5.1 均匀速率取样过程的数学说明 到目前为止,我们主要讨论的是数字信号,即按顺序排列的数码。然而,许多实际系统是用随时间连续变化的过程来表示其特征的。例如,立体声系统的声音输出表示声压波随时间的连续变化。按这种方式变化的信号称为模拟信号。模拟信号的例子示于图5-1。 5.1 Mathematical Description of the Uniform Rate Sampling Process So far, we have mainly talked about digital signals, that is, ordered numbers. However, many real systems characterize their performance by continuously varying processes over time. For example, the sound output of a stereo system represents a continuous change in sound pressure wave over time. The signal that changes in this way is called the analog signal. An example of an analog signal is shown in Figure 5-1.