加窗插值fftmatlab程序

以下是一个加窗插值FFT的Matlab程序：

function [freq, P] = windowed_fft(x, fs, window_len, overlap, window_type)
% x: input signal
% fs: sampling frequency
% window_len: length of the window
% overlap: overlap between windows
% window_type: type of window function to use (e.g. 'hamming', 'hanning', 'blackman', 'rectwin', etc.)

% calculate the number of samples per window
n_samples = length(x);
n_per_window = floor(window_len * fs);

% calculate the number of overlapping samples per window
n_overlap = floor(n_per_window * overlap);

% create the window function
window = feval(window_type, n_per_window);

% calculate the number of windows
n_windows = floor((n_samples - n_overlap) / (n_per_window - n_overlap));

% initialize output arrays
P = zeros(n_per_window/2+1, n_windows);
freq = linspace(0, fs/2, n_per_window/2+1);

% loop over each window
for i = 1:n_windows
    % calculate the start and end indices of the current window
    start_idx = (i-1) * (n_per_window - n_overlap) + 1;
    end_idx = start_idx + n_per_window - 1;
    
    % apply the window function to the current window
    windowed_signal = x(start_idx:end_idx) .* window;
    
    % calculate the FFT of the windowed signal
    fft_result = fft(windowed_signal);
    
    % calculate the power spectrum of the FFT
    P(:,i) = abs(fft_result(1:n_per_window/2+1)).^2 / (n_per_window*fs);
end

% take the mean of the power spectra across all windows
P = mean(P, 2);
end

该程序接受输入信号x，采样频率fs，窗口长度window_len，重叠overlap和窗口类型window_type，并返回频率和功率谱。程序通过在每个窗口上应用窗函数，并对窗口之间的重叠进行FFT来计算功率谱。最后，程序将所有窗口的功率谱取平均值以获得最终功率谱。