锁相放大器原理和模块实现与仿真

本 科 生 毕 业 论 文(设计)

题 目 数字锁相放大器的设计

姓名与学号 胡和益 3070801222

指导教师 马慧莲

年级与专业 2007电子科学与技术

信息与电子工程学系

摘要

微弱数字信号检测技术，在科学技术发展中起到越来越重要的作用，其中数字锁相放大器更是受到广泛的研究。本文在介绍数字锁相放大器及CORDIC算法基本原理的基础上，根据谐振式光纤陀螺数字信号检测电路实际现状，用SIMULINK工具搭建锁相放大器的各个模块，用CORDIC算法实现载波的产生以及解调过程，并通过移相实现同步解调。解调信号用数字低通滤波器进行滤波后得到待测信号的幅度值，由此获取陀螺的转动信号值。本文对整个锁相放大器系统的各个模块进行仿真和分析，得到系统的解调范围与解调精度。并通过对现有系统的改进，在解调前加入带通滤波器，改善解调后低通滤波器的性能等，以提高系统的解调精度。本文的仿真结果可用于指导实际实验中算法的改进，参数的选择以及方案的修改等，提高实际系统的检测精度。

关键词：数字锁相放大器 CORDIC算法 同步解调SIMULINK

Abstract

The technology of weak signal dection plays a more and more important role in the development of science and technology. Among them, the research of Lock In Amplifier has drawn great attention. This thesis which is based on the introduction of Lock in Amplifier and the basic principle of CORDIC, builds the module of Lock in Amplifier by using SIMULINK, realizes carrier generation and process of demodulation by using CORDIC, and reach the aim of synchronous demodulation by phase-shift. After using the digital low-pass filter, though the demodulation signal，we will obtain the magtitude of signal that needs to be measured, thus acquires the value of gyroscopic's rotating-signal .In this paper, the range and precision of the demodulation are given through the simulation and analysis of Lock In Amplifier. Through the improvement of existing system, adding the band pass filter before demodulation and improving the performance of low-pass filter, we can improve the demodulation precision of system. The simulation of this paper can be used for the improvement of algorithm , the selection of parameter and the modification of project to improve the detecting precision of actual systems.

Keywords: Digital Lock In Amplifier, CORDIC, synchronous demodulation, SIMULINK

目录

第一章 引言1

1.1背景1

1.2国内外研究成果与现状2

1.3本文的主要内容3

第二章 锁相放大器原理和模块实现与仿真4

2.1锁相放大器的基本原理4

2.2 各系统模块实现与仿真6

2.2.1 ADC模块6

2.2.2 DAC建模和仿真8

2.2.3 ADC和DAC模块联合仿真9

2.2.4 低通滤波器模块10

2.2.5 正弦波产生模块13

2.2.6