2fsk调制与解调器的设计与实现毕业设计.doc

编号： 毕业设计说明书 题 目： 学　　院： 学院 专 业： 电子信息工程 姓 名： 学 号： 指导教师单位： 姓 名： 职 称： 题目类型： 理论研究 实验研究 工程设计 工程技术研究 软件开发 2015 年 5 月 20 日 摘 要 调制解调器在通信系统中的有着重要的地位，系统的性能很大程度上取决于它的好坏。二进制频率调制在数据通信的发展历史上，是一种较早使用的通信方式，这种调制解调方式的抗噪声干扰性能强大，抗衰落性能较强，实现起来有非常容易，由于这些优点，被广泛的应用于中低速数据传输系统中，所以一直以来都是学校数字信号调制教学的重点内容。但学生实验室中的2FSK调制与解调器采用整体电路的方式进行设计，电路板体积较大且灵活性较差。而此次毕业设计，按照各部分的不同，与解调中 关键词：2FSK；模块化；频移键控；压控振荡法；锁相解调；过零检测法 Abstract Modem has an important role in the communication system, the performance of the system is good or bad depends largely on it. Binary frequency modulation in the history of the development of data communications, is a means of communication used earlier, such a strong anti-noise modulation and demodulation performance, strong anti-fading performance, very easy to implement, because of these advantages, is widely used in low-speed data transmission system, it has been focused on digital signal modulation content of school teaching. However, the student lab 2FSK modulation and demodulation circuit device by way of the overall design, the circuit board larger and less flexible. And the graduation project, in accordance with the different functions of each part of the circuit, the 2FSK modulation and demodulation circuit modular system, each module design small modular circuit parameters different. About modulated signal, there are two commonly used methods, namely direct and indirect modulation modulation, in which the indirect modulation frequency shift keying method is used, the direct voltage controlled oscillator frequency modulation method is used. Demodulated overall signal can also be divided into two ways, coherent demodulation and non-coherent demodulation. In this graduation designs, non-coherent demodulation using zero-crossing detection method, coherent demodulation is using a phase-locked demodulation. Enables users to use, according to the needs, select the ap