1. Processing and noise
cancelation of ECG

2. Introduction

3. •What is ECG?
•How is it generated?
•What type of information
does ECG tell?
•How can we record it ?

4. What is ECG ?[1]
• Electrocardiogram (ECG)
is the physical interpretation of the electrical
behavior created by the heart muscles.
ECG
is the electrical activity of the heart

5. How is ECG generated?[2]
• Heart Cardiac cells are negatively charged.
•Losing this negativity is called depolarization which is the fundamental
electrical activity of the heart [2] .
Depolarization propagates from cell to This wave is transmitted to the entire
cell producing a wave heart producing a current
This current can be detected using
skin electrodes
Skin Electrodes are put on the surface
of the body
The result is a periodic signal called
ECG

6. P-wave : is produced by muscle Left
contraction of atria. Right
Atrium
Atrium
QRS-wave : marks the ending of atria
contraction and the beginning of ventricular
contraction
T-wave : marks the ending of ventricular
contraction.
Left Right
ventricle ventricle

7. What type of information does ECG tell? [2]
Any ECG gives two kinds of information
First Second
the duration of the electrical the amount of electrical
wave crossing the heart activity through heart muscle
decides whether enables to find
the electrical whether the parts
activity is normal of the heart are
or slow or strong or
irregular overworked.
For example
a narrow and high QRS-wave indicates a physically strong heart

8. How can we record it ?[3]
Special electrodes are put on the surface of the body as shown in the figure
After amplifying the recorded signal , the obtained ECG signal is contaminated
with different noises that must be cleared to get the best ECG .

9. ECG processing techniques
Further Analysis
-Differentiation
Filtering -Squaring Detect
Input •Bandpass filter -Windowing heart
ECG
•Adaptive Filtering -Statistical Variance diseases
-SVM
-Wavelet

10. Filtering
Filter is an electronic device that passes and
blocks certain frequencies. In most system,
noise is suppressed.
The most common types of noises that occur during the
collection of ECG are
Power line Interface Electrode Contact
60 HZ and its noise
multiples less than 0.5Hz

11. Effect of Power line Interface[5]

12. Effect of Electrode contact noise
• Movement of body
and respiration
• Lose of contact

13. Solution
• Bandpass filter : Cascading a high pass and low pass filters the low and
high frequency signal will be canceled.
Input HPF LPF
ECG
• Once the clear ECG signal is obtained, further analysis is applied depending on
the application.

14. EXAMPLE
•To calculate the heart beat, passing the filtered ECG through the differentiator will help
to determine the maximum picks by detecting the slope.
•R-R interval can then be calculated as shown in the diagram
•The given formula will then calculate the Heart Beat.

15. Adaptive Filtering Algorithms
for Noise Cancellation of ECG Signal with reference signal[4]
In this case two signals are required
Primary signal Reference Input
which which is the
has two components common noises
Clean ECG (S) + Noise signal ( n0 ) Estimated Noise signal (Y)
The adaptive filters essentially minimizes the
error between a primary input, which is the
noisy ECG, and a
reference input, which is either noise that is
correlated in some way with the
noise in the primary input or a signal that is
correlated only with ECG in the
primary input.

16. The adaptive noise canceling system of ECG signal
Primary signal
Adaptive
Algorithm

17. Further Analysis
Wavelet transforms are used in detecting
irregularities in QRS section accurately.
Wavelet Energy based Diagnostic Distortion
(WEDD) for distortion measurement.
Heart Rate Variability (HRV) to measure
regulated emotional responding.

18. CONCLUSION
Using the different techniques in processing the ECG,
we hope to see accurate, robust ,and more advanced
tools in cardiac care.
We believe this will lead to put an end to heart disease
which is the number one killer.

19. THANK You
Q /A

20. References
[1] L. Wang, “The ECG Signal Processing by ADSP-21062 Digital Signal Processor”,
Thesis submitted to the College of Engineering and Mineral Resources at West Virginia
University,2005 .
[2] C. Saritha, V. Sukanya & Y. Narasimha Murthy, ECG Signal Analysis Using Wavelet
Transforms, February 2008 .
[3] http://www.adinstruments.com/, “Electrocardiogram and Heart Sounds”, An
Introduction to the recording and analysis of electrocardiograms, and the sounds of
the heart.
[4] Md. Zia Ur Rahman, R.A.Shaik & D V R. K. Reddy, “Noise Cancellation in ECG Signals
using Computationally Simplified Adaptive Filtering Techniques: Application to
Biotelemetry” ,
[5] S. Z. Islam1, S. Z. Islam2, R. Jidin3 & M. A. M. Ali4, “Performance Study of Adaptive
Filtering Algorithms for Noise Cancellation of ECG Signal”,