# randn, awgn, wgn

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PChoppala on 1 Dec 2011
Hi I have a small doubt. Is
a = awgn(randn(20,20), 6.7) and
a = wgn(20,20,6.7) the same
Aim is, I want a 20X20 frame with a SNR = 6.7 dB

Wayne King on 1 Dec 2011
Hi, SNR implies that you have a signal, in your call to awgn() you have no signal, just noise.
If you use awgn() you should input your signal and awgn() will add noise at the specified SNR.

PChoppala on 1 Dec 2011
Hi there, thank you, but my signal now is an 20X20 frame that I write as randn(20,20). How about that?
Which is right?
If nothing, can you help me out to create a 20X20 frame?
Wayne King on 1 Dec 2011
but don't want your "frame" to be a matrix of constants then? Again, SNR implies that you have a signal. Do you really want to call randn(20,20) a signal. If you just want noise of a specified variance, that is different than SNR
PChoppala on 1 Dec 2011
Well, I am typing the statement as it is given in the book. Please help me out.
1. A frame of data has been generated with n=20, m=20 and std = 3
Can you help me create a frame with only this data?
2. The initial SNR of the frame is 6.7
Add this data as well and help me create the frame
Cheers a lot.