Communications Toolbox

awgn

Add white Gaussian noise to a signal

Syntax

• y = awgn(x,snr);
  y = awgn(x,snr,sigpower);
  y = awgn(x,snr,'measured');
  y = awgn(x,snr,sigpower,state);
  y = awgn(x,snr,'measured',state);
  y = awgn(...,powertype);
  

Description

y = awgn(x,snr) adds white Gaussian noise to the vector signal x. The scalar snr specifies the signal-to-noise ratio in decibels. If x is complex, then awgn adds complex noise. This syntax assumes that the power of x is 0 dBW.

y = awgn(x,snr,sigpower) is the same as the syntax above, except that sigpower is the power of x in dBW.

y = awgn(x,snr,'measured') is the same as y = awgn(x,snr), except that awgn measures the power of x before adding noise.

y = awgn(x,snr,sigpower,state) is the same as y = awgn(x,snr,sigpower), except that awgn first resets the state of the normal random number generator randn to the integer state.

y = awgn(x,snr,'measured',state) is the same as y = awgn(x,snr,'measured'), except that awgn first resets the state of normal random number generator randn to the integer state.

y = awgn(...,powertype) is the same as the previous syntaxes, except that the string powertype specifies the units of snr and sigpower. Choices for powertype are 'db' and 'linear'. If powertype is 'db', then snr is measured in dB and sigpower is measured in dBW. If powertype is 'linear', then snr is measured as a ratio and sigpower is measured in watts.

Examples

The commands below add white Gaussian noise to a sawtooth signal. It then plots the original and noisy signals.

• t = 0:.1:10;
  x = sawtooth(t); % Create sawtooth signal.
  y = awgn(x,10,'measured'); % Add white Gaussian noise.
  plot(t,x,t,y) % Plot both signals.
  
  
  

See Also

wgn, randn

arithenco

bchdeco