다음의 CEMTool코드에 주어진 사양을 갖는 타원형 대역통과 필터를 설계해보자.

ex8_29.cem

/* 
Chapter 8: Example 8.29            
Elliptic Bandpass Filter Design:             
Use of the ELLIP function
*/
 
 /* Digital Filter Specifications:  */         	/* Type: Elliptic Bandpass */
 ws = [0.3*pi 0.75*pi];                    	/* Dig. stopband edge frequency */
 wp = [0.4*pi 0.6*pi];                     	/* Dig. passband edge frequency */
 Rp = 1;                           		/* Passband ripple in dB */
 As = 40;                             		/* Stopband attenuation in dB */
 
 /* Calculations of Elliptic Filter Parameters: */
 [N,wn] = ellipord(wp/pi,ws/pi,Rp,As);
 
 /* Digital Elliptic Bandpass Filter Design: */
 [b,a] = ellip(N,Rp,As,wn);
 
 /* Cascade Form Realization: */
 [b0,B,A] = drt2cas(b,a) 
 
% Plotting:
figure;
 
subplot(1,1,1)[db,mag,pha,grd,w] = mfreq_z(b,a);
subplot(2,2,1);plot(w/pi,mag);title("Magnitude Response")xtitle("frequency in pi units");
 
subplot(2,2,3);plot(w/pi,db);title("Magnitude in dB")xtitle("frequency in pi units");
 
subplot(2,2,2);plot(w/pi,pha/pi);title("Phase Response")xtitle("frequency in pi units");ytitle("phase in pi units") 
subplot(2,2,4);plot(w/pi,grd);title("Group Delay")xtitle("frequency in pi units"); ytitle("samples")