close all
clear all


U = 15.0;

f = .01:.005:.3;
w = 2*pi*f;

a = .0081;
b = 0.74;
g = 9.81;

S = a*g^2*exp(-b*((g/U)./w).^4)./(w.^5);

t = 0:.1:600;

H = zeros(1,length(t));


for i = 1:length(w)
H = H + sqrt(S(i))*cos(w(i).*t+2*pi*rand);
end
    
    
figure
plot(t,H);
 