同济大学：《数字信号处理（DSP）》课程教学资源（PPT课件讲稿）第三章 离散傅里叶变换（6/7）

同济大学：《数字信号处理（DSP）》课程教学资源（PPT课件讲稿）第三章 离散傅里叶变换（7/7）

一、时域离散信号—序列

1-1 离散时间信号-序列 1-2 线性移不变系统 1-3 常系数线性差分方程 1-4 连续时间信号的抽样

一、FFT算法的基本思想

4-1引言 4-2按时间抽取(DIT)的FFT算法 4-3DIF的FFT算法 4-4FFT算法 4-5线性卷积的FFT算法

Transform-Domain Representation of Discrete-Time Signals Three useful representations of discrete-time sequences in the transform domain: Discrete-time- Fourier Transform(DTFT) YDiscrete Fourier Transform(DFT) z- -Transform

DTFT Properties Using the differentiation property of the DTFT given in Table 3.2, we observe that the DTFT of nx[n] is given by

Phase and Group Delays The output y[n] of a frequency-selective LTI discrete-time system with a frequency response(@) exhibits some delay relative to the input x[n] caused by the nonzero phase response 0(@) =arg{()} of the system

Stability Condition in Terms of the Pole Locations A causal lti digital filter is BIBO stable if and only if its impulse response h[n] is absolutely summable, i.e