MATLAB: How can i remove this error in the program

freqz

% frequency response of a tree structured QMF Filters clf; %Type in the low pass filter coefficients B1=input('Filter coefficients='); B1=[ B1 fliplr(B1)]; %Generate the complementary high pass filter L=length(B1); for k=1:L; B2(k) = ((-1)^k) * B1(k); end %Determine the coefficients of the four filters B10=zeros(1, 2*length(B1)); B10([1 : 2: length(B10)])= B1; B11=zeroes(1, 2*length(abs(B2))); B11([1: 2: length(B11)]) = B2; C0=conv(B1,B10); C1=conv(B1,B11); C2=conv(B2,B10); C3=conv(B2,B11); % determine the frequency responses [H0z,w] = Freqz(C0,1,256); h0= abs(H0z); M0=20*Log10(h0); [H1z,w] = Freqz(C1,1,256); h1= abs(H1z); M1=20*Log10(h1); [H2z,w]=freqz(C2,1,256); h2= abs(H2z); M2=20*Log10(h2); [H3z,w] = Freqz(C0,1,256); h3= abs(H3z); M3=20*Log10(h3); plot(w/pi,M0,'-',w/pi,M1,'–', w/pi,M2,'–',w/pi,M3,'-'); grid xlabel('\omega/\pi'); ylabel('gain, dB')

Best Answer

It’s not necessary to run your code (I didn’t) to see the problem. MATLAB is case-sensitive, so convert ‘Freqz’ to ‘freqz’, ‘Log10’ to ‘log10’ and it should at least run.

Related Solutions

MATLAB: Using FFT, I want to plot a Magnitude Frequency Characteristic of a Digital FIR filter.

You can get Magnitude plot by running the below code

clc;
clear all;
b0 = 0.25;
b1 = [4 3 2 1];
b = conv(b1,b0);
freqz(b,256);

And from magnitude plot it is observed that the filter is a Low pass filter.

MATLAB: How to Design a lowpass filter by cascading 10 sections of the first-order IIR lowpass filter

hello

yes , conv is doing what your professor is asking , but this is the right way to use it (on the num and den part of your IIR filter)

%% low-pass IIR cascade K = 10 and compare with first-order low pass 
clc; clear all; close all;
w = 0:pi/255:pi;
% For Tenth-Order Low-Pass IIR | Transfer Function
num1 = [1 1]/1.5267;  % the /1.5267 is to make static gain = 1 (0 dB) (my suggestion)
den1 = [1 0.31];
% y = (num1) / (den1) ;
num = num1; % init

den = den1; % init
h1 = freqz(num, den, w);
g1 = 20*log10(abs(h1));
% PLOT CODE For first-Order
figure (1);
plot(w/pi,g1);grid minor; axis ([0 1 -100 5]);
xlabel("\omega /\pi");ylabel("Gain in dB");
title("LOW-PASS Cascade K=1 IIR Filter");
for i=1:9
    num = conv (num,num1);
    den = conv (den,den1);
end
h1 = freqz(num, den, w);
g1 = 20*log10(abs(h1));
% PLOT CODE For Tenth-Order
figure (2);
plot(w/pi,g1);grid minor; axis ([0 1 -100 5]);
xlabel("\omega /\pi");ylabel("Gain in dB");
title("LOW-PASS Cascade K=10 IIR Filter");

Best Answer

Related Solutions

MATLAB: Using FFT, I want to plot a Magnitude Frequency Characteristic of a Digital FIR filter.

MATLAB: How to Design a lowpass filter by cascading 10 sections of the first-order IIR lowpass filter

Related Question