Hi Alberto,
You can include information regarding ‘K’ while defining the numerator and denominator coefficients in the ‘freqz’ command. In this case, the numerator coefficients would look like this: B = [1/3...0….0.. 1/3 (at index K+1) ..0…0…1/3(at index 2K+1)]. For example, for K = 3,
B = [1/3 0 0 1/3 0 0 1/3];
The code snippet below delays a sine wave of frequency 100Hz sampled at 6KHz by 10 samples. 10 samples in this case corresponds to a delay of pi/3.
Fs = 6000;
f = 100;
t = 1/Fs:1/Fs:.1;
x = sin(2*pi*f*t);
plot(x);
M = Fs/f;
K = (M/6);
B = zeros(1,2*K);
A = 1;
indices = [1,K+1,2*K+1];
B(indices) = 1/3;
y = filter(B,A,x);
hold on, plot(y)
hold off
figure, freqz(B,A)
However, the above code requires K to be a multiple of 6. If the K value you are using is not a multiple of 6, you could define K as below:
K = round(M/6);
Hope it helps!
