Discrete-Time Signals: Time-Domain Representation Signals are represented as sequences of numbers, called samples Sample value of a typical signal or sequence denoted as x[n] with n being an integer in the range-∞≤n≤∞ ·x[n] defined only for integer values of and undefined for non-integer values

一、预备知识 二、双线性变换 三、低通R滤波器设计 四、高通、带通、带阻IIR数字滤波器设计 五、IR滤波器的谱变换 六、基于加窗傅立叶级数的FIR滤波器设计 七、数字滤波器的计算机辅助设计 八、用 Matlab进行数字滤波器设计

一、连续时间信号的抽样 二、带通信号的抽样 三、模拟低通滤波器设计 四、模拟高通、带通、带阻滤波器设计 五、反混叠滤波器设计 六、A/D转换器

一、傅立叶变换 一离散时间傅立叶变换(Discrete-Time- Fourier Transform,DTFT)(定义、收敛条件、性质)离散傅立叶变换( Discrete Fourier Transform,DFT)(定义、性质) 二、Z变换(定义、收敛条件、逆变换、性质)

Later in the course we shall review various methods of designing frequency-selective filters satisfying prescribed specifications · We now describe several loworder- FIR and IIR digital filters with reasonable selective frequency responses that often are satisfactory in a number of applications Copyright 2001, S. K. Mitra

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

An LtI discrete-time- system is completely characterized in the time-domain by its impulse response {h[n]} We consider now the use of the DTFT and the z-transform in developing the transform- domain representations of an Lti system Copyright 2001, S. K. Mitra

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

Comb Filters The simple filters discussed so far are characterized either by single passband and/or a single stopband There are applications where filters with multiple passbands and stopbands are required The comb filter is an example of such filters Copyright 2001, S. K. Mitra

2.2.1傅立叶分析 2.2.2周期矩形脉冲信号的频谱 2.2.3数字信道的特性 2.2.4基带传输、频带传输和宽带传输