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power spectrum estimation 有幾種方式,
/ w2 |' n3 a4 z n( x# K# TPeroidogram. P8 Q; t! E) L: b0 [2 _( h
Modified periodogram/ ]; U: H3 P# s( [" ~9 ~6 }$ k
Bartlett method& h6 ?) C0 g! y9 ^: l9 Z
Welch method
) i5 K) p/ `3 I" k$ q: [) X) }Blackman-Tukey method2 i) B& ~5 r% ]4 N/ v
8 C8 @8 q; y) I9 k/ v0 L* M6 T
若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias$ y5 N8 u! P9 I, x) W+ L& B
x : input sequence2 i8 r% g7 n1 b
n1 : starting index, x(n1)
3 F* G2 v6 L5 ^, {$ D) sn2 : ending index, x(n2)
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% [! i5 ]+ u$ r& efunction Px = per(x,n1,n2)
! _9 K6 U1 {4 N/ nx = x(;7 E! V: v' i) L4 t; e5 V
if nargin == 16 d& l) p$ | ~! v4 x! i
n1 = 1; n2 = length(x); end;
$ ]# S5 x7 b' o( qPx = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);" O" S. R2 a3 [0 i) B
Px(1) = Px(2); |
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