Revista elektron

94-99

Authors: Roberto M. Insabella, Martín Germán González

In this work, the source of the artifacts introduced in the images obtained with an optoacoustic tomography system based on the software-defined optoelectronics concept are analyzed and characterized. It is shown that the measured signals are affected both by the cylindrical geometry of the optical sensor and by electrical noise. The latter has well-defined frequencies within the spectrum caused by the electronics used in the heterodyning process of the ultrasound optical detector. A way to include these effects in simulated signals is proposed and the model is tested against measurements. The results of this work will allow the use of the deep learning technique to improve the quality of the images obtained with this type of tomographic systems.

105-111

Authors: Leonardo Martín Carducci, Ramiro Alfonso, Walter Gustavo Fano

This article presents the analog stage analysis of an extremely low frequency (ELF) magnetic field receiver. Details are described about the characterization and modeling of the antenna used, as well as the frequency behavior of the system. To achieve higher sensitivity, a coil was manufactured with a considerably high inductance (800 H), in addition to a high-gain amplification stage (88 dB). An equivalent circuit model was defined for the antenna, and its parasitic elements were determined by laboratory measurements and computational approximations. The acquisition system has a digitization stage with a sampling frequency of 100 Hz. To study its behavior against possible aliasing effects, an analysis of the analog stage in the frequency domain was carried out, determining the optimal operating conditions. Field tests of the equipment were carried out in the mountains of Villa Alpina, Cordoba, Argentina. Taking into account that the system was designed for the measurement and study of natural electromagnetic phenomena in the ELF band, the first six Schumann resonances have been successfully captured and detected.