Colored Noise Generation in Matlab

Question

i would like to ask help about how to generate different noises in signal processing,according to this definition

http://en.wikipedia.org/wiki/Colors_of_noise

where for white noise alpha=0;,and for different noises we have different values of alpha,i prefer to have code in matlab,so please help me to write this code

Answer 1

You can use this code. It is very straigthforward:

function [W,t]= colornoise(a,b,T,N)
 randn('state',100);      %fixing the state of generator
 dt=T/N;
 dW=sqrt(dt)*randn(1,N);

 R=4;                      %fixed for this computation
 L=N/R;
 Xem=zeros(1,L);
 Xzero=0;
 Xtemp=Xzero;
 Dt=R*dt;

 for j=1:L
    Winc=sum(dW(R*(j-1)+1:R*j));
    Xtemp=Xtemp+a*Dt*Xtemp+b*Winc;
    Xem(j)=Xtemp;
 end

 W=[Xzero,Xem];
 t=[0:Dt:T]

where a,b (intensity of white noise) and T (the upper limit to time vector), N (the no. of samples which essentially defines the step size

Answer 2

Generate a pink noise signal 2048 samples in length.

hcn = dsp.ColoredNoise('InverseFrequencyPower',1,'SamplesPerFrame',2048);
x = step(hcn);
plot(x);