Design of a wireless stethoscope

Project (M.S., Electrical and Electronic Engineering) -- California State University, Sacramento, 2012.A stethoscope is a primary device used by medical doctors. It is used to listen to a patient???s heart and lung sounds. Acoustic, electronic, and wireless stethoscopes are commercially available. A problem with the acoustic and electronic stethoscopes is that harmful germs can be spread to other patients as the doctor uses the same stethoscope from patient to patient. Also, the doctors may get infected with the germs as they sit close to the patients they are examining.\ud A wireless stethoscope, consisting of a chest piece and a separate head set, can be used to reduce the spread of germs, because the doctors do not have to sit as close to the patients as when using the acoustic or electronic stethoscopes. But due to their cost, they are rarely used, and patients are still in danger of getting infected as the doctors use the same chest piece (transmitter module) from patient to patient. A lower-cost wireless stethoscope that is more affordable, allows providing a separate transmitter module to each patient, and perhaps allows the chest piece to be disposable, is proposed. \ud The design requirements are that the device has to provide clear sound, have a range of wireless transmission of 10-15 feet, and have a cost lower than that of the wireless stethoscopes that are currently available in the market. The design uses a microphone, low voltage amplifiers, analog RF transmitter, analog RF receiver, and earphones. The microphone is a transducer that converts heart/lung sounds to an electrical signal. This converted electrical signal then is amplified and transmitted. The receiver receives the transmitted signal and then amplifies the signal. The amplified signal then is heard through earphones. The signal-to-noise ratio, frequency response, and cost of the design are compared to the existing acoustic, electronic and wireless stethoscopes.\ud The device developed does not provide sound as clear as that of the electronic stethoscope, and the noise increases as the distance increases between the chest piece and the head set. The frequency response of the device is not satisfactory, as it is not flat for heart and lung sounds (30 ??? 1,000 Hz). Without considering manufacturing costs, the cost of the device is less than the cost of the wireless stethoscope and less than the average cost of the electronic stethoscope but more than the average cost of the acoustic stethoscope.Electrical and Electronic Engineerin