I want to change Kaiser Window parameters

Question

Zaref Li 2024-1-5

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2066876-i-want-to-change-kaiser-window-parameters

回答： Hassaan 2024-1-16

在 MATLAB Online 中打开

Hello everyone,

I am designing ideal filter using Kaiser window. I give filter requirements :

I wrote this code. But how can I change the parameters?

A1 = 40;    % Stopband attenuation in dB
A2 = 15;    % Passband attenuation in dB
delta_w = 0.2 * pi;   % Transition band width
omega_c1 = 0.3 * pi;  % Lower critical frequency
omega_c2 = 0.5 * pi;  % Upper critical frequency
% Design Filter using Kaiser Window
N = ceil((A1 - 7.95) / (2.285 * delta_w));   % Estimate filter order
beta = kaiserbeta(A2);  % Calculate Kaiser window beta parameter
h = fir1(N, [omega_c1, omega_c2], 'bandpass', kaiser(N+1, beta)); % Design filter
% Impulse Response Plot
figure;
stem(h);
title('Impulse Response h[n]');
xlabel('n');
ylabel('h[n]');
% Frequency Response Plot
[H, w] = freqz(h, 1, 1024);  % Calculate frequency response
H_mag = 20*log10(abs(H));     % Magnitude in dB
figure;
plot(w/pi, H_mag);   % Plot frequency response
title('Magnitude Frequency Response');
xlabel('Normalized Frequency (\omega/\pi)');
ylabel('Magnitude (dB)');
% Check gains at critical frequencies
omega = [omega_c1, omega_c2];
[H_c, ~] = freqz(h, 1, omega);
gains = 20*log10(abs(H_c)); % Gains in dB
disp('Gains at critical frequencies:');
disp(gains);

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Sulaymon Eshkabilov 2024-1-5

编辑：Sulaymon Eshkabilov 2024-1-5

kaiserbeta() is a function or what that is missing

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Answer 1

Hassaan 2024-1-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2066876-i-want-to-change-kaiser-window-parameters#answer_1390731

在 MATLAB Online 中打开

A1 = 60; % New stopband attenuation in dB

A2 = 20; % New passband attenuation in dB

delta_w = 0.15; % New normalized transition band width

omega_c1 = 0.25; % New normalized lower critical frequency

omega_c2 = 0.45; % New normalized upper critical frequency

% Estimate filter order and beta using kaiserord

[N, beta] = kaiserord([omega_c1, omega_c2], [0, 1], [10^(-A2/20), 10^(-A1/20)]);

% Design Filter using Kaiser Window

h = fir1(N, [omega_c1, omega_c2], kaiser(N+1, beta)); % Design filter

% Impulse Response Plot

figure;

stem(h);

title('Impulse Response h[n]');

xlabel('n');

ylabel('h[n]');

% Frequency Response Plot

[H, w] = freqz(h, 1, 1024); % Calculate frequency response

H_mag = 20*log10(abs(H)); % Magnitude in dB

figure;

plot(w/pi, H_mag); % Plot frequency response

title('Magnitude Frequency Response');

xlabel('Normalized Frequency (\omega/\pi)');

ylabel('Magnitude (dB)');

% Check gains at critical frequencies

omega = [omega_c1, omega_c2];

[H_c, ~] = freqz(h, 1, omega*pi);

gains = 20*log10(abs(H_c)); % Gains in dB

disp('Gains at critical frequencies:');

Gains at critical frequencies:

disp(gains);

-5.5498 -5.5691

I've removed the pi factor from the critical frequencies omega_c1 and omega_c2 to normalize them correctly to the range [0, 1]. This should resolve the error, and your Kaiser window-based filter will be designed based on the updated filter specifications with normalized frequencies.

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