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摘要

采样定理在通信系统、信息传输理论方面占有十分重要的地位。采样过程是模拟信号数字化的第一步，采样性能的优劣关系到通信设备整个系统的性能指标。利用采样脉冲把一个连续信号变为离散时间样值的过程称为采样，采样后的信号称为脉冲调幅（PAM）信号。本论文研究和实现了可以用于通信原理实验，功能完备的PAM调制解调系统。

本论文针对实验室需求特点，系统地论述了PAM调制解调技术的现状、发展和电路的设计制作过程及应用，采用脉冲产生模块，函数信号发生模块，电源模块，PAM调制解调模块等四个模块开发简易多功能通信原理实验系统，除了实现采样定理实验外，还可以充当信号发生器提供实验中常用信号（如三角波，正弦波，方波，脉冲波），直流稳压电源等功能。

本设计所研究和开发的PAM调制解调系统电路，可为实验室相关实验的开设和后续研究提供实用的研究平台。

关键词：PAM，采样定理，信号发生器，稳压电源

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ABSTRACT

Sampling Theorem is very important both in theory of communication systems and information transmission. Sampling process is the first step of converting analog signals into digital signals and the performance of the sampling is related to performance of the communication equipments. Sampling is the process of using sampling pulse to turn a continuous signal into a discrete time signal, and the latter is called Pulse Amplitude Modulation (PAM) signal. This thesis studies and realizes a fully functional system--PAM modulator and demodulator, which can be used in communication principle labs.

The thesis is targeted at the needing features of laboratory, and describes the current situation and development of PAM technologies, the circuit design and application. It uses pulse generator module, function signal generator module, power module and PAM module to develop a simple experimental system with multiple functions. It can not only realize the sampling theorem experiment, but also act as a signal generator which can provide triangle wave, sine wave, square wave and pulse wave and a DC power supply, etc.

The PAM modulation and demodulation system, which is studied and developed by this thesis, provides a practical research platform for related laboratory experiments in the future.

Keywords: PAM, Sampling, Theorem, Signal Generator, Power Regulators

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目录

摘要 ................................................................................................................................ I ABSTRACT .................................................................................................................. II 第1章 绪论 ..................................................................................................................1

1.1背景 .................................................................................................................1

1.1.1 采样定理的现状和地位 ....................................................................1 1.1.2 信号产生技术状况 ............................................................................1 1.1.3 电源发展趋势 ....................................................................................2 1.2 课题主要研究内容和意义 ............................................................................2 第2章 PAM概述和原理.............................................................................................4

2.1 PAM原理........................................................................................................4

2.1.1 采样信号的时域分析 ........................................................................4 2.1.2 采样信号的频域分析 ........................................................................5 2.2 滤波器的原理 ................................................................................................6

2.2.1 设计要点 ............................................................................................7 2.2.2 滤波器的原理及论证 ........................................................................7 2.2.3 Sallen Key滤波器数学分析 ..............................................................8

第3章 PAM采样系统的实现...................................................................................10

3.1 PAM系统框图..............................................................................................10 3.2 电压保持电路 ..............................................................................................10

3.2.1 采样保持电路的原理 ......................................................................10 3.2.2 目前常用的采样保持芯片 ..............................................................12 3.2.3 对保持电容大小的分析 ..................................................................13 3.3 滤波器的MULTISIM仿真及分析 ............................................................14 3.4 PAM调制解调模块电路..............................................................................15 3.5 脉冲产生模块电路 ......................................................................................16 第4章 信号产生电路与电源的实现 ........................................................................17

4.1 信号发生器概述和原理 ..............................................................................17

4.1.1 相移法 ..............................................................................................17 4.1.2 文氏桥 ..............................................................................................18

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