Abstract This paper is about Simulink QAM modulation and demodulation implementation. Firstly, the basic principle of QAM modulation and demodulation system is introduced. Then, the basic operation of system modeling and simulation under simulation software Simulink is introduced. The emphasis is on modeling and simulation of 16QAM system modules, and 16QAM modulation and demodulation are realized. Finally, a 2DPSK system simulation is carried out to compare it with the 16QAM system. It is concluded that 16QAM is a relatively superior modulation and demodulation system.

Abstract Online examination system is a collection of modern test theory, methods and modern information technology mean intelligent online examination system, make full use of the school's existing computer software and hardware resources and network resources to achieve paperless examination to make up for the lack of traditional manual examination. I mainly develop the system of the background management subsystem, which includes the trial management, test questions, online volume, and test paper management, arrange exams, check the exam rankings, and check the test scores and other functions.This paper describes the development process of online examination system, using B-S mode, using SSH (Struts+Spring+Hibernate) framework, JavaScript, Servlet, Ajax and other major technologies, the use of Oracle database, MyEclipse development tools. This paper mainly introduces the development process of an online examination system, including requirements analysis, data flow analysis, functional design, database design, system implementation, system debugging and testing.