Find the frequency at maximum value in pwelch function

I plotted my pwelch, and I want the frequency at which the graph shows the highest value. In this particular case its around .25. I tried using findpeaks but it gives me some weird answer.

[dpb]

"... findpeaks but it gives me some weird answer"

Show your work; findpeaks should have no problem with that input signal with suitable inputs...

Answer 1

[Aquatris]

You can obtain the frequency and power vectors from pwelch function. Example;

fs = 1e3;
t = 0:1/fs:1-1/fs;
x = sin(2*pi*100*t);
[pxx,f] = pwelch(x,500,300,500,fs); 
plot(f,20*log10(pxx))

then, you can simple do the following to find the frequency corresponding to max peak;

index = find(pxx == max(pxx));
freq_max = f(index); % frequency at which pxx is maximum