calc_transfer.m

Contents

• Vector Initialization
• Transfer Function Calculations
• Returned Values

This function calculates the transfer function of the combined equalizer. the function returns a vector containing the phase of the equalizer, and another vector containing the magnitude of the equalizer. w0_vector provides a vector to plot the phase or magnitude against. The frequencies in this vector are logarithmically spaced.

function [filter_mag,filter_phase,w0_vector] = calc_transfer(w0,q0,hbp,n)

Vector Initialization

The w0_vector (the x axis in a bode plot) is created based on the maximum and minimum center frequencies of the equalizer. Also, the vector which will hold the complex transfer function of the equalizer is intialized

        w0_vector = logspace(log10(w0(1)*.01),log10(w0(n)*100),1000);
        filter_vector = zeros(1,1000);

Transfer Function Calculations

For each filter in the equalizer, the parameters of the filter are extracted from the input, and the second order transfer function is calculated. These individual transfer functions are added, since each filter would be connected in parallel.

        for filter_n = 1:n


            %calculate the filter parameters...
            w0f = w0(filter_n);
            hbpf = hbp(filter_n);
            q0f = q0(filter_n);

            %calculate the filter function...
            current_filter_func = (-hbpf * (w0f/q0f)*j.*w0_vector)./((j.*w0_vector).^2 + ((w0f/q0f)*j.*w0_vector) + (w0f^2));

            %adding the filters in parallel...
            filter_vector = filter_vector + current_filter_func;
        end

Returned Values

the magnitude and phase of the combined equalizer are returned. the x axis vector has already been created.

        %returns
        filter_mag = abs(filter_vector);
        filter_phase = angle(filter_vector);

end

Published with MATLAB® 7.4