what is the noise bandwidth considered while calcuating SNR ; for func of the form .. r = snr(x,fs,n)

what is the noise bandwidth considered while calcuating SNR ; for func of the form .. r = snr(x,fs,n)

Answer 1

[Devineni Aslesha]

The noise bandwidth is equal to the sampling frequency. This can be obtained by plotting the power spectral density of noise.

Use the below code for reference.

rng default 
Fi = 2500; 
Fs = 48e3; 
N = 1024; 
x = sin(2*pi*Fi/Fs*(1:N)) + 0.00001*randn(1,N); 
w = kaiser(numel(x),38); 
[Sxx, F] = periodogram(x,w,numel(x),Fs,'centered'); 
plot(F,10*log10(Sxx));
xlabel('Frequency (Hz)'); 
ylabel('Power/Frequency(dB/Hz)'); 
title('Power Spectral Density'); 

In the above plot, noise bandwidth = Fs

Doc Link:

https://www.mathworks.com/help/signal/ref/snr.html

https://www.mathworks.com/help/signal/ref/periodogram.html

[Veeresh S]

Thanks for the reply Devineni Aslesha.

If i get the SNR for the same i'll see the following

which shows the freq componets upto fs/2 .

So , which is it fs or fs/2 ?

[Devineni Aslesha]

In the given plot, noise bandwidth is equal to fs. Eventhough, the frequency components are shown upto fs or fs/2, the only difference it makes is a single sided or double sided spectrum respectively. In both cases, noise bandwidth is equal to fs.