Fvtool for Octave

See file fvtool_for_octave.zip for fvtool.m script.

Source code

%% lets make lowpass filter (6th order, elliptic type) %[num,den]=butter(6,0.3); [num,den]=ellip(6,1,40,0.3); figure(1) fvtool(num,den); title('Frequency response of lowpass filter') % Note: default axes are linear frequency and gain in times %% you may switch axis mode to dB and logarithmic frequency figure(2) fvtool(num,den,'MagScale','Logarithmic','FreqScale','Logarithmic'); title('Frequency response (Logarithmic axes)') % Note: you may use shortenings like ...'Mag', 'Log', 'Freq', 'Log'... %% you may also set ranges for both axes % lets zoom to pass band frequency response figure(3) fvtool(num,den,'AxisX',[0.01 0.3],'AxisY',[-1.5 0.5],'MagScale','Logarithmic','FreqScale','Logarithmic'); title('Setting axis range (passband response)') %% and more % lets zoom to stop band frequency response figure(4) fvtool(num,den,'AxisX',[0.3 1],'AxisY',[-90 -35],'MagScale','Logarithmic','FreqScale','Logarithmic'); title('Setting axis range (stopband response)') %% you may display different responses % such as phase response figure(5) fvtool(num,den,'Display','Phase'); % or phase delay response figure(6) fvtool(num,den,'Display','PhaseDelay'); % or group delay response figure(7) fvtool(num,den,'Display','GroupDelay'); %% display multiple filter response and specifying samplerate is possible [num0,den0]=butter(6,0.3); [num1,den1]=butter(6,[0.3 0.7]); [num2,den2]=butter(6,0.7,'high'); figure(8) fvtool(num0,den0,num1,den1,num2,den2,'Fs',48000); title('Display multiple filters, specufy sample rate')

Execution results


Generated graphics