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power spectrum estimation 有幾種方式,
- m* D& n' M: |; n+ v. SPeroidogram& e+ c0 R6 U; \- `* R: w! d
Modified periodogram5 W+ _0 _; c4 [/ A4 N ^
Bartlett method- p8 y- C. R; L. v. \" O3 Z
Welch method$ |9 P+ F, x+ N$ k3 M" N
Blackman-Tukey method
; s# R" n. h# C5 j) O) I% o* A) _, C D* `
若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias
8 M# N/ M& P6 ~- t; I, n: Y3 yx : input sequence; \0 E( ~0 \$ d3 j+ g' _
n1 : starting index, x(n1)9 K7 c$ N3 @& l5 S5 m! h) T
n2 : ending index, x(n2)5 p* k/ H% m! I' N
: d: J& ]' {7 A( G4 G' ufunction Px = per(x,n1,n2)
) c8 u2 d7 y5 A" }1 Y+ b5 z( xx = x(;" Q3 u' y: J* i$ z, \; u% {( M( [
if nargin == 11 y5 U7 q+ J( {5 P2 ]; t
n1 = 1; n2 = length(x); end; }7 P' O& B2 J2 f
Px = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);7 D; q/ j% u* r# X# z
Px(1) = Px(2); |
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