jens
b31f3e7435
git-svn-id: http://moon:8086/svn/matlab/trunk@153 801c6759-fa7c-4059-a304-17956f83a07c
48 lines
1.8 KiB
Matlab
Executable File
48 lines
1.8 KiB
Matlab
Executable File
% ##################################################################################
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% ## Loesung: Entwurf rekursiver Filter ##
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% ##################################################################################
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fD = 1000; %Durchlassfrequenz (Hz)
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fS = 1400; %Sperrfrequenz (Hz)
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Rp = 0.5; %Durchlaßripple (dB)
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Rs = 30; %Sperrdaempfung (dB)
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fA = 8000; %Abtastfrequenz (Hz)
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Wp = 2*fD/fA; %Umrechnung in normierte Grenzfrequenzen
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Ws = 2*fS/fA;
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for typ=1:4
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if typ == 1;
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[n,Wn] = buttord(Wp,Ws,Rp,Rs); %Butterworth
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[b,a] = butter(n,Wn);
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FTyp = 'Butterworth';
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elseif typ == 2 ;
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[n,Wn] = cheb1ord(Wp,Ws,Rp,Rs); %Tschebyscheff Typ I
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[b,a] = cheby1(n,Rp,Wn);
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FTyp = 'Tschebyscheff Typ I';
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elseif typ == 3 ;
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[n,Wn] = cheb2ord(Wp,Ws,Rp,Rs); %Tschebyscheff Typ II
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[b,a] = cheby2(n,Rs,Wn);
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FTyp = 'Tschebyscheff Typ II';
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elseif typ == 4;
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[n,Wn] = ellipord(Wp,Ws,Rp,Rs); %Cauer
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[b,a] = ellip(n,Rp,Rs,Wn);
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FTyp = 'Cauer';
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else;
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error('Irgendwas stimmt nicht...');
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end;
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[H,W]=freqz(b,a,512);
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TitleString = sprintf('Filtertyp: %s Ordnung: %d', FTyp, n);
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figure; plot(W/pi,abs(H)); grid; title(TitleString);
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xlabel('Omega/pi');ylabel('|H(exp(j*Omega))|'); axis([0 1 0 1.2]);
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xline=[Wp Wp];yline=[0 10.^(-Rp/20)]; line(xline,yline,'linestyle','--');
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xline=[0 Ws]; yline=[1 1]; line(xline,yline,'linestyle','--');
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xline=[0 Wp]; yline=[10.^(-Rp/20) 10.^(-Rp/20)];line(xline,yline,'linestyle','--');
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xline=[Ws Ws];yline=[10.^(-Rs/20) 1];line(xline,yline,'linestyle','--');
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xline=[Ws 1]; yline=[10.^(-Rs/20) 10.^(-Rs/20)];line(xline,yline,'linestyle','--');
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figure; zplane(b,a); title(TitleString); xlabel('Realteil');
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ylabel('Imaginaerteil');
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end;
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% ##### EOF #####
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