          kf.H = [ O I O O O ;
                O O Tpr O O ; ];
            kf.R = diag([vor_dme.stdv vor_dme.stdm]).^2;
            kf.z = [ zv' zp' ]';
        else
            kf.H = [ O I O O O ; ];
            kf.R = diag([vor_dme.stdv]).^2;
            kf.z = zv;
        end

        % a posteriori states are forced to be zero (error-state approach)
        kf.xp = zeros(n , 1);
        % Execution of the extended Kalman filter
        kf = kalman(kf, dtg);

        %% OBSERVABILITY

        % Number 