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normalize amplitudes across FFT window functions

This commit is contained in:
Christian Daniel 2012-06-03 21:57:41 +02:00
parent 0355ef0f38
commit fe6744ce1e
1 changed files with 6 additions and 4 deletions
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10
dsp/fftwindow.h
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@ -48,24 +48,26 @@ private:
static inline Real bartlett(Real n, Real i)
{
return (2.0 / (n - 1.0)) * ( (n - 1.0) / 2.0 - fabs(i - (n - 1.0) / 2.0));
// amplitude correction = 2.0
return (2.0 / (n - 1.0)) * ( (n - 1.0) / 2.0 - fabs(i - (n - 1.0) / 2.0)) * 2.0;
}
static inline Real blackmanHarris(Real n, Real i)
{
return 0.35875 - 0.48829 * cos((2.0 * M_PI * i) / n) + 0.14128 * cos((4.0 * M_PI * i) / n) - 0.01168 * cos((6.0 * M_PI * i) / n);
// amplitude correction = 2.79
return (0.35875 - 0.48829 * cos((2.0 * M_PI * i) / n) + 0.14128 * cos((4.0 * M_PI * i) / n) - 0.01168 * cos((6.0 * M_PI * i) / n)) * 2.79;
}
static inline Real hamming(Real n, Real i)
{
// amplitude correction = 1.855, energy correction = 1.586
return 0.54 - 0.46 * cos((2.0 * M_PI * i) / n);
return (0.54 - 0.46 * cos((2.0 * M_PI * i) / n)) * 1.855;
}
static inline Real hanning(Real n, Real i)
{
// amplitude correction = 2.0, energy correction = 1.633
return 0.5 - 0.5 * cos((2.0 * M_PI * i) / n);
return (0.5 - 0.5 * cos((2.0 * M_PI * i) / n)) * 2.0;
}
static inline Real rectangle(Real, Real)