function [X,freq]=positiveFFT(x,Fs) 
N=length(x); 
k=0:N-1; 
T=N/Fs; 
freq=k/T; %create the frequency range 
X=fft(x)/N; % normalize the data
cutOff = ceil(N/2); 
X = X(1:cutOff); 
freq = freq(1:cutOff);