need to convert excel (time domain data ) to frequency domain data

i have excel (.csv) file ... that is time vs acceleration data for cantilever beam. i need to convert in to frequency domain for find out natural frequency of cantilever beam

Answer 1

[rifat]

Assuming the Excel file contains time data in column 1 and acceleration data in column 2

% read data
data=xlsread('fileName.xlsx');

% frequency analysis
y=fft(data(:,2));
len=length(data(:,1));
n=0:len-1;
fs=50; % mention your sampling freq
N=n*fs/(len-1);

plot(N,abs(y));