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- 25th March 2006, 06:21 #1

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## noise addition in matlab

How can I accurately add to my signal white

gaussian noise of exact SNR in dB (in POWER not

voltage terms)?

when I use awgn(...) function it seems

to me the noise has more power than I

set in its SNR parameter.

- 25th March 2006, 06:21

- 25th March 2006, 06:41 #2

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## noise addition in matlab

Hi,

I suggest you use randn().

1D noise:

Code:noise = sqrt(variance)*randn(1, symbols_per_frame );

Code:noise = sqrt(variance)*( randn(1,symbols_per_frame) + j*randn(1,symbols_per_frame) );

Davy

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- 25th March 2006, 06:41

- 25th March 2006, 09:26 #3

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## noise addition matlab

please tell me how then set SNR in power terms?

- 25th March 2006, 09:26

- 25th March 2006, 11:17 #4

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## Matlab question (noise addition)

Sorry, I am not familiar with awgn().

You may turn to NewsGroup: comp.soft-sys.matlab

to ask the question.

You can access NewsGroup via groups.google.com

Regards,

Davy

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- 26th March 2006, 16:52 #5

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## Matlab question (noise addition)

Hi lincolndsp,

from the formula SNR = 10 * log_10 (P_signal/P_noise) we get (Ps/Pn) = 10^(SNR/10).

In my simulation I usually set the power of the input signal Ps equals to 1, then vary the power of the noise (variance). So,

Pn = 10^(-SNR/10);

noise = sqrt(Pn)*randn(1, symbols_per_frame );

best

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