Matlab noise in frequency response function (FRF)

Question

I am calculating the natural frequencies and the corresponding FRF of a test sample that is excited with a hammer with an accelerometer attached to the tip as input signal and another accelerometer attached to the test sample to measure the response. The calculation of the natural frequencies works fine, however, when I am plotting the normalized FRF of 40 independent measurements, the noise makes it impossible to discern the natural frequencies as you can see below.

Then I found out about the hanning window and I applied this to my data, which gave me the following FRF:

This is an upgrade, but still way too much noise :-(

I am hoping someone can help me what to do next to remove as much noise as possible! Any help would be appreciated!

Answer 1

I am not sure this is a StackOverflow question, but I will still try to help you:

I would try to use autocorrelation or fft . This question could also help you: Determine frequency from signal data in MATLAB