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power spectrum estimation 有幾種方式,0 \4 V, g/ S6 F9 I/ K9 J
Peroidogram: U. }) s' [ V5 r0 ~/ J- h
Modified periodogram7 `8 m2 y u0 x* O+ j
Bartlett method3 D- e: ]. [2 l; G7 W! i2 D
Welch method8 f% O9 B% O% V, @- r7 b8 I3 t
Blackman-Tukey method
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若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias3 S) J" w t4 T+ X" z2 d* e$ u! n5 T5 N
x : input sequence; [3 _1 R+ U1 G+ F8 l: Q7 ?
n1 : starting index, x(n1)
* H( X9 ~6 f! g8 In2 : ending index, x(n2)
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function Px = per(x,n1,n2)
# ]9 t* Y- L/ `/ } Q0 lx = x(;
. a, g" ?; F. d, nif nargin == 1" ^3 y3 W6 Z! Y7 I4 F! u2 |% Z
n1 = 1; n2 = length(x); end;% S& A& [! n7 N$ E; e# R
Px = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);
7 \1 Y2 n" q, n0 T' j& u% x5 \Px(1) = Px(2); |
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