Find the closest freq in a filterbank
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- Get the center frequencies of all the filters in the filter bank using the getCenterFrequencies function.
- Calculate the absolute difference of center frequency and center frequencies from 1st step.
- Get the sorted indices of the difference and select the 1st 3 indices. These are the filter numbers which have closest center frequencies.
- Use these filter numbers to get the desired output.
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Hi @S,
To achieve frequency-based filtering in MATLAB, where the filter selection is not fixed but rather determined by the proximity of the filter's frequency response to the desired input frequency, first, you need to know that each filter has a specific frequency response that can be obtained using the freqz function. This function returns the frequency response of a filter given its coefficients. So, instead of using a predetermined filter number, iterate through all available filters. For each filter, compute its frequency response and determine how close it is to the desired input frequency. Afterwards, maintain a variable to track the minimum difference between the input frequency and the frequencies of the filters. The filter that yields the smallest difference will be selected for filtering the output signal. Once the closest filter is identified, we will apply it to the output signal using the filter function. Here is a complete example that demonstrates it.
% Generate or load the 'output_signal' variable output_signal = your_output_signal_generation_function(); % Replace with actual signal generation code
% Define input frequency input_frequency = 0.3; % Example input frequency
% Initialize variables for closest filter selection num_filters = size(output_signal, 2); % Assuming output_signal has filters as columns min_difference = Inf; closest_filter_number = 1;
% Iterate over all filters to find the closest one for filter_number = 1:num_filters % Obtain frequency response for the current filter [h, f] = freqz(output_signal(:, filter_number));
% Calculate the difference between current filter response and input frequency difference = abs(f - input_frequency);
% Update closest filter if the current one is closer if min(difference) < min_difference min_difference = min(difference); closest_filter_number = filter_number; end end
% Obtain the frequency response for the closest filter [h_closest, ~] = freqz(output_signal(:, closest_filter_number));
% Apply frequency filtering using the closest filter filtered_output_closest = filter(h_closest, 1, output_signal);
% Display the results disp(['The closest filter number is: ', num2str(closest_filter_number)]);
Integrate this code into your existing code
So, at this point, integrate this code snippet into your existing MATLAB script. Simply place it below your current filtering logic. Make sure that the output_signal variable is correctly defined and that the number of filters is accurately represented in the num_filters variable.
This approach should allow you now for a flexible and dynamic selection of filters based on the input frequency, enhancing the adaptability of your filtering process.
Should you have any further questions or require additional modifications, please feel free to reach out.
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