How to add 'AWGN' noise to a filtered data stream?

I want to add Additive White Gaussian Noise (AWGN) to a filtered data stream. not sure how to include this in the code.

Answer 1

[Wayne King]

Use randn(). Add a vector the same size to your filtered data.

Multiply the randn() vector by the standard deviation to give it a specified variance.

Ex:

     %sqrt(2) is the standard deviation. Variance is 2
      x  = sqrt(2)*randn(1000,1);

Creates a WGN vector where the random variables follow a N(0,2) distribution.