信号与系统课程是电子信息类专业本科生必选的专业基础课程，也是以信息化、网络化、智能化为主要特征的新工科专业的核心课程。本课程主要讨论确定性信号的时域分析和变换域分析，线性时不变系统的描述与特性，以及信号通过线性时不变系统的时域分析与变换域分析，重点建立“信号表示”与“系统描述”的基本概念。简要介绍信号与系统的基本理论在轨道交通、通信系统和生物系统中的应用。选用教材为陈后金教授主编的国家级“十二五”规划教材《信号与系统》第3版，2020，高等教育出版社（图1）。
图1 信号与系统教材及其主要教学内容
北京交通大学信号与系统英文MOOC由国家级电工电子教学团队信号处理课程组教师精心打造，国家级教学名师陈后金教授领衔主讲。课程包括信号与系统分析导论、信号的时域分析、系统的时域分析、信号的频域分析、系统的频域分析、连续信号与系统的复频域分析、离散信号与系统的复频域分析、系统的状态变量分析八章内容，每个视频约10分钟左右，视频累计约800分钟。
北京交通大学信号与系统课程具有深厚积淀，课程教学效果得到师生普遍好评，课程建设成果得到同行专家的高度认可，获得了6项国家级课程称号（图2）。该课程2021年被评为首批国家级课程思政示范课程、2018年被评为首批国家精品在线开放课程（国家线上一流课程）、2012年被评为首批国家精品资源共享课程、2007被评为首批国家双语教学示范课程、2003被评为首批国家精品课程等。
图2 “信号与系统”获得的国家级课程称号
“信号与系统”课程已经开设50多年，一直沿袭最初的“信号变换、系统响应”的教学体系，其难以适应当今信息技术的发展。北京交通大学课程组扬弃了传统的信号与系统课程教学体系，建立了“信号表示、系统描述”的教学体系，其教学内涵更加清晰，更加适应新一代信息技术的发展和新工科专业建设（图3）。
图3 信号与系统课程的教学体系
课程的知识点围绕信号分析与系统分析两部分进行组织，准确地反映了“信号表示、系统描述”的教学体系，强调了知识点之间的内在联系和对应关系，有机地串联了课程的教学内容，让学生能够更好地把握住课程的主要脉络，构建了课程知识点图谱（图4）。
图4 课程知识点图谱
在教学内容更新上，提出知识没有“有用与无用”之分，但有“有用与更加有用”之别。根据课程教学内涵，剖析课程的教学重点与难点：为何介绍基本信号与基本运算？如何诠释信号的卷积与卷积和？为何要引入信号与系统的频域分析？如何介绍三大变换及其性质? 抽样定理的本质内容是什么？为何引入系统的复频域分析？等等。结合学科应用开展案例教学，将信号与系统课程的基本理论应用于生物神经网络、主体机车信号识别、音阶频谱分析等，拓展学生的视野，激发学生的学习兴趣。
1.1 Introduction to signals and sytems
1.2 Classification of signals
1.3 Classification of systems
Exercise
Chapter 2 Signal Analysis in the Time Domain
2.1 Elementary continuous-time signals
2.2 Basic operations on continuous-time signals
2.3 Elementary discrete-time signals
2.4 Basic operations on discrete-time signals
2.5 Signal decomposition
2.6 Tutorial
2.7 Signal analysis in time with MATLAB
Exercise
Chapter 3 System Analysis in the Time Domain
3.1 Description of linear time-invariant systems in the time domain
3.2 Response analysis of continuous-time LTI systems in the time domain
3.3 Response evaluation of continuous-time LTI systems
3.4 Impulse response for continuous-time LTI system characterization
3.5 Tutorial for response evaluation of continuous-time LTI systems
3.6 Response analysis of discrete-time LTI systems in the time domain
3.7 Response evaluation of discrete-time LTI systems
3.8 Impulse response of discrete-time LTI system characterization
3.9 Tutorial for response evaluation of discrete-time LTI systems
3.10 Analysis of systems in the time domain with MATLAB
Exercise
Midterm Exam: Chapters 1-3
Chapter 4 Signal Analysis in the Frequency Domain
4.1 Fourier analysis of periodic C-T signals
4.2 Frequency analysis of nonperiodic C-T signals
4.3 Fourier analysis of periodic D-T sequences
4.4 Fourier analysis of nonperiodic D-T sequences
4.5 Sampling of signals in the time domain
4.6 An example of signal analysis in the frequency domain
4.7 Frequency analysis of signals with MATLAB
Chapter 5 System Analysis in the Frequency Domain
5.1 Frequency response of a C-T LTI system
5.2 Evaluation of the frequency response of a C-T LTI systems
5.3 Zero-state response of a C-T LTI system to signals
5.4 Ideal analog filters
5.5 Frequency response of a D-T LTI system
5.6 Ideal digital filters
5.7 Amplitude modulation and demodulation
5.8 Frequency response analysis of systems in MATLAB
Midterm Exam: Chapters 4-5
Chapter 6 Complex Frequency Analysis of Continuous-Time Signals and Systems
6.1 C-T signal representation in the complex frequency domain
6.2 Unilateral Laplace transform of common C-T signals
6.3 Properties of unilateral Laplace transform
6.4 Evaluation of inverse Laplace transform
6.5 Bilateral Laplace transform and its inverse
6.6 Description of C-T LTI systems in the complex frequency domain
6.7 Transfer function and system properties
6.8 Implementation of C-T LTI systems
6.9 Complex frequency analysis of C-T LTI system response
6.10 Complex frequency analysis of signals and systems in MATLAB
Chapter 7 Complex Frequency Analysis of Discrete-Time Signals and Systems
7.1 Representation of D-T signals in z-domain
7.2 Unilateral z-transform of common D-T sequences
7.3 Properties of unilateral z-transform
7.4 Evaluation of unilateral z-transform
7.5 Bilateral z-transform and its inverse
7.6 Description of D-T LTI systems in z-domain
7.7 Transfer function and system properties
7.8 Implementation of D-T LTI systems
7.9 z-domain analysis of system's responses
7.10 Complex analysis of D-T signals and systems in MATLAB
Final Exam: Chapters 6-7