MEASUREMENT OF NONSTANDARD LEADS FOR ECG SIGNALS

V diplomski nalogi predstavljamo programsko in strojno rešitev za nestandardno merjenje elektrokardiografskih (EKG) signalov. Z opisano rešitvijo želimo preveriti, ali je možno hitrejše, preprostejše in nemoteče merjenje EKG-signalov z manjšim številom elektrod, ki so v smislu klinične prakse postavljene na nestandardnih mestih (npr. prstih). Zasnova strojne opreme temelji na treh delih. Prvi predstavlja vezje ADS1298 proizvajalca Texas Instruments, ki opravlja funkcijo zajemanja in ojačenja analognega EKG-signala ter analogno-digitalno (AD) pretvorbo. Drugi je mikrokrmilnik PIC32MX proizvajalca Microchip, ki skrbi za krmiljenje vezja ADS1298 in prenos podatkov preko vmesnika USB na osebni računalnik. Tretji del je osebni računalnik, kjer se podatki obdelajo in shranijo. Programska rešitev je sestavljena iz dveh delov, in sicer kode za mikrokrmilnik PIC32MX, ki skrbi za komunikacijo z ADS1298 in osebnim računalnikom, ter programske opreme na osebnem računalniku, ki skrbi za izris EKG-signala ter obdelavo in shranjevanje podatkov. Z opisano rešitvijo smo uspeli zanesljivo izmeriti EKG-signal z dvema elektrodama, ki sta nameščeni na nestandardnih odjemnih mestih, npr. na prstih rok. Cilj nemotečega in hitrega merjenja je dosežen delno, saj pri krajših razdaljah med elektrodama in kratkotrajnih stikih meritve niso bile zelo zanesljive. Opisano rešitev bi bilo možno izboljšati z izdelavo analognega nizkošumnega predojačevalnika, boljšega algoritma za filtriranje signala ter uporabo kakovostnejših elektrod.This diploma thesis presents a hardware and software solution for non-standard measurements of electrocardiographic (ECG) signals. The purpose of proposed design is to assess the feasibility of measuring the ECG signals faster, easier, unobtrusive and with less electrodes that are placed at non-standard locations compared to established clinical practice. Hardware consists of three parts: semiconductor circuit ADS1298, made by Texas Instruments, is responsible for acquisition, amplification, and digitalization of analog ECG-signals. Second part is microcontroller PIC32MX, made by Microchip. It is responsible for management of ADS1298 and data transfer through USB interface to a personal computer. Third part is personal computer where acquired data is processed and stored. Software solution consists of two parts: a code that is responsible for communication with ADS1298 and is executed inside microcontroller PIC32MX, and software at the personal computer level to visualize ECG signals, and process and store the acquired data. Presented solution enabled reliable measurement of ECG-signals, when two electrodes were placed at non-standard locations, such as fingers of both arms. The goal of less obtrusive and faster measurments was partially achieved, because measurements were not very reliable when distances between electrodes were short or contacts with electrodes were of short duration. The solution could be enhanced by constructing a low-noise preamplifier, by designing better algorithms for signal filtering and by use of higher quality electrodes