Multiplying the above by and evaluating the expected value, we have
Multiplying by and evaluating the expected value, we have
Kalman Filter Design: Lag d ( d >= 3)
To enhance readability, we use and interchangeably to denote the
posteriori state estimate. The slope is estimated as the mean of the last d
slope samples. This is given as
The state equation is therefore
The state variance is given by
1
11
2
+ 1 2 1
()−−−+ ()
d
X
d
var ˆttdvarXˆ
ˆˆ
ˆˆ
ˆˆˆ
|
|
XX
XX
d
X
d
X
d
X
tt t
ttd
tt t t d
−−
−−−
−−−−
=+
()−
=+
−
11
11
1111
11
XXˆˆ
d
ttd−−− 11 −
Xˆ
t
ˆ
Xt|t
−−() 1 rXXttt−−− 134 cov()ˆ ,ˆ ]
cov()XXˆtt−− − − 13 ,ˆ =+gt 1 [() 112 rt 1 cov()XXˆt t−− 23 ,ˆ +−()rt− 1 var()Xˆt− 3 −
Xˆ
t− 3
−−() 1 rXXttt−−− 124 cov()ˆ ,ˆ ]
cov()XXˆtt−− − − 12 ,ˆ =+gt 1 [() 112 rt 1 var()Xˆt− 2 +−()rt− 1 cov()XXˆt t−− 23 ,ˆ −
Xˆ
t− 2
rXˆ gY
−−() (^11) tt−− 14 ]+−()tt−− 11
ˆˆˆ
Xtt−− 11 | =+gt− 1 [() 112 rXt− − 1 t 2 +−()rXt− − 1 t 3 −
Spread Inversion 203