H( )
1
10 3
j 1
A( )
11 ( )
2
(10 3
)
( ) arctan( ) arctan(10 3 )
Uy 10A(1000)sin(1000t (1000)) 10 0.707sin(1000t 450) 7.07sin(1000t 450
)
4.11 解：A( )
1 ( )
2
( ) arctan( ) 1
10时，
A(10)
(0.05 10)
0.816
(10) arctan(0.05 10) 26.56
)
1
100时，
A(100 (0.05 100)
0.408
(100) arctan(0.05 100) 78.69
y(t) 0.5 0.816cos(10t 26.56 ) 0.2 0.408cos(100t 45 78.69 ) 0.408cos(10t 26.56
) 0.0816cos(100t 33.69
)
5.1 t)
e th(;(t 0, 0) 0;(t 0)
R
x( ) h(t) h(t )dt
e te (t )
dt
e
e
2 t
dt
e2
5.2 x(t) A1sin( 1t 1
2
) A2sin( 2t 2
2
)
