Discussion in 'Electrical | Electronics | Communications' started by Vila, Aug 31, 2008.

1. ### Vila Apprentice

Hiii everybody,

What is the difference between White Noise and White Gaussian Noise? And what is Additive White Gaussian Noise? I have refer to wikipedia, google and yahoo, but can't really differentiate them. Can someone please explain to me in detail??

Thank you.

#1
2. ### ash Moderator

Engineering Discipline:
Communications
Ah, the difference between White Noise and White Gaussian Noise is that the latter has a "Gaussian" or normal amplitude distribution (bell shaped like in statistics), but both still has constant power spectral density. In AWGN, the word "additive" simply shows that the noise has an additive effect on a signal, rather than a convoluted effect in communication systems.

#2
3. ### Vila Apprentice

Hiiiiii,

Hi Ash, thanks a lot for your reply and explaination. Now i understand better, but could you explain more on AWGN? What you mean by the additive effect on the signal and convoluted effects on communication system?

Thanks dude

#3
4. ### ash Moderator

Engineering Discipline:
Communications

For example, we know that in communication transmission, the data signal x(t) is "combined" with other signal h(t) to produce a third signal (normally by integral transform- ie convolution). Because the final signal is sent through a wireless channel consisting of interference, noise signal n(t) is combined together. However, n(t) does not have an integral effect on the signal.. it is merely added to it, thus only the amplitude of the signal changes. The final equation of the signal is something like this:

y(t) = x(t)*h(t) + n(t).

AWGN models the noise in the communication channel, so it is used in simulation and calculations. It is not the only model, but its the most frequently used. MATLAB has an AWGN function in which the second parameter is the noise level in dB.

Hope that helps!