How to add AWGN noise using randn function?

I have a discrete time signal which I generated as follows:

I wish to add AWGN noise using randn() function with mean=0 and variance=0, 0.1, 0.5, 1, 1.5 and 3.

The code i have written is:

How can I modify my function to add the noise and later on, demodulate it back into a matrix (as shown in 'w' array)?

Answer 1

[Aastha]

Hi @Afaq Ahmad,

To add AWGN noise using the "randn" function in MATLAB, you can follow the steps outlined below:

1. The "randn" function in MATLAB generates samples from a standard normal distribution, which has a mean of 0 and a variance of 1.

You may refer to MathWorks documentation of "randn" function for any queries on it:

https://www.mathworks.com/help/matlab/ref/double.randn.html

2. To add AWGN noise with a specified variance "v", you can scale the output of "randn" using the square root of the variance. You may refer to the MATLAB code snippet below to do so:

awgn_noise = sqrt(v).*randn(); % N(0,v) 

I hope this helps!