摘 要：为了对信号频率的测量的精准和还有其他参数的准确性,采用了一种以核心为STC89C51的单片机,预处理电路由三部分构成:一个施密特触发器74HC14,一个分度装置74HC4040还有三极管3DG120,设计出一种可以对信号的频率、脉宽、周期、占空比等参数的测量的频率计,该频率计测量的数据通过串口上传到主机,然后逐级做出相应的处理并且把测量信号的测量数据的值和参数在显示屏显示出来,还能描述测量信号的波形,得到硬件模块电路和软件的设计找到相应的可以防止小信号干扰的方法,这次试验的系统结构简单还要体现数字频率计的多功能性,并且测量的误差要控制在小于等于0。1%的范围,频率要求在1Hz—50MHz的各类信号,并且要求可以测量小信号,幅值小于0。5mV的信号。82840

毕业论文关键词：频率计；多参数测量；多功能；单片机；小信号

Design of Multi Function Digital Frequency Meter

Abstract: In order to measure the accuracy of signal frequency accuracy and other parameters, using a STC89C51 microcontroller core, pretreatment circuit consists of three parts: a Schmidt trigger 74HC14, a triode 3DG120 and 74HC4040 indexing device, design a kind of signal frequency, pulse width, period, the parameters of the measurement of the frequency ratio, the frequency measurement data to the host computer via the serial upload, then gradually make corresponding processing and the measurement data of measuring signal values and parameters in the display, but also describes the measurement signal waveform, get the design of hardware circuit and software method can find prevent small signal interference and corresponding multi functional structure of the test system also reflects the simple digital frequency meter, and the measurement error should be controlled in less than or equal to 0 1% range, frequency requirements in 50MHz - 1Hz of all kinds of signals, and the requirements can be measured small signal amplitude is less than 0。5mV of the signal。

Key Words: Frequency meter; Multi parameter measurement; Multi function; Single chip microcomputer; Small signal

目  录

摘要 1

1。综述本课题研究动态，说明选题的依据和意义 2

1。1课题研究的价值和意义 2

1。2发展状况 2

1。3数字频率计的种类 2

2。数字频率计总体设计方案 3

2。1设计任务与要求 3

2。2数字频率计结构设计思路 3

2。3基本设计原理 4

3。硬件设计 4

3。1硬件部分设计 4

3。2信号预处理电路 5

3。3分频电路 7

3。4测量数据显示电路 7

4。软件设计 9

5。系统测试及分析及仿真 11

5。1信号测试结果 11

5。2仿真 11

5。3实验分析 13

6。结束语 14

6。1总结 14

6。2系统的改善 14

参考文献 14

致谢 16

多功能数字频率计的设计1。 综述本课题研究动态，说明选题的依据和意义