Marcello Salmeri, Arianna Mencattini, Giulia Rabottino, Roberto Lojacono
SIGNAL-DEPENDENT NOISE CHARACTERIZATION FOR MAMMOGRAPHIC IMAGES DENOISING

The paper deals with the noise characterization under the assumption of a heteroscedastic signal–dependent noise model in the context of medical imaging. In particular, in this kind of application, a sophisticated noise variance estimation algorithm is applied using robust estimators and nonlinear regressions. A direct relation between noise variance and pixel intensity values is obtained and used within a multiresolution denoising algorithm, performed by Wavelet Thresholding (WT). We will provide results of the noise estimation, by applying the proposed method to mammographic images.

A. Cataldo, G. Monti, E. De Benedetto, G. Cannazza, L. Tarricone, L. Catarinucci
ON THE USE OF A RELIABLE LOW-COST SET-UP FOR CHARACTERIZATION MEASUREMENTS OF ANTENNAS

In this paper, a low-cost time domain-based approach to antenna characterization is presented. The goal is to prove that time domain-based antenna measurements, after appropriate processing, represent an accurate and more practicable alternative to the universally accepted (yet highly expensive) antenna measurements in anechoic chamber, and provide information just as complete. Measurements on two commercial antennas are carried out in the time domain (in a noncontrolled environment) and in the frequency domain (in an anechoic chamber): experimental data obtained from the two approaches are compared in terms of Return Loss. Results show that reliable results can be extracted from time domain data, and that a good insight into the antenna characteristics can be obtained even without using highly expensive facilities.

U.Pogliano, B. Trinchera, G.Bosco and D.Serazio
DESIGN OF A THERMAL WATTMETER IN THE AUDIO FREQUENCY RANGE

This paper describes the development of a system for the measurement of power in the audio frequency range. Flexible units operating with a strategy based on the evaluation of rms quantity by a thermal method have been constructed. For each unit of the set-up, measurements and a preliminary characterization have been performed and estimation of the uncertainty will be discussed.

Marko Jurčević, Hrvoje Hegeduš, Roman Malarić, Hrvoje Zeba
GENERIC ENVIRONMENT FOR INTERNET-ENABLED CALIBRATION SERVICES

Since many of the available digital instruments are provided with some communication interfaces and the internet-enabled metrology is rapidly developing in the recent years, it is possible to create an actual remote calibration system with remote control capabilities. This approach addresses a wide range of possible applications that allows driving many kinds of different devices and can be easily upgraded. This paper focuses on some of the solutions for security problems regarding remotely executed internet-enabled calibration processes.

Valeriu David, Ionut Nica, Alexandru Salceanu, Octavian Baltag
THE MEASUREMENT OF RADIOFREQUENCY ELECTROMAGNETIC FIELDS IN SOME SPECIAL PLACES

In this paper we present the levels of electromagnetic fields, due to the radiofrequency communication systems, in some special places as: hospitals, laboratories in the city and houses situated near broadcastings towers. Comparative measurements were made, using some types of near field probes and antennas in 90 MHz ÷ 2700 MHz frequency domain. We also determined both the root mean square – r.m.s. values of the three perpendicular components of the electric fields and the r.m.s. values of the maximum electric field vector, and then we compared the results. The aim of our measurements is the evaluation of the electromagnetic fields levels generated by communication systems, because of their possible interaction on the human body, electronic medical equipment and generally electrical devices.