2.延时特性: f()(t)(>F(s) 则f(t-10)(t-t6)>F(S)e 证明:[f(-4)(=10)]=[(-1)(-1=d 1-0=po f(t-toe dt h f(t)estor - st f(tes dt= fuse so 闪四 西南交通大学西南交通大学 2. 延时特性： f (t)e (t) « F (s) 则 0 ( ) ( ) ( ) 0 0 st f t t t t F s e « - - e - 证明： [ ] ò ¥ - - - e - = - e - 0 0 0 0 0 f (t t ) (t t ) f (t t ) (t t )e dt st L 0 0 0 0 0 ( ) ( ) ( ) ( ) 0 ( ) 0 0 st s st s t t t t st e f e d F s e f t t e dt f e d - - ¥ - - + ¥ - = ¥ - = = = - ò ò = ò - - - t t t t t t t