www.gusucode.com > dsp 案例源码程序 matlab代码 > dsp/DesignOfTheAllpassMappingFilterExample.m

    %% Design of the allpass mapping filter
% This example shows how to design allpass mapping filter, changing the complex bandpass filter with the band edges at $W_{o1}=0.2$ and $W_{o2}=0.4$ to
% the new band edges of $W_{t1}=0.3$ and $W_{t2}=0.6$.
% Find the frequency response of the allpass mapping filter:

% Copyright 2015 The MathWorks, Inc.


Wo = [0.2, 0.4]; Wt = [0.3, 0.6]; 
[AllpassNum, AllpassDen] = allpassbpc2bpc(Wo, Wt);
[ha, f] = freqz(AllpassNum, AllpassDen, 'whole');
plot(f/pi,-angle(ha)/pi, Wt, Wo, 'ro'); title('Mapping Function Wo(Wt)'); 
xlabel('New Frequency, Wt'); ylabel('Old Frequency, Wo');