Human Body Communication In-Vivo Measurement Using Different Test Equipment

摘要

Human body communication is non-radio frequency technique of wireless body area network, wherein the human body is used as a communication medium in two coupling methods namely: capacitive and galvanic coupling. HBC is relatively new method and in full development, given the large number of scientific publishing works depending on different setup and equipment. Even that it remains controversial with no consensus in terms of propagation characteristics and behavior mechanism. This paper deals with the common used test equipment and configuration attempting to provide a complementary information about HBC channel characterization issue. For that, in vivo measurements were carried out using several assembling of equipment in different scenarios, considering the conventional inspected parameters (channel length, transverse distance and balun insertion scenarios). The measurements were conducted in both frequency and time domain using primarily spectrum/vector network analyzer and digital oscilloscope respectively. Thus, in addition to transmission losses between transceivers across the channel (calculated path loss factor), phase angle information are considered over the operating frequency band to assert the non-dispersive HBC channel nature. Further harmonic distortion effect is shown, then high transmission power for the signal of interest is attributed to HBC methods according to the calculated total harmonic distortion THD metric, even harmonics resulting from the channel non-linearity characteristics or transceivers signal/apparatus imperfections. The experimental setups highlights the important to consider the precise criteria for measurement purpose, thus leading using the most appropriate test apparatus.