Figure 12
From: Enabling Covert Body Area Network using Electro-Quasistatic Human Body Communication
(a,b) EQS-HBC signal excitation simplified circuit model with the forward path components lumped to a single impedance (Zbody). Cband refers to the series coupling capacitor at the output of the transmit device along with the interfacing copper electrode band capacitance formed between the transmit device and the human body, DTx denotes the on-body distance for signal transmission from the transmit device to the feet, which would give the voltage drop across the body (Vbody). (c) Power Spectral Density (PSD) of a broadband transmitted signal occupying the complete bandwidth from DC up to the data rate (DR). Bottom: PSD of the broadband transmitted signal after dc-balancing with 8b/10b encoding scheme. (d) Electric field developed across the body at a low frequency of 1 KHz is orders of magnitude lower than the IEEE defined threshold of 2.1 V/m (controlled environment) or 0.701 V/m (general public)39,40, for varying forward path body impedances (emulating different skin conditions) in the range of few Kiloohms. (e) Even with varying frequencies, the developed E-field across the body is orders of magnitude lower than the IEEE defined thresholds39,40 at those frequencies.
