Chapter l Signals and Systems 51.2 Transformations of the independent variable 51.2. 1 Examples of transformations of the independent variable 1. Time shifte(时移) f→>t-to x()→x(-t0) n→n-n0 Example 1 t10≤t≤t1 x()= 0 otherwise Please indicate 16
16 Chapter 1 Signals and Systems §1.2 Transformations of the independent variable §1.2.1 Examples of transformations of the independent variable 1. Time shift( 时移) 0 t → t − t n → n − n0 ( ) ( ) 0 x t → x t − t x n → x n − n0 Example 1 x(t) = 1 t / t 0 1 t t 0 otherwise Please indicate ( ) 0 x t − t
Chapter l Signals and Systems 时移对信号的影响 x(-1)与x()波形相同 6>0相当于x()右移(延迟)t tn<0相当于x()左移(超前)t 2. Time reversal(时域反折) t→-tn→-n x(t)is a reflection of x(t) about t=0 17
17 Chapter 1 Signals and Systems ( ) 0 x t −t 与 x(t) 波形相同 t 0 0 相当于 x(t) 左移（超前） to 2. Time reversal( 时域反折) t → −t n → −n x(-t) is a reflection of x(t) about t=0 t 0 0 相当于 x(t) 右移（延迟） to 时移对信号的影响
Classification of signals(信号的分类) 1. Continuous Time(CT)and discrete time (dt)signals 连续时间信号和离散时间信号 2. Periodic and aperiodic signals 周期信号和非周期信号 3. Energy and power Signals 能量信号和功率信号(能量有限信号和能量无限信号) 4. Deterministic and Stochastic(nondeterministic) Signals 确定性信号随机信号(非确定性信号)
18 Classification of signals （信号的分类） 1.Continuous Time（CT）and discrete time（DT） signals 连续时间信号和离散时间信号 2. Periodic and Aperiodic Signals 周期信号和非周期信号 3. Energy and Power Signals 能量信号和功率信号(能量有限信号和能量无限信号) 4. Deterministic and Stochastic (nondeterministic) Signals 确定性信号随机信号(非确定性信号)