证明: E(X,=E Acos(ct)+Bsin(ct) (s, t)=ELAcos(ct )+Bsin(ct)LAcos()+B sin(s)I E[A' cos(cs)cos(ct)+ AB cos(ct)sin(cs)+ AB sin(ct)cos(cs +B sin (ct sin(cs )1 cos(cs)cos(ct)sin(ct) sin(cs)=cosc(t-s) (x}均值为0,r(2)只与有关,所以宽平稳 回总目录回本章目录证明： E X E A ct B ct ( t ) = + =   cos sin 0 ( ) ( )   ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) 2 2 , cos sin cos sin [ cos cos cos sin sin cos sin sin ] cos cos sin sin cos ( ) r s t E A ct B ct A cs B cs E A cs ct AB ct cs AB ct cs B ct cs cs ct ct cs c t s = + +         = + + + = + = − Xt  均值为0， r s t ( , ) 只与t-s有关，所以宽平稳。 回总目录 回本章目录