表明X(s)就是对x()e所做的傅立叶变换。由于e的引入,就 可以通过适当选择σ,使原来傅立叶变换不收敛的信号,其拉氏变换 存在。因此拉氏变换比傅立叶变换收敛性强,应用范围更广它是傅 立叶变换地推广

本章将采用与讨论连续时间完全相同 的思想方法,来研究离散时间周期信号 与非周期信号的频域分解问题。 DFS与CFS之间既有许多类似之处,也有 一些重大差别:主要是DFS是一个有限项 级数,具有周期性

基本思路:对LTI系统,由于其具有叠加性,齐 次性,时不变性,故而,如能实现将任意信号在时域分解为 简单单元信号的线性组合,那么只要得到LTI系统对基本 信号的响应,就可以利用系统的线性特性,将系统的输 出响应表示成系统对基本信号的响应的线性组合

5. Introduction (Chapter objectives) Amplitude modulation and single sideband Frequency and phase modulation Digitally modulated signals(OoK, BPSK, FSK, MSK MPSK, QAM, QPSK, a/4QPSK, and OFDM) Spread sprectrum and CDMa system

Introduction Basic signal properties(dc, rms, dBm. and power) Fourier transform and spectra Linear systems and linear distortion Bandlimited signal and sampling Discrete Fourier transform · Bandwidth of signal

Introduction Basic signal properties(dc, rms, dBm, and power) Fourier transform and spectra Linear systems and linear distortion Bandlimited signal and sampling Discrete Fourier transform Bandwidth of signal

Digital system: entity can process, transfer and store any kind of digital signals is Composed of individual digital logic circuits which are designed to perform specified function

信号与系统（英文版）_3 Fourier Series Representation of Periodic Signals

3.1 Discrete-Time Fourier Transform Definition- The discrete-time Fourier transform (DTFT) X(eio) of a sequence x[n] is given by jae In general,() is a complex function of the real variable and can be written as X(eio) Xre(eio) +j Xim(eio)

信号与系统（英文版）_6. Time and Frequency Characterization of Signals and Systems