I'm wondering if I have calculated a nulling filter coefficients correctly:
$\ 1, -2\cos(0.44\pi), 1$
I have to make a nulling filter that filters out the frequencies $\theta = 0.44\pi$. I've been told that the formula for nulling filters is $y[n] = x[n] - 2\cos(\theta)*x[n-1]+x[n-2]$.
If I'm correct the two 1s come from the fact that $\ x[n]$ and $\ x[n-2]$ both have a coefficient of 1 and no other variable and the $\ -2\cos(0.44\pi)$ comes from the $\ - 2\cos(\theta)*x[n-1]$ and the fact that $\theta$ = 0.44$\pi$.
If the coefficients are correct, is all I have to do to find the output signal just multiply the input signal by each coefficient and add them together (convolution sum)?