【作者】 王战涛；

【导师】 朱瑞祥；

【作者基本信息】 西北农林科技大学 ， 农业机械化工程， 2008， 硕士

【摘要】 现代仪器正在向着智能化、便携式和虚拟化的方向发展。借助少许的采集硬件和通用PC平台,仪器正在由单一化向集成化、由物理仪器向虚拟仪器方向发展。虚拟仪器的发展必将推动现代仪器事业的发展。示波器是现代测试中必不可少的电子仪器。随着现代电子技术和通信技术的飞速进步,示波器的实现方式正在经历着深刻的变革。传统的模拟示波器由于结构和功能上存在的缺点,正在被功能强大、使用方便的数字示波器所取代。目前国产的测试用数字示波器在技术上还比较落后,高性能的数字示波器主要靠进口,进口数字示波器虽然功能强大,但价格太高,难以普及;另外,主流的数字示波器大都面向高频信号,高频DSP和数据采集芯片成本都很高,用于低频信号测试精度又难以满足要求。本设计针对示波器开发以上的两个方面的问题,尝试开发了一种低频虚拟数字示波器。该示波器除了具有传统模拟CRT示波器对波形的采集、显示等一般功能,还可以实现对波形数据的存储和打印,以及对波形参数的计算和显示。本设计的做要工作包括:1、分析了示波器的工作原理和虚拟示波器的结构,探讨了滤波器的实现技术,选择切比雪夫低通滤波器作为低通滤波模型,并运用Matlab软件设计了低通滤波器;2、选低成本单片机PIC16F877作为数据采集和处理单元,将采集到的脉冲转换成数字信号,通过RS232串口传送到PC;3、通过对数字存储示波器功能和结构的分析,运用Proteus绘制了示波器各个模块的模拟和数字电路,对各电路的组成进行了说明;4、对设计中涉及到的通信协议进行了阐述,结合硬件构架和协议开发,运用VC++进行了示波器系统软件的设计,最后运用信号发生器进行了示波器的仿真测试。仿真结果证明,设计的示波器能够对20KHz以内低频信号的获取和显示,满足普通测试要求。具有结构简洁、操作方便、成本低廉的特点,且易于进行功能的扩展,拥有广阔的应用前景。更多还原

【Abstract】 The osciloscope is an indispensible testing instrument. With rapid development in modern electronic and communication technilogy, its actualization technology is also experiencing a profound revolution. Due to its structural and functional defects, the conventional analog oscilloscope is now being replaced by the convenient digital storage oscilloscope. However, the domestic produced digital oscilloscope for testing is still technically backward, and the high-power digital oscilloscopes are mostly foreign produced. The imported digital oscilloscope is powerful but also expensive on the other hand, can not put into popular use. This study was targeted at solving the two problems mentioned above.In the designed virtual oscilloscope a low-cost PIC16F877 is selected as the unit for data acquisition and processing, which converted the collected analog signal to digital information and then transfered it to PC through RS232 serial port for storage or display. The stored signal can then be displayed on the screen of PC in wave form through a VC++ programed software interface in Windows. The designed oscilloscope has not only the functional of the conventional CRT oscilloscope like data collection and displaying, but also storage and display of the waveform data, as well as caculate and display the wave parameter.The methods adopted in this design and the conclusions are listed below:1. The working principle of oscilloscope and the structure of virtual sccilloscope are analyzed, and the actualization technology of filter is discussed. The Chebycov filter is selected as the low pass filter model, and the filter was designed using Matlab.2. By constructing the oscilloscope in a novel way of combining PICs and PC, it not only met the testing demand but also reduced the cost to a minimum.3. Based on the strutural and functional analysis of the digital oscilloscope, the analog and digital circuit of various modules of the oscilloscope is designed using Proteus, together with the introduction of the cirsuits. Circuit simulation indicated the designing is satisfactory.4. The communication protocols are explained, and software was designed using VC++, corresponded with the hardware and protocol development. And finally the simulation of the designing was conducted by using a signal generator. Conclusion:The simulation result indicated that the designed oscilloscope met the testing demand by successfully capturingand displaying the low frequency signal with 20Hz in wave form. The product has simple structure, easy manipulation and low building cost. The product has larg potential in functional extension and good prospect in popularity.更多还原