数字信号处理吴镇扬习题解答.pdf

1-4 xa 1 (t) cos 2πt, xa 2 (t) −cos 6πt, xa 3 (t) cos10πt ,Ω 8π ,,. x (t), x (t), x (t) s a 1 a 2 a 3 . 8π 8π 8π w 10 :w1 2π = ,; w2 6π = ,; 3 π = ,. 2 2 2 1-13 , y (n ) , x (n) ,?? n (1)y (n ) 2x (n ) +5 (3)y (n ) ∑x (m ) ) m=−∞ 心 : 中 T ax n +bx n ax n =+bx n + 训 (1) [ 1( ) 2 ( )] 2[ 1( ) 2 ( )] 5 培 =+ + + − − + a[2x1 (n) 5] b[2x2 (n) 5] 5a 5b 5 信 ; =+ − − + ≠ + aT x n bT x n a b aT x n bT x n [ 1 ( )] [ 2 ( )] 5 5 5 [ 1 ( )] [ 2 ( )] 通 邮 x (n −n ) , 0 南 ( T[x(n −n )] 2x(n =−n ) +5 y(n =−n ) . 0 0 0 育 教n (2)T[ax (n) +bx (n)] ∑[ax (m) =+bx (m)] 1 2 1 2 途 m=−∞ n n ; 通 a ∑x (m) =+b ∑x (m) ay (n) =+by (n) 1 2 1 2 m=−∞ m=−∞ n n−n0 T[x(n −n )] ∑x(m =−n ) ∑x(m) y(n −n ) . 0 0 0 m=−∞ m=−∞ 1-16 : (1)y (n ) g (n )x (n ),g (n ) n (2)y (n ) ∑x (k ),n =n0 k n 0 n (4)h(n) 0.5 u(n) :