Ecg compression using fft

2,827 views
2,524 views

Published on

ECG COMPRESSION USING
FFT
The electrocardiogram (ECG) is a diagnostic tool that is routinely used to assess the electrical and muscular functions of the heart. Sometimes it is required to send the ECG signals from one place to another place. The ECG signals are compressed at first to reduce the amplitude and frequency and then transferred. ECG signals are compressed by using many techniques. One of the most important technique is FFT.
FFT (Fast Fourier Transform) is a technique used to convert analog signal to digital signal.
In FFT, The total process takes five steps:-
1) Input signal
2) Compression (counter A)
3) Compression (counter B)
4) Recovery of the original signal by using IFFT
5) Error checking
Now the detailed explanation of the above steps is given below
 At first the input signal (ECG signal) is taken.
 There are two stages for compression. In first stage of compression there is a counter A. It identifies the non-zero values of the signal before compression. After compression if the length of the compressed signal is less than the length of the actual signal, then zero padding is done to make equal the lengths of compressed and actual signal.
 Now the signal is passed through the counter B. It identifies the non-zero values after the compression of the signal. Now after compression if the length of the compressed signal is greater than the length of the actual signal, then TRUNCATION of the signal is done.
 Now by applying IFFT (Inverse Fast Fourier Transform) the original ECG signal is recovered.
 The Error is checked at the last stage.


Compression ratio is given by
CR=(B-A)/B *100
CR-Compression ratio
A-compression in counter A
B-compression in counter B

Compression ratio is a major factor to determine how much compression the signal undergoes.
 The compressed signal contains only positive values.
Thus ECG signal is compressed by using FFT technique.

Applications:-
• It finds application in hospitals, when a patient’s report is to be send to another doctor in prenomial place.


Published in: Education, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
2,827
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
73
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Ecg compression using fft

  1. 1. ECGCOMPRESSION USING FFT
  2. 2. ECGThe ECG (electrocardiogram)is a diagnostic tool that is routinely used to assess the electrical and muscular functions of the heart.Sometimes it is required to send the ECG signals from one place to another place. The ECG signals are compressed at first to reduce the amplitude and frequency and then transferred.
  3. 3. FFT• ECG signals are compressed by using many techniques. One of the most important technique is FFT.• FFT (Fast Fourier Transform) is a technique used to convert analog signal to digital signal.
  4. 4. FFT
  5. 5. Five Stages In FFT, The total process takes five steps:-1) Input signal2) Compression (counter A)3) Compression (counter B)4) Recovery of the original signal by using IFFT5) Error checking
  6. 6. First stageThe input signal (ECG SIGNAL) IS TAKEN
  7. 7. Compression stage (counter A) There are two stages for compression. In first stage of compression there is a counter A. It identifies the non-zero values of the signal before compression. After compression length of the compressed signal is compared with the length of the actual signal.
  8. 8. ZERO PADDING• If the length of the compressed signal is less than the length of the actual signal, then zero padding is done to make equal the lengths of compressed and actual signal.
  9. 9. ZERO PADDING
  10. 10. COMPRESSION STAGE (COUNTER B)• Now the signal is passed through the counter B. It identifies the non-zero values after the compression of the signal.• After compression length of the compressed signal is compared with the length of the actual signal
  11. 11. TRUNCATION Now after compression if thelength of the compressed signal is greaterthan the length of the actual signal, thenTRUNCATION of the signal is done.
  12. 12. TRUNCATION
  13. 13. COMPRESSED ECG SIGNAL
  14. 14. Recovery of the original signal by using IFFT Now by applying IFFT (Inverse Fast Fourier Transform) the original ECG signal is recovered.
  15. 15. Recovery of the original signal by using IFFT
  16. 16. ERROR CHECKING STAGEThe recovered signal y’(t) is compared with the original signal y(t).Error is given by e(t)=y(t)-y’(t) e(t)=error in the recovered signal y(t)= original signal y’(t)=recovered signal
  17. 17. ERROR CHECKING STAGE
  18. 18. The compressed signal contains only positive values
  19. 19. Compression Ratio• Compression ratio is given by• CR=((B-A)/B) *100• CR-Compression ratio• A-compression in counter A• B-compression in counter B• Compression ratio is a major factor to determine how much compression the signal undergoes.
  20. 20. Applications It finds application inhospitals, when a patient’s report is to besend to another doctor in prenominal place.

×