说明：  《信号与系统》是高等教育出版社出版的普通高等教育“九五” 国家级重点教材，编者为清华大学电子工程系教授郑君里。《信号与系统(下)》的主要内容包括离散系统的时域分析、Z变换、离散傅里叶变换、模拟与数字滤波器、反馈系统、状态变量分析等。
(Signals and systems is a national key textbook for general higher education published by higher education press, edited by Zheng Junli, Professor of Electronic Engineering Department of Tsinghua University. The main contents of signal and system (2) include discrete system time domain analysis, Z transform, discrete Fourier transform, analog and digital filter, feedback system, state variable analysis and so on.)