Root Work Programming Misc Spectral Analysis

[dB]: 10log₁₀( |h|² ) = 20log₁₀( |h| )

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 y = fft(x);

 f = (0:length(y)-1)*(Fs-1)/length(y); % frequency vector

 Pf = (abs(y).^2)/length(y);

 Pf = (y.*conj(y))/length(y);

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  Absolute value	dB

  100			40
  10			20
  1			0
  0.1			-20
  0.01			-40

 octave - factor of two

 decade - factor of ten

 spatial frequency bandwidth:

 (logF_h - logF_l) / log2

 where F_h and F_l are the high- and low-frequency half-amplitude points, respectively.