|
power spectrum estimation 有幾種方式,& B# t$ ^( H( J! X& Z7 K& `
Peroidogram
' u+ \, n( k- o9 lModified periodogram) ^# I g* F& A, T) Y+ Y( p
Bartlett method
0 Q5 P4 ]9 x. ^5 q2 tWelch method8 W; f4 C0 _- r2 e5 R* w( e9 V$ I
Blackman-Tukey method
" ^8 ], Q% y( y! Q' L7 p- f, y
7 e1 ^' v) X/ ^9 x# D若用simple Peroidogram m file 方式如下,estimated 跟 actual 會有Bias( c, g" {- b! t; {+ U! ]
x : input sequence
. c1 ^7 Z3 Z. m7 p4 mn1 : starting index, x(n1)
& o9 T! t. r$ k7 g5 [n2 : ending index, x(n2)0 k1 w& f& D" Z; S' \
; W0 P0 m) m* a: z+ z: l* ]6 {/ U
function Px = per(x,n1,n2)+ Y) x9 v2 B+ P+ o) d" k
x = x(;
: p4 g; }; L1 V) x% U. w- Oif nargin == 1
- [/ x; q2 j) L& [: m1 T* H! q n1 = 1; n2 = length(x); end;; k- T: k6 ]3 u3 _7 m, U) z
Px = abs(fft(x(n1:n2),1024)).^2/(n2-n1+1);" B: S8 |( v" P- P+ [+ p1 p$ \! @
Px(1) = Px(2); |
|