Digital filter design

Hello All Gentleperson,

I am an old user of Matlab and now I need to use it often. Could you remind me how to build the filters in the follow in the matlab:

1. Number of Tap of FIR 2. IIR 3. SINC and SINC3

Thanks, Shanshan

Answer 1

[Sulaymon Eshkabilov]

%% Saw-tooth signal generation:
fs=25; t=0:1/fs:13;
% Saw-tooth like signal S(t) is generated:
S=sawtooth(t);
% Add White Gaussian noise to the signal S(t):
SN=awgn(S, 5,'measured'); 
% Note: SN noise added sgnal to simulate the FIR filter
%% FIR filter design
% Lowpass FIR filter design:
Fc = 0.12;              % Cut off frequency
N  = 12;                % FIR filter order
Hf = fdesign.lowpass('N,Fc',N,Fc);
% Window method based filter design:
Hd(1)=design(Hf, 'window','window',{@chebwin,20});
Hd(2)=design(Hf, 'window','window',@hamming);
% Recall filter design tool:
HFvt=fvtool(Hd, 'Color', 'White');
% Windowing with Chebyshev window: 
Yt1=filter(Hd(1), SN);
% Windowing with Hamming window: 
Yt2=filter(Hd(2), SN); 
%% Buttorworth: High-pass/Low-pass/Band-pass
[B,A] = BUTTER(N,Wn,'high') % designs a high-pass filter.
 [B,A] = BUTTER(N,Wn,'low')  % designs a low-pass filter.
 [B,A] = BUTTER(N,Wn,'bandpass') % bandpass filter: Wn =[W1 W2]