

Abstract: The design process will be affected in several ways. Without careful attention, the ADC interfacing could produce substandard results. Additional devices such as terminators, attenuators, and delay lines may need to be added to match signal levels and to provide signal isolation. The standard will also help incorporate evaluation considerations and test methods into the design and implementation processes.

Virtual and remote labs in education

Abstract: Laboratory experimentation plays an essential role in engineering and scientific education. Virtual and remote labs reduce the costs associated with conventional hands-on labs due to their required equipment, space, and maintenance staff. Furthermore, they provide additional benefits such as supporting distance learning, improving lab accessibility to handicapped people, and increasing safety for dangerous experimentation. This paper analyzes the literature on virtual and remote labs from its beginnings to 2015, identifying the most influential publications, the most researched topics, and how the interest in those topics has evolved along the way. To do so, bibliographical data gathered from ISI Web of Science, Scopus and GRC2014 have been examined using two prominent bibliometric approaches: science mapping and performance analysis. Display Omitted Laboratory experimentation plays an essential role in engineering and sci-entific education.Virtual and remote labs are emerging as a valuable alternative to conven-tional hands-on labs.This paper analyzes the literature on virtual and remote labs from 1993 to 2015.4405 records retrieved from ISI Web of Science, Scopus and GRC2014 are processed.Two bibliometric approaches are applied: performance analysis and science mapping.

An ultrasonic sensor for distance measurement in automotive applications

Abstract: This paper describes an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. A constrained optimization technique is employed to obtain reflected pulses that are easily detectable by means of a threshold comparator. Such a technique, which takes the frequency response of the ultrasonic transducers into account, allows a sub-wavelength detection to be obtained. Experimental tests, performed with a 40 kHz piezoelectric-transducer based sensor, showed a standard uncertainty of 1 mm at rest or at low speeds; the sensor still works at speeds of up to 30 m/s, although at higher uncertainty. The sensor is composed of only low cost components, thus being apt for first car equipment in many cases, and is able to self-adapt to different conditions in order to give the best results.

The interpolated fast Fourier transform: a comparative study

Abstract: The properties of five interpolating fast Fourier transform methods (IFFT) are studied with respect to their systematic errors and their noise sensitivity, for a monofrequency signal. It is shown that windows with small spectral sidelobes do not always result in a better overall performance of the IFFT and that time-domain estimators can be more efficient than the IFFT methods analyzed. It is also, shown that time-domain techniques have a lower Cramer-Rao lower bound than the IFFT methods, which can result in more efficient estimates. >