How to set threshold point to the first peak arrival?

1.how to set first peak arrival

2.how to set threshold point to the first peak arrival to get "x y x" output coordinate needed for neural network input.

Answer 1

[Mathieu NOE]

hello

I wonder why doing the complex fft / ifft to remove low frequency signal

this can be done easily still in time domain using filtfilt (with no phase distorsion)

now I am not sure which specific point is to be found in this signal

my understanding was to find the max peak amplitude point , but I am not sure what the breakout point is for

my (simpler) code :

[A]=xlsread('A.xlsx');
% save A;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
x = A(:,1);
y = A(:,2);

dt = mean(diff(x));
Fs = 1/dt;

% some additionnal high pass filtering
N = 2;
fc = 1.2e8;
[B,A] = butter(N,2*fc/Fs,'high');
yy = filtfilt(B,A,y);

% first peak arrival point = max of abs(yy)
[val,ind] = max(abs(yy)); % 
tx = x(ind);

figure(1),plot(x,y,'b',x,yy,'r',tx,val,'+g','linewidth',2,'markersize',12);grid on

[Wan Daniel]

the breakpoint is use to detrend the signal since the original signal is "shfited" upward from the breakpoint line

[Mathieu NOE]

hello

using the high pass filter as shown in my code above will remove also that shift

back to the original question : is the green cross the point you're looking for or what is your definition of "first peak arrival" ?