The Design And Implementation Of Transceiver System For Galvanic Coupling Intra-body Communication Based On FPGA

Intra-body communication (IBC) is an emerging and novel short rangecommunication technique. Utilizing the conductive property of human body, IBCemploys human body as the medium for transmitting electrical signal to realize theinformation sharing among the electric devices on, in or around the body. IBC isespecially suitable for sharing information among wearable/implantable medicaldevices used to detect long-term, continuous human medical signal and is a newmeans to build body area network.The environment has less influence on galvanic coupling IBC which is moreadaptable and stable. The study is still in the initial stage and most of the results arelimited to the simulations, experiments and model exploration and the hardware sideis not in depth for galvanic coupling IBC. In this thesis, the transceiver system ofgalvanic coupling IBC is successfully designed and initially implemented on the baseof the preliminary study about the analysis of electromagnetic theory, numericalsimulation and so on for galvanic coupling IBC. Main work can be described asfollow:According to the phenomenon or characteristic of human channel found through thehuman body experiments carried out by task force in the early, the appropriate carrierfrequency is selected. And so a galvanic coupling IBC transceiver system is designedwith Continuous-phase FSK modem approach and digital demodulation based onFPGA. In the transmitter, sine waves are modulated by the use of direct frequencysynthesizer technology when the upper and lower carrier wave’s frequency are100kHz and50kHz and converted to alternating current signal applied for humantransmission though V/I circuit. In the receiver, non-coherent demodulation is used.Corresponding front-end hardware and digital demodulator are designed and so on. Sothe original digital baseband signals are correctly restored.All digital phase-locked loop is key designed to achieve bit synchronization signal forIBC based on FPGA and some indicators are presented. The ADPLL can better extractbit synchronization signals from digital baseband signal with a low symbol rate,accurately achieve regeneration of symbol and appears quick launching, small errorsand high precision. It is guaranteed for the reliability and stability of IBC system.Finally, the debugging results show that the transceiver system can reliably send andreceive data at5kbit/s on different parts of the body or among the people in theexperiments of IBC.In conclusion, the design of galvanic coupling IBC transceiver system provides asuccessful experience for the development and practical application of IBCtechnology.