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power spectrum estimation 有幾種方式,
8 ~' C, d) ?9 d8 Y% U* `; K* h4 qPeroidogram
9 i4 R( y+ O- F+ E$ v2 `Modified periodogram
: e; a( m" M: {* N) ?. v) wBartlett method2 m" |. h( Z* _3 `" D/ {5 ?
Welch method r/ n" ` M( ?6 i6 O$ F
Blackman-Tukey method
6 |+ c; `' k! E: F! k- X
1 v* {. s7 U7 Y( v& O若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias
0 K( e0 U8 z$ y2 M; s* _. ux : input sequence, z! ]4 O/ G, k
n1 : starting index, x(n1)* W& q2 y3 _9 w7 j6 m4 g# ]
n2 : ending index, x(n2)2 |( T0 Z$ i; q& V/ h& S+ H& \- K
u1 m* N" e( E$ K- {
function Px = per(x,n1,n2)
3 C! U, t$ J& Ox = x(;- a$ ]( z$ B9 c# D- m, Q; B" v
if nargin == 1+ z* r* ]* `: t4 }
n1 = 1; n2 = length(x); end;
9 A8 E7 \! |+ \& N8 K( r5 cPx = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);. |4 x& U, M5 Z5 K( @& B
Px(1) = Px(2); |
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