Filter amplitude vs time data

Dear,

Along with saying hello, I wanted to ask for your help please. I need to identify the wave with the greatest amplitude (maximum peak), and intersect it with a threshold value, in this case of 1.5, and identify the points of intersection, that is, the nodes where the curve of the maximum peak intersects with the threshold value, to to be able to identify node 1 and node 2 with respect to the horizontal axis (time series), for which I attach the data, and an image of the problem. Best regards.

close all, clear all, clc

data=load('D:\HP CIVIL\serie de tiempo\data.txt');
t=0:10:4*3600;

plot(t,data)
xlabel('Time (s)'); ylabel('Amplitude (m)')
hold on
plot(t,1.5,'r')

Answer 1

[KSSV]

data=load('data.txt');
t=(0:10:4*3600)';

[val,idx] = max(data) ; 

ti = (0:0.05:4*3600)' ;
datai = interp1(t,data,ti) ; 

id1 = abs(datai-1.5)<=0.001 ; 
ti_th = ti(id1) ; 
datai_th = datai(id1) ; 

id2 = knnsearch([ti_th datai_th],[t(idx) data(idx)],'k',2) ; 


plot(t,data)
xlabel('Time (s)'); ylabel('Amplitude (m)')
hold on
plot(ti_th,datai_th,'.r')
plot(ti_th(id2),datai_th(id2),'Ok')

[ignacio bobadilla tapia]

@KSSV

Estimated,

Along with saying hello, what I need specifically is to calculate the time differential of the intersection of the threshold (1.5) with the curve of maximum amplitude, for which I attach an explanatory image.

Thanks greetings.

[ignacio bobadilla tapia]

Estimated, don't you have some simpler code? Regards.