Nicola Giaquinto

FFT test of A/D converters to determine the integral nonlinearity

In 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.

Digital signal processing techniques for accurate ultrasonic sensor measurement

Abstract Digital signal processing techniques for obtaining high accuracy in ultrasonic distance measurements are presented. The proposed methodologies employ a suitable time–frequency representation (Wavelet Transform or Short Time Fourier Transform) to extract the envelope of the reflected pulse echo, together with a suitable pulse detection algorithm (threshold or correlation) for time-of-flight estimation. A complete meteorological characterization of the methods, in terms of systematic and random errors, is achieved, demonstrating the high overall performance.

An acoustic method for soil moisture measurement

The paper deals with the problem of measuring the soil moisture by an accurate, in-situ, real-time method. Like this a mathematical model which describes a functional relationship between water content of agricultural soil and velocity of propagation of sound waves is analyzed in systematic way. After studying the conditions that guarantee the applicability of proposed model, the velocity curves relevant to different kinds of soils are determined. This model seems to be promising for moisture soil measurements in greenhouse where the soil characteristics are well known but further investigation are necessary.

A New Method for Detecting Leaks in Underground Water Pipelines

In most water distribution systems, a fairly sizable amount of water is lost because of leaks and faults in pipes. For this reason, the individuation of leaks is extremely important for the optimization and rationalization of water resources. However, the techniques and methodologies that are currently used for the individuation of leaks, despite being universally accepted, are extremely time-consuming and require highly-experienced personnel. Additionally, such techniques become unreliable and ineffective when the measurements are not performed in specific operating conditions of the pipe (e.g., high water pressure). On this basis, in this paper, a time domain reflectometry (TDR)-based system for the non-invasive detection of leaks in underground metal pipes is presented. Not only does the adoption of the developed system leads to accurately pinpoint the leak, but it also allows to dramatically reduce the required inspection times. The TDR-based system for leak detection is described in detail (with particular attention to the measurement principle behind the method and to the methodology). Furthermore, a strategy for enhancing the accuracy in pinpointing the leak is addressed. The proposed system is validated through experimental campaign that consisted in carrying out a leak-detection survey through the traditional methods and through the proposed method.

SCADA/HMI Systems in Advanced Educational Courses

This work gives a detailed description of some laboratory practices about SCADA/HMI systems developed for didactic purposes for various undergraduate courses at the 1st Engineering Faculty of Polytechnic of Bari, Department of Electrics and Electronics (Italy); they consider the use of National Instruments LabVIEWreg with the associated data logging and supervisory control toolset (DSCreg) to develop the SCADA/HMI portion (operators interface and data logging) of a software simulated industrial plant consisting of a vessel with charge and discharge proportional valves, a heating/cooling element, a level sensor and two flow rate sensors. The control of this plant can be done in two different ways, according to the difficulty level of the practice: by way of a LabVIEW VI or by way of a ladder program written with RSLogix 5/500 and emulated by RSLogix Emulate 5/500 (both are Rockwell Softwares products, the first being the ladder software development environment for PLC-5/SLC500 family of industrial programmable logic controllers (PLCs) from Allen Bradley and the second being the related software emulator).

Functional Evaluation of Handgrip Signals for Parkinsonian Patients

This paper concerns the problem of recording and analyzing biomedical data that characterize the motor activities of the limbs in patients suffering from Parkinsons disease. The aim of this paper is the individuation of suitable parameters that are useful for detecting subjects affected by Parkinsons disease and revealing the state of the patient. Hence, a simple and inexpensive system that measures the force of palmar grip is presented and discussed, and a suitable software protocol that is able to record and manage the acquired data is developed. Finally, some biomedical parameters have been identified, characterizing the motor activities of limbs. The study of these parameters and the analysis of the correlations between the acquired data permit taking out useful information and details about the objective evaluation of Parkinson pathology, taking into account the metrological characteristics of the used measurement system

INL reconstruction of A/D converters via parametric spectral estimation

The work presented in this paper builds on previous research done by the authors detailing a novel procedure for obtaining a very fast measurement of the integral nonlinearity of an 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).

Testing and optimizing ADC performance: a probabilistic approach

A novel approach to the topic of analog-to-digital converter (ADC) characterization is proposed. The key idea is to describe the behaviour of the device via a suitable conditional probability function, estimated through a modified version of the popular histogram test. Any traditional figure of merit for ADCs can be accurately evaluated from the proposed probabilistic characterization. Besides, this allows one to optimize the ADC overall performance, determining the best allocation of the output reconstruction levels. The parameters of the modified histogram test are determined as a function of the desired accuracy. Finally, computer simulations illustrate the performance of the method.

Microwave TDR for Real-Time Control of Intravenous Drip Infusions

This paper explores the use of a microwave-reflectometry-based system for the automatic control and real-time monitoring of the flow and of the liquid level in intravenous (IV) medical infusions. In medical and hospital contexts, other kinds of devices, mainly based on the optical detection and counting of the infusion drops, are used. Nevertheless, the proposed system is aimed at circumventing some typical drawbacks deriving from the adoption of these traditional methods, thus allowing an efficient alternative for automatically monitoring the instantaneous flow of IV medical solutions. To this purpose, the proposed system combines microwave time-domain reflectometry (TDR) measurements with a noninvasive sensing element (i.e., strip electrodes directly attached to the external surface of the infusion bottle). Experimental results confirm that, by using low-cost portable TDR devices, the solution flow process can be controlled with acceptable accuracy. Therefore, the proposed method can be regarded as a promising control tool for in-hospital patient management as well as for telemedicine programs.

A TDR-based system for the localization of leaks in newly installed, underground pipes made of any material

In this paper, a time domain reflectometry-based system for locating leaks in underground pipes (made of any material) is presented. The proposed system simply requires that a biwire should be attached to the pipe (all along its length), at the time of installation. Basically, the biwire acts as a permanent sensing element that can be connected to the measurement instrument whenever it is necessary to check for the presence of leaks. It is worth emphasizing that such a simple and low-cost system could tremendously facilitate leak detection not only in water distribution systems but also in wastewater/sewer pipelines. The proposed system was validated through measurements on a newly installed pilot plant, in which a leak was intentionally provoked.