I want to change Kaiser Window parameters

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);

[Sulaymon Eshkabilov]

kaiserbeta() is a function or what that is missing

Answer 1

[Hassaan]

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.

------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.