论文编号:JD254 包括开题报告,任务书,设计图,仿真文件,外文翻译,一稿,二稿,定稿,正文字数:17199,页数:65 价格:200元
摘 要
测量以频率为参数的被测信号，通常采用的是测频法或测周法。但是，当频率变化较大，如范围为100Hz～100KHz时，测频法和测周法就存在着很大的局限性，难以实现宽频带、高精度的测量。所以，当要求有一种测频方法能对频率变化范围较大的信号进行高精度的测量时，就必须采用等精度的测频技术。
等精度频率计是一种能够高精度地测量被测信号频率的数字测量仪器。它被广泛应用于航天、航空、电子、测控、自动化测量等领域。本论文利用等精度频率测量的原理，达到设计等精度频率计的目的。由于Altera公司生产的复杂可编程逻辑（CPLD）EPM7128具有定时精确及速度快等特点；同时，因为涉及到的倒数运算（频率与周期互为倒数关系），在单片机AT89C51上运算会非常简单方便。所以，硬件方面主要由以上两部分组成。软件方面，用VHDL语言编程在MAX+PLUSII中完成CPLD的软件设计、编译、调试、仿真以及下载；其中，单片机AT89C51是系统的主控部件。
系统中，采用十进制数字显示，实现测量正弦信号，方波信号，尖脉冲信号的频率、周期等的基本功能， CPLD与单片机相互结合、取长补短，以达到最佳的效果。
关键词：等精度频率计 CPLD/FPGA VHDL 显示电路
Abstract
With regard to the parameters measured frequency signal，the commonly used method is measuring the frequency of weeks or measurement. However, when the frequency of large changes, such as the range of 100 Hz ~ 100KHz, measuring frequency and method of measurement on the week there is a lot of limitations, difficult to achieve wide-band, high-precision measurements. So, when requires a method of measuring frequency to frequency changes in the scope of the larger signal of the high-precision measurement, it must be used, such as precision of measuring frequency technology.
The accuracy of the same frequency is a high-precision measurement can be measured the number of signal frequency measuring instruments. It has been widely used in aerospace, aviation, electronics, monitoring and control, automated measurement, and other fields. In this paper, such as use of precision measuring frequency of the principle, to meet the design, and other precision frequency of Objective: Altera Corporation production due to the complex programmable logic (CPLD) EPM7128 with speed and precision timing, and other characteristics at the same time, because of the need to involve the countdown Computing (frequency and cycle countdown relationship to each other), and SCM AT89C51 numerical computing in a very easy and convenient. Therefore, the main hardware from the above two parts. Software, using VHDL language programming in MAX + PLUSII CPLD completed by the middle of the software design, build, debug, simulation and download; compilation of language used in the simulator-fu (wave), the entire circuit test signal control, data operations With the keyboard scanning and digital control of the simulation, including SCM AT89C51 is the main control system components.
System, using decimal figures show that the realization of measurement sine wave, square-wave signals, a sharp pulse of the frequency of the cycle, and other basic functions, CPLD and SCM integration, learning from, so as to achieve the best results.
Keywords：Equal precision frequency meters CPLD VHDL The show circuit
前 言
频率计在电子工程，资源勘探，仪器仪表等设备有条不紊地工作着，高效率地支配着系统的运行，是工程技术人员必不可少的测量工具。频率计最重要的功能是根据基准时钟信号实现对被测信号的频率进行检测。由此而延伸的频率测量是电子测量领域里的一项重要内容。因此频率计是工程技术工作者必须具有的测量工具，在此基础上的等精度频率计具有相当重要的意义。基于传统测频原理的频率计将随被测信号频率的下降而降低，在实用中有较大的局限性，而等精度频率计不但具有较高的测频精度，不随所测信号的变化而变化，而且在整个测频区域能保持恒定的测频精度。本课题利用EDA技术，基于CPLD芯片EPM7128设计来实现等精度频率计测量，这使设计过程大大简化，缩短了开发周期，减小了电路系统的体积，同时也有利于保证频率计具
