# Time freq : morlet wavelet convolution computation

Dear Brainstorm Users,

I am currently trying to better understand time-frequency analysis. There is a point that I don't understand in the method of calculation of the wavelet coefficients in the function morlet_transform.m.

At the line 101 of the matlab code: `P(ch,s,: ) = conv2(x(ch,:), W{s}, 'same') * Ts;`
We can see the computation of the convolution between the signal x and the wavelet W at the specified scales s. But I don't understand why the convolution is multiplied by the sampling period Ts. If i'm not mistaken the wavelet is already created at the same sampling frequency of the signal, so I guess I'm missing something here.

I'm really sorry if the answer is evident but I can not find in the Mike x Cohen's book anything about multiplying the convolution by the sampling rate. I'm relying on his courses to better understand all these analyses, so maybe I am just blind and don't see it. Could you provide me any reference or explanation about this multiplication between conv2 and Ts in the brainstorm code ?