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简易综合测试仪

论文编号:CK084 论文字数:14702,页数:41

摘要
测试仪器是科学仪器中重要的组成部分，随着科技的不断发展，对测试仪器的性能要求也是越来越高。而采用智能化数字仪器不仅能提高测量准确度，而且能提高电测量技术的自动化程度，从而提高计量检定人员的工作效率。
选频电平表是高灵敏度、高精密的电平测量仪表,它与电平振荡器配套可构成完整的传输测试设备,在电力系统中用于电力载波和电力线保护设备的电平、增益、衰减等特性的测试,以及高频保护收发讯机的测量调试。
选频电平表与电平振荡器随着微电子技术的发展而不断更新换代,采用国际先进的数字直接合成技术(DDS) 使频率稳定度达到了晶振的水平且技术性能显著提高,并使设备日益集成化、小型化、通用化。
本文主要介绍包含选频电平（电压）表和电平振荡器的简易综合测试仪以及具体设计, 选频电平（电压）表采用真有效值/ 直流转换芯片AD637把被测交流信号电压转换为与其有效值相等的直流电压，再经过A/D转换器采样后得到被测信号的电压有效值。电平振荡器采用直接数字频率合成芯片AD9851 进行频率合成，输出频率、增益可控的正弦波，并具有幅频特性测试和幅频特性数据存储回放功能。

关键词：选频电平表; 电平振荡器; DDS; 直接数字频率合成

Abstract
The test equipment is an important part of the scientific instrument. With the continuous development of science and technology, the test equipment is becoming more and more high performance requirements. Intelligent use of digital equipment will not only improve the measurement accuracy, but also improve the electrical measuring the degree of automation technology, and to improve verification efficiency of the workers.
Selected frequency level meter is high sensitivity, high level of precision measurement instruments, with the support of level oscillator constitute a complete transmission test equipment, in the power system for testing electricity power line carrier and the level of protective equipment, gain, Attenuation, and the measurement of debugging of the protection of high-frequency transceiver.
With the development of microelectronics technology Selected frequency level meter and the level oscillator continuously upgrade, and using international advanced digital direct synthesis (DDS) to achieve a frequency stability of the crystal and the level of technical performance significantly improved, and the Equipment will to the increasingly integrated, smaller and universal.
In this paper, contains Simple Comprehensive Test Instrument (Selected frequency level meter and the level oscillator) and its specific design, Selected frequency level meter used AC/DC converter chip AD637 measured the exchange of signals with the RMS voltage converter for the same DC voltage, then after A / D converter sample be tested ,to get the voltage signal RMS . Level oscillator using Direct Digital Synthesis chip AD9851 for Synthesis, output frequency, gain control of the sine wave and a frequency of testing and increase the frequency of data storage playback.

Key Words：Selected frequency level meter；Level oscillator；DDS；Direct Digital Synthesis

目录
摘要………………………………………………………………………………………………Ⅲ
Abstract…………………………………………………………………………………………Ⅳ
目录……………………………………………………………………………………………....Ⅴ
1 前言……………………………………………………………………………………………1
2 总体设计方案………………………………………………………………………………..2
2.1 系统总体结构…………………………………………………………………………..2
2.2 系统硬件结构…………………………………………………………………………..3
2.3 系统总体软件流程……………………………………………………………………..4
3 电压测量及要求…………………………………………………………………………...8
4 电平表与电平振荡器的设计方案选择………………………………………………...10
4.1 电平表的设计方案选择………………………………………………………………10
4.2 电平振荡器的设计方案选择…………………………………………………………10
5 电平表与电平振荡器的设计要点……………………………………………………..13
5.1 电平表设计要点………………………………………………………………………13
   5.2 AD9851 DDS集成芯片性能分析……………………………………………………14
     5.3 直接数字频率合成技术(DDS - Direct Digital Synthesis 17
    6 电平表的设计……………………………………………………………………………...21
6.1 电平表各模块设计……………………………………………………………………21
        7 电平振荡器的设计 24
7.1 合成频率值的控制……………………………………………………………………25
7.2 幅值控制………………………………………………………………………………25
7.3 使用继电器实现数控开关……………………………………………………………26
8 LCD显示设计 27
8.1 LCD显示电路设计……………………………………………………………….........27
8.2 LCD显示电路软件设计……………………………………………………….............28
9 抗干扰措施…………………………………………………………………………….......29
10 总结………………………………………………………………………………..............30
致谢……………………………………………………………………………………………...31
参考文献………………………………………………………………………………………..32
附录电路原理图………………………………………………………………………..........33

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