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power spectrum estimation 有幾種方式,, \$ [0 [; I. O; L/ z
Peroidogram6 N' d8 `* N/ [0 v* J8 P9 Q- \% u! c
Modified periodogram0 `9 _& A5 S( l ^ k$ @# I
Bartlett method
/ D/ F w7 E, F! M1 WWelch method
& @) R% \0 y$ _ RBlackman-Tukey method4 [2 u2 J6 L; \
1 b: e r5 n4 g2 `) x
若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias' f1 X% C) y1 j8 o. r( N
x : input sequence
) Q4 R2 b4 C4 F% ]# gn1 : starting index, x(n1)& m9 X6 O$ G* L Q) L6 T f
n2 : ending index, x(n2)
1 d! p5 M1 P0 `5 u0 u' z4 [2 X @. O
]- Q1 K$ v: T$ h+ [( y: k2 c6 ofunction Px = per(x,n1,n2)
2 P7 H5 s$ z4 {; s9 Jx = x(;: M1 h- Q3 \3 ^& q9 M9 @8 n
if nargin == 1
$ Q9 l. d1 V. T; o n1 = 1; n2 = length(x); end;- x3 q) V+ D/ U# s
Px = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);
0 b& v+ Q# ^4 s. a8 oPx(1) = Px(2); |
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