求达人帮我分析下FIR滤波器的设计
题目是这个样子的：设计FIR滤波器（低通，四种窗函数， fs＝1200Hz, 截止频率300Hz,
阶数自选, 画频率特性并分析比较)。
最好的话，能够帮我解决一下，实在是隔行如隔山~一点不通啊。。。
多谢~~ 谁知道阻带频率和题目中的关系？ 这个是我用工具箱做的。希望对后来人有帮助。clear;
Fs = 1200;% Sampling Frequency
N = 19; % Order
Fc = 300; % Cutoff Frequency
flag = 'scale';% Sampling Flag
Beta = 0.5; % Window Parameter
%% 凯撒窗%%
% Create the window vector for the design algorithm.
win = kaiser(N+1, Beta);
% Calculate the coefficients using the FIR1 function.
b= fir1(N, Fc/(Fs/2), 'low', win, flag)
= freqz(b,1,2048,1200);
figure;
plot(f,20*log10((abs(h))))
title('凯撒窗')
%% 矩形窗%%
% Create the window vector for the design algorithm.
win = rectwin(N+1);
% Calculate the coefficients using the FIR1 function.
b= fir1(N, Fc/(Fs/2), 'low', win, flag)
= freqz(b,1,2048,1200);
figure;
plot(f,20*log10((abs(h))))
title('矩形窗')
%% 海明窗%%
% Create the window vector for the design algorithm.
win = hamming(N+1);
% Calculate the coefficients using the FIR1 function.
b= fir1(N, Fc/(Fs/2), 'low', win, flag)
= freqz(b,1,2048,1200);
figure;
plot(f,20*log10((abs(h))))
title('海明窗')
%% 汉宁窗%%
% Create the window vector for the design algorithm.
win = hann(N+1);
% Calculate the coefficients using the FIR1 function.
b= fir1(N, Fc/(Fs/2), 'low', win, flag)
= freqz(b,1,2048,1200);
figure;
plot(f,20*log10((abs(h))))
title('汉宁窗')
%% 布莱克曼窗%%
% Create the window vector for the design algorithm.
win = blackman(N+1);
% Calculate the coefficients using the FIR1 function.
b= fir1(N, Fc/(Fs/2), 'low', win, flag)
= freqz(b,1,2048,1200);
figure;
plot(f,20*log10((abs(h))))
title('布莱克曼窗')
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