|
power spectrum estimation 有幾種方式,+ W7 K5 I% F# D
Peroidogram- }# a8 V! ^" L m6 Y% _0 p
Modified periodogram9 t8 v" ]& \* r h
Bartlett method, S: B* E, l& a( c
Welch method
3 H2 `& }* p0 Y7 w/ kBlackman-Tukey method3 a1 c( I7 a- F! D* l- S2 L; J ?
5 y5 U. e. A2 u5 g+ V0 E若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias
" v4 r3 g, X# ~ z$ k# x qx : input sequence7 n8 B1 K' G0 @- m6 H5 k, c) b
n1 : starting index, x(n1)9 W! R5 s! L8 C: {1 E+ r* R
n2 : ending index, x(n2)) b6 E1 B+ P: U% G, N* y& f u
# S7 H3 s+ B! @) K: A
function Px = per(x,n1,n2) e5 j) n+ \# s
x = x(;
1 G6 c& i# N, J5 X- Gif nargin == 1
$ t) w# `9 ^0 B% b n1 = 1; n2 = length(x); end;* D% d: a; u- j7 {# O
Px = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);" R& L' u2 E& Z
Px(1) = Px(2); |
|