white noise has flat power spectral density.

Question

I am trying to prove that the white noise has constant power spectral density using matlab but the amplitude of the spectrum looks like random amplitude.

can anyone tell me why?

here is my code.

noise = randn(1,10000);
fft_noise=fft(noise);
plot(abs(fft_noise(1:5000)))

thanks.

Answer 1

Your method is incorrect. See this web site for how to compute the power spectral density.