DIGITAL STHETHOSCOPE

DIGITAL STETHOSCOPE

Ø OBJECTIVE:

To design, develop and implement an intelligent stethoscope using LabVIEW for health care applications.

Ø OVERVIEW:

•  To design and develop a system to acquire PCG signals using a stethoscope.
•  To extract features from PCG signals and display in LabVIEW.·
•  To develop intelligent Support Vector Machine algorithm for effective diagnosis.
•  To develop intelligent stethoscope for multifarious health care applications.

Ø SENSOR:

Used an ordinary stethoscope with a Calibrated electret condenser microphone on the other end.

Ø GAIN SETTING

We had a huge problem while setting the gain for the circuit.Initially while designing the circuit we calculated and set that to be 21.But practically,we faced a few problems.

HARDWARE REQUIREMENTS

·         Stethoscope

·         Calibrated Electret Microphone

·         Operational Amplifier(IC 741)

·         Potentiometer

·         Resistors

·         Capacitors

·         Battery

·         Monojack

·         NI myRIO 

SOFTWARE REQUIREMENT

·         LabVIEW software

Ø LPF CHARACTERISCTICS:

We built an LPF with 1000Hz at first.But since we didn’t get the results as we expected ,we included a resistance of 1.5K so that the cut off frequency decreases from 1000 to 500Kz.

Output Signal

Ø CONNECTIONS:

We really had a tough job in getting an exact output without noise.The main reason behind this was loose connections.Even though it was a simple circuit it took time for us to study through it and analyse.But once when we got the output at first stage (NIA-I) itself it was a great success for us.Our signal conditioning unit consists of:

o   Pre-amplifier with a gain of 21 

o   Low pass filter

o   Variable amplifier with a gain of 4- 21

·        Pre amplifier amplifies the electrical signal acquired from the microphone in order to obtain desired output.

·        The obtained amplified signal is fed to the low pass filter of cut off frequency 500Hz to remove ambient noise signals.

The filtered signals are then amplified by a variable gain amplifier in order to achieve desired gain which may vary for each subject

FLOW OF PROPOSE ALGORITHM

The heart sounds were really clear and we observed it over DSO.We found the heart sound variations and it was a huge success for us because getting a heart sound alone in that noisy area was a difficult thing.

But when we connected the output to PC through monojack to display in LabVIEW,we really couldn’t achieve it.But we managed to get it

The LabVIEW software from National Instruments is used to provide further signal processing such as digital filtering, feature extraction, classification and graphical interface for controlling certain parameters. Signal processing techniques in LabVIEW involves the following steps:

                                                                    

READ PCG SIGNALS- Signal Acquisition and processing is done for the PCG signal

FILTERING-.The signal is filtered, normalized and scaled for further analysis.

FEATURE EXTRACTION –Feature extraction deals with extraction of information `that is relevant from the signal. The identified features which holds information best for classification