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
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