a(_)=10lg =10g(1+K(22 H(C2) 2 2 AK(八2)=10101 2n 2 a(2) =1010-1 1010-1 0 0 x(2n) 10 Ig 30-1 H(Q2) C(92 2 1010-1 H(j2)H(-j2) S10 ） 2 2 10lg(1 ( ) ( ) 1 ( ) 10lg = +    = K j H j  n K j 2 0 1 0 ( ) 2 ( ) 10 1            = − =   10 1 1 0 2 ( ) 0 = −           p n p  10 1 10 ( ) 2 0 = −           s n s  n = ?           − − =   s p s p n lg 10 1 10 1 lg 10 ( ) 10 ( )   ( ) ( ) 1 1 ( ) 2 0 2 =  −            +  = H j H j H j n