how to find time corresponds to peak of plot?

Hello to everyone.

I have a signal which it is photoelectron vs. Time, I want to interpolate it with factor of 4, so I did it and derived photoelectron vs. sample. Then, I want to limit this signal just 240 sample to the right and 240 sample to the left. Now I want to know at which time I have peak? Can anyone help me? What should I do with time vector to achieve this?

Here is my codes and data of signal and time are also attached:

%% interpolation
N_interpolation=4; 
signal_padd_zero=zeros(1,N_interpolation*length(lowpass_signal));
signal_padd_zero([1:N_interpolation:end])=lowpass_signal;
interpolated_signal=lowpass(signal_padd_zero,0.01);
plot(interpolated_signal, 'b.-')
axis tight
xlabel('samples')
ylabel('photoelectron')
title('interpolated signal')

%% Limited signal
% max sample
[~,index_of_interpolated_signal]=max(interpolated_signal);
sprintf('Maximum of N occurred at index position %d.',...
    index_of_interpolated_signal)
% range of samples for processing 
% we limit the signal in order to reduce the computation time
x1=index_of_interpolated_signal-(60*N_interpolation);
x2=index_of_interpolated_signal+(60*N_interpolation);
interpolated_signal=interpolated_signal(x1:x2);
figure;plot(interpolated_signal, 'b.-')
axis tight
xlabel('samples')
ylabel('photoelectron')
title('limited  signal')

%% now how can I find the time that corresponds to the peak?

[majid]

because I interpolate then limit the signal and also I plot the signal photoelectron vs. sample , I dont hve any idea abot time!

Answer 1

[KSSV]

If (t,x) is your time and respective data.

[val,idx] = max(x) ;
t_maxx = t(idx)

[KSSV]

Op Commented:

sorry, but my plot isnt (t,x) and also if you look at my x axis it is sample and not time. furthermore, x axis after interpolation was changed, but time vector is still fixed.

I asked about time? what should I do to find at which time I have peak?

[KSSV]

load('time.mat')
load('signal.mat') 
[val,idx] = max(lowpass_signal) ;
t_maxx = t(idx) ; 

plot(t,lowpass_signal)
hold on
plot(t_maxx,val,'*r')

[majid]

I want to find peak at the interpolated_signal plot, not lowpassed signal!

this-> interpolated_signal=interpolated_signal(x1:x2);