TI's TMS320C5515 DSP Evaluation Module together with TI's digital stethoscope analog front-end module make up the new C5505 DS Medical Development Kit (MDK) provides developers access to a development tool set that offers a complete signal chain solution along with software to save months of development time and for portable patient monitoring applications that demand battery efficiency.
The main elements of a Digital Stethoscope are the sensor unit that captures the heart and lung sounds (also known as auscultations), digitization, and digital processing of the auscultations for noise reduction, filtering and amplification. Algorithms for heart rate detection and heart defect detection may also be included.
Power and Battery Management are key in this ultra-portable diagnostic tool, where key design considerations are ultra-low power consumption and high efficiency driven by the need for extended battery life, and high precision with a fast response time allowing quick determination of the patient's health status. Additional requirements may drive the need for recording the auscultations, cabled or wireless interfaces for transmission of the auscultations. Also, to enable ease of use, features like touch screen control and display backlighting are key to usability of the device. Adding all these features without significantly increasing power consumption is a huge challenge. Texas Instruments portfolio of Processors, Instrumentation and Buffer Amplifiers, Power and Battery Management, Audio Codecs, and both wired and wireless interface devices provides the ideal tool box for Digital Stethoscope applications.
The common core subsystems of a Digital Stethoscope are:
- Analog Front-End/Sensor Interface and Codec
Auscultations signal input is amplified and then digitized by the Audio Codec. Auscultations signal after being digitized and subjected to signal processing, is converted to analog and sent to the stethoscope earpiece.
Processors capable of executing all of the digital stethoscopes signal processing including key functions such as noise reduction, algorithms for heart rate detection, and heart defect detection while maintaining a very low constant current draw from the battery are good fit. The ability to control interfacing with memory and peripheral devices is also helpful. Given the nature of the device, processors that can manage the digital display and keyed functions allowing auscultation waveforms to be displayed and manipulated without additional components are ideal.
- Data Storage and Transmission
The auscultations can be recorded on MMC/SD card, or on a USB device. It can also be transmitted via wireless capability such as Bluetooth.
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