how to plot pressure spectrum for a point in turbulent flow

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I have pressure data for a point in turbulent flow,the data are not sampled at constant time step
The data are sampled from time=0.0616086-0.0928762 second, the time step is not constant cahnging between 6*10^-7 tp 9*10^-7 seconds
the pressure data are shown below
I was trying to use pwelch function to get the pressure spectra but i should have constant sampling frequency so i make interpolation for the data to have constant time step of 1*10^-7
then i tried to apply pwelch function
%____interpolatd data_____________________
tq=t(x1):1*10^-7:t(x2);
p0q=interp1(t1,p01,tq,'linear');
%_____________pwelch func________________
fs=1*10^7;
[pxx0,f] = pwelch(p0-mean(p0),[],[],[],fs);
pxx0=10*log10(pxx0);
figure(1)
semilogx(f,pxx0)
this is the data in frequency domain, the figure does not seems resonable
does anyone have tried to use pwelch for pressure spectra to help me in fuction implementation?

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