论文总字数：18055字

摘 要

弗兰克赫兹实验是大学物理的一项重要实验，在实验过程中需不断调节第二加速电压，测出相应的板极电流。

在目前市面上常见的弗兰克赫兹实验仪中，大多采用电位器来调节加速电压，实验过程中需要反复转动电位器，由于触点与电阻膜频繁摩擦，给电位器带来了严重机械磨损，从而出现电阻体和接触刷损坏，接触不良等情况。另一方面，电位器进行精准调节较为不便，难以准确得到期望电压，造成实验精度下降，实验误差增大。从而影响了实验教学的质量，为大学物理实验教学带来了诸多不便。针对这些情况，我们提出改进方案，提出数字控制方案，设计了全数字型弗兰克赫兹实验仪。

由于实验仪经常受外界因素例如磁场、雷电、温度等的干扰以及系统内部如高频信号、电路耦合、电压不稳，印刷电路板分布不合理等干扰，增加实验误差，为了得出较准确的实验结果必须进行抗干扰措施防护，探究抗干扰措施势在必行。本文从软件和硬件两个方面，阐述了我们对改进弗兰克赫兹实验仪所采用的抗干扰措施，包括电源设计，温度补偿，滤波，接地，屏蔽，布线，隔离和利用软件的指令冗余技术，软件陷阱，数字滤波，“看门狗”等设计。

关键词： 弗兰克赫兹 抗干扰措施 硬件 软件

ABSTRACT

Frank Hertz experiment is an important experiment of physics. During the experiment, it needs to adjust the second acceleration voltage constantly in order to measure the corresponding current plate. Most of the Frank Hertz experiment instrument in current market, the acceleration voltage is regulated by adjusting the potentiometer. During the experiment, it requires to rotate the potentiometer constantly. As the frequent friction exits between the contactor and the resistance film, serious mechanical wear will be brought to the potentiometer, which will lead to many problems such as the damage of resistance and contacting brush, poor contact and so on. On the other hand, the precise adjustment of the potentiometer is inconvenient, it is hard to obtain the desired voltage accurately and then the experimental accuracy will be influenced. It affects the quality of experimental teaching which brought a lot of inconvenience for the college physics experiment teaching. In response to these circumstances, we propose an improved scheme that designs an all-digital Frank Hertz experiment instrument.

Experiment instruments are often influenced by the external factors such as magnetic field, lightning, temperature and the system, such as high-frequency signals, circuit coupling, voltage instability, unreasonable distribution of printed circuit board interference. The experimental error will be increased with all of those factors. In order to obtain more accurate experimental results, it’s imperative to take anti-jamming measures. In this paper, we discuss the anti-jamming measures which used to improve the Frank Hertz experiment instruments from the aspects of software and hardware, Our discussion includes the design of power supply, temperature compensation, filtering, grounding, shielding, routing, isolation and the use of software instruction redundancy technology, software traps, digital filtering, "watchdog" and so on.

Key words: Frank Hertz ; anti-jamming measures ; hardware ; software

目录

摘要 I

ABSTRACT I

第一章 绪论 1

1.1 实验原理 1

1.2 设计背景 2

第二章 硬件抗干扰措施 5

2.1 电源 5

2.2 芯片 6

2.2.1 单片机 T89C58 6

2.2.2 D/A转换器 TLV5616 7

2.2.3模数转换器 ADS7816 9

2.2.4 运算放大器 LM358 12

2.3 滤波 14

2.4 接地技术 14

2.5屏蔽 15

2.6 布线工艺 15

2.7光耦隔离 16

第三章 软件抗干扰措施 18

3.1指令冗余 18

3.2设立软件陷阱 18

3.3 数字滤波 19

3.4 “看门狗”技术 25

第四章 设计总结 26

4.1 电路原理图及PCB图 26

4.2作品特点 30

4.3 总结 30

参考文献 32

致谢 35

第一章 绪论

1.1 实验原理

弗兰克-赫兹实验是大学物理的一项近代物理实验，是探索原子结构的重要途径之一。验证了原子发生跃变时吸收和发射的能量是分立的、不连续的，证明了原子能级的存在[2]。

波尔的原子理论：

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