Thesis - Open Access
Master of Science (MS)
The problem to be investigated within the scope of this manuscript involves the initial groundwork for eventual field telemetry of the pheasant ECG. It will consist of determining the input impedance and bandwidth requirements for the telemetry transmitter amplifier to be used. The effects if impedance loading on the ECG equivalent voltage generator with varying loads between 1 kꭥ and 100 kꭥ will be investigated. These data will be used to formulate a model of the electrode-skin interface transfer function. The ECG is accurately reproduced if the impedance is sufficiently large. Should achievement of a sufficiently high input impedance in the telemetry amplifier be impossible, it will be possible to reconstruct the original ECG at the receiver. This reconstruction will be possible through the knowledge of the amplifier and the electrode-skin interface transfer functions. The ECG will be analyzed from the point of view of the frequency domain. Digitization of the data will allow the use of the fast Fourier transform (FFT) computer algorithm. The FFT will aid in determining bandwidth, electrode-skin interface transfer function and amplifier input resistance. A truly unloaded ECG recording is not achievable, but for out purposes an input resistance of greater than 10 mꭥ will be considered sufficient. The electrode transfer function and final selection of the ECG telemetry transmitter amplifier input impedance will be accomplished by comparing frequency spectral data of simultaneously recorded waveforms for leaded and open circuit pheasant ECG’s. Determination of the above-mentioned parameters of bandwidth, input impedance and the electrode-skin interface transfer function is approached in the following manner. First, a six -channel amplifier is designed to obtain Leads I, II, and III of the pheasants’ loaded and unloaded ECG equivalent generator simultaneously. Leads I, II, and III are the leads of the Einthoven triangle. The data a.re then recorded and digitized for computer analysis by the FFT computer algorithm. This immediately brings forth two significant problems, digitization of the data for use in the FFT computer algorithm and preparation of the ECG signal for a six-channel FM recorder. The first problem can be solved through the use of an analog-to-digital converter. This entails ECG signal ampli-ficiation and impedance isolation of the FM recorder from the equivalent ECG voltage generator of the pheasant. This will be achieved by designing an amplifier with the following general characteristics; high gain; an input impedance which is carriable in steps from low to high values; high common-mode rejection ratio; flat frequency response; low noise and low output impedance. Chapter II will be devoted to selecting absolute maxima and minima for the previously mentioned amplifier characteristics.
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Number of Pages
South Dakota State University
Hutchens, Chriswell G., "An FFT Pheasant Egg Spectral Analysis for the Purpose of Electrode-skin Interface Modeling" (1972). Electronic Theses and Dissertations. 4714.