The Discrete-Time Unit Step Function 。Definition 1,n≥0 m=0.n<0
The Discrete-Time Unit Step Function • Definition 0, 0 1, 0 [ ] n n u n
The Discrete-Time Unit Step Function u[n] 1.099 n -4-3-2-1 01234
The Discrete-Time Unit Step Function
The Continuous-Time Unit Step Function ·Definition 1,t>0 u)=0,t<0
The Continuous-Time Unit Step Function • Definition 1, 0 ( ) 0, 0 t u t t
Continuous-time version of the unit-step function of unit amplitude. (t) -t 0
Continuous-time version of the unit-step function of unit amplitude
The Rectangular Pulse mw防-6小 rect(t)=u(t+0.5)-u(t-0.5)
The Rectangular Pulse 1, 0.5 rect( ) 0, 0.5 rect( ) ( 0.5) ( 0.5) t t t t u t u t
(a)Rectangular pulse x(t)of amplitude A and duration of 1 s,symmetric about the origin.(b)Representation of x(t)as the difference of two step functions of amplitude A,with one step function shifted to the left by and the other shifted to the right by %the two shifted signals are denoted by x1(f)and x2(f), respectively.Note that x(f)=x1(f)-x2(f). x()) x1(0 A -0.5 0 0.5 -1 -0.5 0 0.5 (a) (b) x2(I) A -1 -0.5 0 0.5 (c)
(a) Rectangular pulse x(t) of amplitude A and duration of 1 s, symmetric about the origin. (b) Representation of x(t) as the difference of two step functions of amplitude A, with one step function shifted to the left by ½ and the other shifted to the right by ½; the two shifted signals are denoted by x1 (t) and x2 (t), respectively. Note that x(t) = x1 (t) – x2 (t)