Implementation and Performance Analysis of a Digital BPSK Demodulation Technique for Galvanic-Coupling Communication

This paper presents a digital demodulation technique for use in galvanic coupling intra-body communication (GC IBC) with BPSK-modulated signals at low frequencies (below MHz). The technique relies on a direct oversampled acquisition of the BPSK- modulated signal with an analogue-to-digital converter (ADC) associated with an original digital processing algorithm to extract the demodulated data from the acquired samples. The originality of the solution resides in the digital processing algorithm which combines several mechanisms to fully exploit the redundancy present in the collected samples in order to provide a high degree of robustness, while maintaining a low level of complexity compatible with efficient implementation in a microcontroller. Simulation and measurement results are presented, confirming the robustness of the proposed solution. In particular, hardware measurements carried out under controlled conditions demonstrate very good performance, with a Bit Error Rate (BER) below 3 × 10−5 for a signal with a Signal-to-Noise Ratio (SNR) of −5 dB. The proposed solution is also validated under real conditions with a GC communication realized through the back muscle of a fish, resulting in a BER < 2.5 × 10−6.