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有人能告诉我如何使用 MATLAB 实现谐波乘积谱，以在存在谐波的情况下找到音符的基频吗？我知道我应该对我的信号进行多次下采样（当然是在执行 fft 之后），然后将它们与原始信号相乘。

说我的fft信号是“FFT1”

那么代码大致是这样的

hps1 = downsample(FFT1,2);
hps2 = downsample(FFT1,3);

hps = FFT1.*hps1.*hps2;

这段代码正确吗？？？我想知道我是否正确地进行了下采样，并且由于每个变量的长度不同，因此将它们相乘会导致矩阵维度错误。我真的需要一些真正的快速帮助，因为它对于项目工作...真的很绝望....谢谢提前....

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OK you can't do "hps = FFT1.*hps1.*hps2;" for each downsampled data, do you have different sizes ...

I did a example for you how make a very simple Harmonic Product Spectrum (HPS) using 5 harmonics decimation (downsample), I just test in sinusoidal signals, I get very near fundamental frequency in my tests.

This code only shows how to compute the main steps of the algorithm, is very likely that you will need improve it !

Source:

%[x,fs] = wavread('ederwander_IN_250Hz.wav');

CorrectFactor = 0.986;
threshold = 0.2;

%F0 start test
f  = 250;
fs = 44100;

signal= 0.9*sin(2*pi*f/fs*(0:9999)); 
x=signal';

framed = x(1:4096);

windowed = framed .* hann(length(framed));

FFT = fft(windowed, 4096);

FFT = FFT(1 : size(FFT,1) / 2);

FFT = abs(FFT);

hps1 = downsample(FFT,1);
hps2 = downsample(FFT,2);
hps3 = downsample(FFT,3);
hps4 = downsample(FFT,4);
hps5 = downsample(FFT,5);

y = [];

for i=1:length(hps5)

      Product =   hps1(i)  * hps2(i) * hps3(i) * hps4(i) * hps5(i);
      y(i) = [Product];
end

[m,n]=findpeaks(y, 'SORTSTR', 'descend');

Maximum = n(1);

 %try fix octave error
if (y(n(1)) * 0.5) > (y(n(2))) %& ( ( m(2) / m(1) ) > threshold )

    Maximum  = n(length(n));

end

F0 =  ( (Maximum / 4096) * fs ) * CorrectFactor 

plot(y)

HPS usually generates an error showing the pitch one octave up, I change a bit a code, see above :-)

于 2013-11-04T14:54:22.147 回答