fir2007

# Fir2007

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Unformatted text preview: 17 depend on ©     © ¦   © !  #  #  #    rectangular Barlett Hann Hamming Blackman Kaiser , ¡¤ sidelobe level dB £ ¢ mainlobe width ¦ window ¡ ¢ Window Properties 0 1.33 3.86 4.86 7.04 – Tolerances (ripple) in passband and stopband are not separately determined. ECE 600 FIR Design T.H.E OHIO S ATE T UNIVERSITY Slide # 8 Window-based Design Steps: Generalized Linear Phase FIR Filters 1. Specify ideal frequency response 2. Select window to satisfy passband and stopband ripple specs ¦ to satisfy transition bandwidth (and noting constraints of types I–IV)   3. Select order ©  ¨ ¥§ £ ¤ £ IDTFT ¢ ¤ ¡ ¤  ¢¡   §¥ © ¦ §¥ ¨ delay (for causal ﬁnal result), and 4. Compute ideal impulse response with truncate via multiplication with shifted window sequence 5. Compute frequency response and compare to speciﬁcations  6. Iterate to meet specs with lowest order to affect transition width (and adjust Kaiser ) ©  (a) adjust order (b) adjust band-edge frequencies to shift magnitude response ECE 600 FIR Design T.H.E OHIO S ATE T UNIVERSITY Slide # 9 FIR Design Example 1 Speciﬁcations:           ¥  £  ¥ ¡ ¥ ¥ ¤ ¡ ¥ ¡ ¥ ¥ ¥  § §  Linear phase ECE 600 FIR Design T.H.E OHIO S ATE T UNIVERSITY Slide # 10 FIR Design Example 1, continued As=40;deltap=0.02;op=0.2;os=0.3; N=60;h=fir1(N,0.2494,hann(N+1)); % or >> h=sin(0.249*pi*[-30:30])./(pi*[-30:30]);h(31)=0.2494;h=h.*hann(61)'; [H,omega]=freqz(h,1,1024); subplot(2,1,1);plot(omega/pi,20*log10(abs(H)));grid;axis([0 1 -70 10]) subplot(2,2,3);plot(omega/pi,20*log10(abs(H)));grid;hold on; plot([0 op],20*log10(1+deltap)*[1 1],'r',[0 op],20*log10(1-deltap)*[1 1],'r'); axis([0.12 0.22 -0.5 0.5]);hold off; subplot(2,2,4);plot(omega/pi,20*log10(abs(H)));grid;hold on; plot([os 1],-40*[1 1],'r');axis([0.295 0.315 -50 -30]);hold off; 10 0 −10 −20 −30 −40 −50 −60 −70 0 0.1 0.2 0.3 0.4 0.5 0.5 0.6 0.7 0.8 0.9 1 0.305 0.31 0.315 −30 −35 0 −40 −45 −0.5 0.12 ECE 600 FIR Design 0.14 0.16 0.18...
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## This note was uploaded on 01/15/2014 for the course ECE 600 taught by Professor Clymer,b during the Winter '08 term at Ohio State.

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