Hi everybody
I m generating pink noise (1/f noise) using following procedure.
1. Generate uniformly distributed white noise.
2. Calculate the fastFourier transform (FFT),
3. Impose 1=f distribution on the power spectrum
4. Calculate inverse FFT.
I have used following code for generating pink noise
rand('seed',1);
x=rand(30000,1);
yt(x);
y=(abs(y).^2);
f=(1:30000);
f=f';
y1=(f.^(-0.5)).*y;
pink_noise = real(ifft(y1));
But results are not correct. Can anybody help for solving the problem.
with regards
Wajid
pink noise
Started by ●September 27, 2005
Reply by ●September 27, 20052005-09-27
Hi Wajid,
The only thing that you should do extra is to add
phase information (as randomly "uniform" varying
between -pi and pi) and after multiplying with
magnitude y (magnitude should be normally distributed) y * exp(-(fi))
and then taking the inverse fft will be enough for you
to obtain 1/f noise.
Cheers,
Tolga Esat Ozkurt --- wajid lone <kh_wajid@kh_w...> wrote:
> Hi everybody
>
> I m generating pink noise (1/f noise) using
> following procedure. >
> 1. Generate uniformly distributed white noise.
>
> 2. Calculate the fastFourier transform (FFT),
>
> 3. Impose 1=f distribution on the power spectrum
>
> 4. Calculate inverse FFT. >
> I have used following code for generating pink noise >
>
> rand('seed',1);
> x=rand(30000,1);
> yt(x);
> y=(abs(y).^2);
> f=(1:30000);
> f=f';
> y1=(f.^(-0.5)).*y;
>
> pink_noise = real(ifft(y1)); >
> But results are not correct. Can anybody help for
> solving the problem. >
> with regards >
> Wajid
__________________________________
The only thing that you should do extra is to add
phase information (as randomly "uniform" varying
between -pi and pi) and after multiplying with
magnitude y (magnitude should be normally distributed) y * exp(-(fi))
and then taking the inverse fft will be enough for you
to obtain 1/f noise.
Cheers,
Tolga Esat Ozkurt --- wajid lone <kh_wajid@kh_w...> wrote:
> Hi everybody
>
> I m generating pink noise (1/f noise) using
> following procedure. >
> 1. Generate uniformly distributed white noise.
>
> 2. Calculate the fastFourier transform (FFT),
>
> 3. Impose 1=f distribution on the power spectrum
>
> 4. Calculate inverse FFT. >
> I have used following code for generating pink noise >
>
> rand('seed',1);
> x=rand(30000,1);
> yt(x);
> y=(abs(y).^2);
> f=(1:30000);
> f=f';
> y1=(f.^(-0.5)).*y;
>
> pink_noise = real(ifft(y1)); >
> But results are not correct. Can anybody help for
> solving the problem. >
> with regards >
> Wajid
__________________________________
