finding the first, second and third maxima in the signal

Can someone please help me with the code for finding the signal peaks in the below figure .

I hae tried using for loops, and also MATLAB function findpeaks() . I am new to MATLAB and I am not sure if I am doing this correctly. Please help me.

http://tinypic.com/r/59u06q/5

[Azzi Abdelmalek]

In your image, some peaks are ignored

[Ricky]

Yes for further processing of the Data I need only the peaks that I have marked in circle.

[Iain]

What is it about the peaks that tell you to NOT ignore them?

[Azzi Abdelmalek]

And how can we do it by code? You should explain why some peaks are ignored, If there is no explanation it's impossible to do it by program.

[Ricky]

These are like echos of a signal and I want only the first signal and the next 3 echos of the signal.

Answer 1

[Azzi Abdelmalek]

I suggest that you do it manually using the function ginput

[Ricky]

Hello Azzi, I do not want to do this manually. Somehow I need to write a code which says that if my peak value is greater than previous 3 values and next 3 values it is a good Data point. Also as soon as i get 4 values in this variable I should stop the execution.

[Azzi Abdelmalek]

[peaks,index]=findpeaks(y)
for k=1:numel(peaks)
  ii=index(k);
  jj=0;
  if abs(y(ii)/y(ii-1))>=3 & abs(y(ii)/y(ii+1))>=3
      jj=jj+1
      real_peak(jj)=peaks(k)
      index_peak(jj)=ii
  end
end