%% Shift Complex Bandpass
% Design a prototype real IIR lowpass elliptic filter with a gain of about –3 dB at 0.5π rad/sample.

[b,a] = ellip(3,0.1,30,0.409);

%
% Create a complex passband from 0.25π to 0.75π.

[bc,ac] = iirlp2bpc(b,a,0.5,[0.25 0.75]);

%
% Move the bandpass to between –0.3π and 0.1π.

[num,den] = iirbpc2bpc(bc,ac,[0.25 0.75],[-0.3 0.1]);

%
% Compare the three filters in FVTool.

hvft = fvtool(b,a,bc,ac,num,den);
legend(hvft,'Prototype','Positive complex band','Target')

% Copyright 2012 The MathWorks, Inc.