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Abstract: A "physiological signal simulator" is a testing and teaching device. The following five physiological signals are simulated: ECG, arterial blood pressure wave, pulmonary artery pressure wave, airway pressure signal, and heart sound waveforms or phonocardiograms. The design uses MC68HC11 platform and allows for simultaneous display of up-to five signals in a typical oscilloscope. Also, the system allows the user to adjust frequency, and pressure values. The design is unique because it seeks to trade off low cost, tedious design for high cost alternatives. Introduction:Primarily from 1950's physiological parameters were measured and/or monitored using electronic instrumentation to diagnose diseases, and to evaluate and monitor a person's health. Simulator of physiological signals is useful as a teaching aid and as "proof of performance" testing devices. The signals simulated, the hardware and software requirements, the economic factors make each simulator to be unique. Theory:
Five signals that are important to be monitored in the cardiovascular and related systems are electrocardiogram (ECG), arterial blood pressure, pulmonary artery pressure, airway pressure, and phonocardigram (PCG).
Signals Control Specifications:
Hardware Description: Stand Alone Physiological Signal Simulator Circuit Software Description: The system consisted four main parts: Information Acquisition: Acquire and properly store user information about the number of graphs, the type of graphs, the type of adjustments and, information regarding navigation. Display Dispatcher: The algorithm that based on the user requests, properly sends data to the display. Controls: Frequency, amplitude, and other controls corresponding to signals under consideration. Robust Interface: Allowing for flexible user navigation, and options. The hardware platform has already been selected. The selection of HC11 will require us to implement the system using its assembly language.
The user input was received from five simple switches which were polled. For instance, in state two the user information is handled as follows:
Design Assessment: Here are items we were able to implement: However, there were series short comings. Epilogue:
Although the project had many learning opportunities, it was not a successful useful product and was incomplete. Lack of end-product vision, proper research, proper division of labour and resources contributed to our not so "successful" project. However, we received a B+, because we demonstrated great independence and persistence in tackling problems. We understood the elements such as cost, time, demand, and intangibles that are involved in product design and implementation. We understood the gab between an idea and product, the need for design and documentation before implementation, and the grave importance of properly defining the scope and vision of the end product.
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