Noise Normalisation
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From: volkanizma2003 on 29 Jun 2010 15:31 Hi, I have some problems regarding noise normalisation. I have original signal and I want to add a noise. EbN0db= 0.00; SNRv=10^(EbN0db/10); global sigma; sigma=1/sqrt(SNRv); b=randn(1,1200); gaus=sigma*b; x= round(randn(1,1200)); % my original signal y= gaus % my noise z= x+ gauss % original signal + noise Question 1.) Do I need to normalize the noise for example multiple by 0.1 z=x+ 0.1*gauss %will it be like this? is this noise`s phase is equal to my original signal or less than my original signal? Thanks for your time.
From: John on 30 Jun 2010 06:40 On Jun 29, 3:31 pm, "volkanizma2003" <ozduranvolkan(a)n_o_s_p_a_m.gmail.com> wrote: > Hi, I have some problems regarding noise normalisation. I have original > signal and I want to add a noise. > > EbN0db= 0.00; > SNRv=10^(EbN0db/10); > global sigma; > sigma=1/sqrt(SNRv); > > b=randn(1,1200); > gaus=sigma*b; > > x= round(randn(1,1200)); % my original signal > y= gaus % my noise > z= x+ gauss % original signal + noise > > Question 1.) Do I need to normalize the noise for example multiple by 0.1 > > z=x+ 0.1*gauss %will it be like this? > > is this noise`s phase is equal to my original signal or less than my > original signal? > > Thanks for your time. 1) You already scaled the noise when you multiplied it by 1/sqrt(SNR) 2) Adding the noise does not change the phase, only the amplitude John
From: Greg Heath on 30 Jun 2010 09:08 On Jun 29, 3:31 pm, "volkanizma2003" <ozduranvolkan(a)n_o_s_p_a_m.gmail.com> wrote: > Hi, I have some problems regarding noise normalisation. I have original > signal and I want to add a noise. > > EbN0db= 0.00; > SNRv=10^(EbN0db/10); > global sigma; > sigma=1/sqrt(SNRv); > > b=randn(1,1200); > gaus=sigma*b; > > x= round(randn(1,1200)); % my original signal > y= gaus % my noise > z= x+ gauss % original signal + noise > > Question 1.) Do I need to normalize the noise for example multiple by 0.1 > > z=x+ 0.1*gauss %will it be like this? > > is this noise`s phase is equal to my original signal or less than my > original signal? > > Thanks for your time. If x is complex why aren't you adding complex noise? Greg
From: third_person on 30 Jun 2010 11:33 Can you tell me why you are normalizing it by sqrt(SNR)? I generate AWGN as Noise = (randn(1,10)+j*randn(1,10))/sqrt(2)*10^(-SNR/20) % quadrature noise Am I missing something? > Hi, I have some problems regarding noise normalisation. I have original >signal and I want to add a noise. > >EbN0db= 0.00; >SNRv=10^(EbN0db/10); >global sigma; >sigma=1/sqrt(SNRv); > >b=randn(1,1200); >gaus=sigma*b; > >x= round(randn(1,1200)); % my original signal >y= gaus % my noise >z= x+ gauss % original signal + noise > >Question 1.) Do I need to normalize the noise for example multiple by 0.1 > >z=x+ 0.1*gauss %will it be like this? > >is this noise`s phase is equal to my original signal or less than my >original signal? > >Thanks for your time. >
From: Greg Heath on 30 Jun 2010 12:01
On Jun 30, 11:33 am, "third_person" <third_person(a)n_o_s_p_a_m.ymail.com> wrote: > Can you tell me why you are normalizing it by sqrt(SNR)? > > I generate AWGN as > > Noise = (randn(1,10)+j*randn(1,10))/sqrt(2)*10^(-SNR/20) % quadrature > noise > > Am I missing something? > > > > > Hi, I have some problems regarding noise normalisation. I have original > >signal and I want to add a noise. > > >EbN0db= 0.00; > >SNRv=10^(EbN0db/10); > >global sigma; > >sigma=1/sqrt(SNRv); > > >b=randn(1,1200); > >gaus=sigma*b; > > >x= round(randn(1,1200)); % my original signal > >y= gaus % my noise > >z= x+ gauss % original signal + noise > > >Question 1.) Do I need to normalize the noise for example multiple by 0.1 > > >z=x+ 0.1*gauss %will it be like this? > > >is this noise`s phase is equal to my original signal or less than my > >original signal? > > >Thanks for your time.- Hide quoted text - > > - Show quoted text - There is SNR = (average signal power)/(average noise power) and SNRdB = 10*log10(SNR). Hope this helps. Greg |