function [B,A] = biquad_hpf(fc, q, fs) %BIQUAD_HPF biquad high-pass filter % [B,A] = biquad_hpf(fc, q, fs) % % Input: % fc - cutoff frequency (Hz) % q - Q-factor % fs - sampling frequency (Hz) % % 2009-11-30 by MARUI Atsushi % based on "Cookbook formulae for audio EQ biquad filter % coefficients" by Robert Bristow-Johnson. % 2010-01-18 updated to conform better to Bristow-Johnson's definition omega = 2 * pi * fc / fs; alpha = sin(omega)/(2*q); B = [ (1 + cos(omega)) / 2 -(1 + cos(omega)) (1 + cos(omega)) / 2 ]; A = [ 1 + alpha -2 * cos(omega) 1 - alpha ];