Battery-Powered Receiver for Characterization of Capacitive Intrabody Communication Channel

Prijenos signala ljudskim tijelom jedna je od mogućih tehnologija za povezivanje senzorskih čvorova i baznih stanica u BAN mrežu. Postoje dva načina spajanja na ljudsko tijelo obzirom na položaj elektroda: galvansko i kapacitivno spajanje. Kod kapacitivnog spajanja glavni put signala ostvaren je kroz ljudsko tijelo, a povratni put je ostvaren kapacitivnom vezom između elektroda, koji može uključivati i okolinu. U ovom diplomskog radu dana je teorijska podloga bitna za razumijevanje načina rada realiziranog sustava te je dan pregled do sada provedenih istraživanja. Naglasak je na arhitekture prijamnika u sustavima za prijenos signala ljudskim tijelom. Arhitektura sustava za mjerenje snage primljenog signala zasniva se na odvojnom pojačalu BUF602ID, logaritamskom pojačalu AD8310, mikrokontroleru STM32WB55CG, anteni za povezivanje Bluetoothom te regulatoru napajanja TPS73633. Konačni rezultat je baterijski napajano mjerilo snage primljenog signala realizirano na dvije tiskane pločice. Prva tiskana pločica temelji se na odvojnom pojačalu i služi za smanjenje utjecaja impedancije između prijamnih elektroda na rezultate mjerenja. Druga tiskana pločica je mjerilo snage primljenog signala. Također, u radu je napisana programska podrška za akviziciju podataka s izlaza logaritamskog pojačala preko ugrađenog AD pretvornika na mikrokontroleru. Razvijena je i programska podrška za povezivanje pločice i osobnog računala putem Bluetootha. Za kraj su prikazani rezultati mjerenja karakteristika razvijenog sustava, i to mjerenje snage primljenog signala bez pločice odvojnog pojačala i mjerenje snage primljenog signala s povezanom pločicom odvojnog pojačala.Intrabody communication is one of the possible technologies for connecting sensor nodes and base stations in the BAN network. There are two ways of connecting the electrodes to the human body, depending on their position: galvanic and capacitive method. In capacitive method, the main path of the signal is realized through the human body, and the return path is realized by the capacitive connection between the electrodes, which can include the environment. In this master thesis, the theoretical basis relevant for the implemented system is given, as well as an overview of the research carried out so far. Emphasis is placed on receiver architectures in intrabody communication systems. The architecture of the system for measuring the power of the received signal is based on the buffer amplifier BUF602ID, logarithmic amplifier AD8310, microcontroller STM32WB55CG, Bluetooth antenna, and voltage regulator TPS73633. The result is a battery-powered signal strength meter realized on two printed circuit boards. The first printed circuit board is based on a buffer amplifier and is used to reduce the influence of the impedance between the receiving electrodes on the measurement results. The second printed circuit board is used as a received signal strength meter. Also, the firmware for data acquisition from the output of the logarithmic amplifier via the built-in analog-to-digital (AD) converter on the microcontroller was written. Firmware for connecting the board and a personal computer via Bluetooth has also been developed. Finally, the results of measuring the characteristics of the developed systems are presented, namely the measurement of the received signal power without the buffer amplifier board and the measurement of the received signal power with the buffer amplifier board connected between the source and the second printed circuit board