ECG-Noise-filter

Abstract :

Noise reduction in ECG signal using Finite Impulse Response(FIR) filter
         ~The electrocardiogram (ECG) signal is non-stationary
         electrical signals from the heart characteristically 
         precede the normal mechanical function and monitoring
         of these signals has great clinical significance.

Motivation:

         ~The heart rate analysis from an ECG is crucial in
         assessing the health condition of an individual. 
         
         ~But the measured ECG tend to have noises such as
         the 50Hz interference and the DC.  
         
         ~These noises make the detection of peaks inaccurate
         which in turn make the detection of heartrate inaccurate.
         
         ~Thus, removing the noises from the ECG is pertinent
         for the proper analysis of the ECG signal.
         
         ~We have used FIR filter to achieve filtration of ECG signal.

System description with application :

         ~The Electrocardiogram (ECG) machine with 4 terminal wires is
         an electrogram of the heart which is a graph of voltage versus time
         of the electrical activity of the heart using electrodes placed on the skin.
         These electrodes detect the small electrical changes.
         
         ~But the signal have power line interference which have 50Hz frequency
         and DC which make the detection of heartrate inaccurate.
         
         ~The finite impulse response (FIR) filter is created to remove the
         50Hz interference as well as the DC from the signal. 
         
         ~We used bandpass filter  for the calculation of impulse response of
         the desired frequency response created and Hamming window for normalising
         the impulse response which is used for convolution of ECG signal and impulse response. 

For the values of ECG signal passed to the system -> Filtered signal values that can be displayed is returned

Methodology :

        ~FIR filters are digital filters with finite impulse response.
        
        ~They are also known as non-recursive digital filters because of their
        inherent stability when implement in non-recursive form, the ease with 
        which one can attain linear phase and more stable which cant be achieved in IIR filter.
        
        ~This filter doesn’t depend on past samples of input along with past output like the IIR filter.
        
        ~Bandstop filter is a combination of lowpass and highpass filter 
        which can block or at least severely attenuate a band of frequencies within 
        the two cut-off frequency points specified and allow frequencies other than that.  
        
        ~The Hamming window is a taper formed by using a weighted cosine 
        which reduces the ripple on either side of the peak.
        
        ~Then, the ECG signal and impulse response is passed to a function 
        that does convolution and returns the filtered signal.