computing SNR in matlab

Hello all,

I have a noisy sinisoid signal and would like to compute its SNR in MATLAB. Can anybody help me? Thanks.

Answer 1

[Rick Rosson]

1. What is the amplitude of the sine wave?
2. Is the noise additive white Gaussian or some other type? If Gaussian, what is the mean and standard deviation?

[Bahareh]

Here is my code. I actually want to find the SNR of my output filter 'yf'. I was wondering if you could please help me.

{

dt = 1/5e4;fs=1/dt;

t1=cos(2*pi*1e3*(0:dt:6e-3));

t2=cos(2*pi*2e3*(0:dt:6e-3));

t3=cos(2*pi*3.5e3*(0:dt:6e-3));

t4=3*cos(2*pi*20e3*(linspace(2e-3,2.1e-3,length(t3))));

x=t1+t2+t3+t4;

y=awgn(x,10,'measured');

wpass=2*1e4/fs; wstop=2*2e4/fs; %normalized passband & stopband frequencies

[N,wn]=buttord(wpass,wstop,1,50); %Rpass=1dB & Rstop=50dB

[B A]=butter(N,wn); % use butter to obtain an IIR filter of Butterworth type

yf=filtfilt(B,A,y);}