www.gusucode.com > 利用MATLAB GUI设计滤波器界面,可以设计IIR滤波器 > AFD/SpecifyFilter_HelpContext.m
function SpecifyFilter_HelpContext % SpecifyFilter_HelpContext is a subfile of the AnalogFilter GUI collection % % James C. Squire, 2002 % Assistant Professor, Virginia Military Institute % ver 1.0 % SpecifyFilter_HelpContext provides simple help information % create help text text{1} = 'Overview: Define a filter, then use the menu to analyze or build it.'; text{2} = ' '; text{3} = 'Filter Purpose'; text{4} = 'Although only low or highpass filters may be designed, they may be concatenated to build bandpass and bandstop filters.'; text{5} = ' '; text{6} = 'Filter Type'; text{7} = 'Bessel filters have the worst frequency-domain characteristics (gradual cutoff), but excellent time-domain characteristics (near zero step response overshoot, keeps signal shape intact).'; text{8} = 'Butterworth filters have monotonic frequency-domain characteristics, like the Bessel, but with a sharper frequency cutoff. Their step response shows greater overshoot.'; text{9} = 'Chebychev filters have sharper cutoffs than the Butterworth at the expense of ripple in the passband (I) or stopband (II), and have a larger step response overshoot.'; text{10} = 'Elliptic filters have the sharpest cutoff but the worst time domain characteristics (highest step overshoot, greatest signal shape distortion).'; text{11} = ' '; text{12} = 'Parameter Definitions Figure'; text{13} = 'The plot shows the definitions for fc, Gp, and Gs for the various filter types and orders (e.g. the effect of odd/even order on asymptotic gain), but is inaccurate (e.g. number of ripples likely incorrect). Use the menu for an accurate frequency response.'; text{14} = ' '; text{15} = 'See the printed documentation for more details.'; % create help popup window msgbox(text,'Help: Specify Filter','none')