I have a Biquad II filter implementation in my embedded environment and I'm trying to find some equations to generate the coefficients for it.
I have already found the Audio Eq Cookbook, which simply describes how to calculate all of the coefficients for Type I.
LPF: (Taken from Audio Eq Cookbook, Type I Equations)
omega = 2*PI*frequency/sampleRate sin = sin(omega) cos = cos(omega) alpha = sin/(2*Q) (if Q is specified) = sin*sinh[ ln(2)/2 * bandwidth * omega/sin ] (if bandwidth is specified) b0 = (1 - cos)/2 b1 = 1 - cos b2 = (1 - cos)/2 a0 = 1 + alpha a1 = -2*cos a2 = 1 - alpha
What are the equations for type II coefficients?