Electric field measurement for biomedical application using GNU radio

Abstract

The authors are studying a technique to measure inside of the human body by utilizing simple electromagnetic method. An antenna as small as a few centimeters square generates electric field at Radio Frequency (RF), and the same type of antenna measures electric field intensity where two antennas are located 15 to 50 cm apart from each other. Although the method does not provide fine resolution because of the principle, it has such advantages as safe and economy so that it can be applied to medical screening devices and welfare equipment. Experiments and simulations had been performed to reveal basic characteristics of the method. One of the technical issues suggested by the experiments was instability of the raw receiving signals. Because signal changes caused by human body were small, improvement of the stability was essential for medical application. This paper reports preliminary experiment where the human body was measured by a new experimental system. The previous experimental system consisted of a general-purpose spectrum analyzer that only measured amplitude of input signal in a certain frequency range. The new measurement system, introduced in this paper, consisted of a GNU Radio compliant peripheral and GNU Radio software. GNU Radio is an open source project where user can build special purpose receiver and transmitter in conjunction with a simplified peripheral. The measurement results indicated advantages of the new experimental system with GNU Radio. © 2011 Springer-Verlag.