信号处理导论（英）Chapter 3 Discrete-Time Systems.pptVIP

Chapter 3 Discrete-Time Systems 3.1 Input/Output Rules 3.2 Linearity and Time Invariance 3.3 Impulse Response * * 经过前两章讲的抽样和量化，模拟信号转化为数字信号，接下来数字信号输入到数字信号处理器中进行处理，并在输出端得到经过处理后的数字信号。很明显我们接下来的任务也相应地应该是对数字信号处理器（DSP）的研究。 1.研究数字信号处理器（DSP）的理论——离散时间信号与系统理论 将DSP看作一离散时间系统，在大多数情况下是将其视为线 性移不变（linear time-invariant =LTI)离散时间系统。 2.LTI 离散时间系统 * 一LTI 离散时间系统可以用它的单位冲激响应 来描述。 * LTI systems can be classfied into finite impulse response (FIR) or infinite impulse response (IIR) types depending on whether their impulse response has finite or infinite duration : FIR (Finite－Impulse－Response )： 是有限长序列 IIR (Infinite－Impulse－Response) ： 是无限长序列 A discrete-time systems , shows in Fig.3.1.1 , is a processor that transform an input sequence of discrete-time samples into an output sequence of samples ,according to some input/output rule that specifies how to compute the output sequence from the knowledge of the input sequence (p99 ) Thus,the I/O rule maps the input vector x into the output vector y according to some functional mapping y=H[x] For linear systems , this mapping becomes a linear transformation by a matrix H , y=Hx . For linear and time-invariant systems,the matrix H has a special structure being built in terms of the impulse response of the system. FIR DF 对输入的两种处理方法 sample-by-sample processing method: we may think of the I/O rule as processing the input samples one at a time: that is , , …… 2. block processing method: we think of the input sequence as a block or vector of signal samples being processed as a whole buy the system Example 3.1.1 ——Example 3.1.16 举了各种 input/output rules 的例子。 Example 3.1.3 : block processing Example 3.1.4 : sampling processing Example 3.1.5 : IIR DF Example 3.1.6 : IIR DF 的sampling processing algorithm