plot white noise PSD in matlab?

[fanshuo]

noise psd

how to do that without using "psd" command?
Thanks!

 

[abaidullah]

psd white noise

calculate the power spectral density using mathematical expressions and then plot the array.

Simple

 

[fanshuo]

power spectral density matlab

there is a scaling factor after the fft to make it a unitary transform
what is that?

 

[atulbhatia]

psd noise

you can see fft of x as
y=fft(x,512);
df=fs/512;
m=fftshift(abs);
m=m.^2;
m1=20*log10(m);
p=unwrap(angle);
f = -(fs/2)+df:dffs/2);
%f=(0:length-1)*fs/length;
figure;
plot(f,m1);title('magnitude')

 

[mskarthik]

Re: psd noise

you can see fft of x as
y=fft(x,512);
df=fs/512;
m=fftshift(abs);
m=m.^2;
m1=20*log10(m);
p=unwrap(angle);
f = -(fs/2)+df:dffs/2);
%f=(0:length-1)*fs/length;
figure;
plot(f,m1);title('magnitude')

f = -(fs/2):dffs/2)-df; would be better