Design And Implementation Of Virtual Digital-Storage Oscilloscope

The virtual instrument technology is a new technology which developed in 90's of the 20th century. Its core thought is "The software is the instrument". It combines the computer hardware with the instrument hardware through the software, and utilizes the PC's strong data processing ability, operates the computer according to the interface that the software defined, completes a series of function of the signal collecting, analyzing, processing, judging and display, and realizes the function of the instrument in the end. The emergence of the virtual instrument symbolizes the automatic measure technology and the electronic measure instrument technology has entered into a new developing era. With the development of science and technology, the virtual instrument will become the instrumental and inevitable trend of future.The virtual digital-storage oscilloscope is a kind of typical virtual instrument. It has basic characteristic of the virtual instrument. This article introduces the exploitation and the principle of a kind of 40Msps's virtual digital-storage oscilloscope.At first, the article introduces the virtual instrument and its related contents, discusses the concept and characteristics, the present conditionses and the developing trend, constituting and principle, compare with the traditional instrument of the virtual instrument. The article describes the project of the system by the introduction of the system structure, the design goal, the significance and purpose of the research. This part of article analyzes the related information, explains the foundation and meaning of the project.Then, the article introduces the design of the hardware of the virtual instrument completely and systematically from the structure of the system. In this part, some important chips are mentioned at first. Analyzing the principle of each circuit unit of the virtual digital-storage oscilloscope is the main content of this part. Among these unit circuits, the DMA circuit, the system control circuit, the channel control circuitand the trigger control circuit are important unit circuits of this system. The key of hardware electric circuit is the DMA. Due to the sampling frequency of this virtual digital-storage oscilloscope is as high as 40Msps, the single-chip processor can't be able to control the A/D converter directly to sampling in high speed and read or write the memory in high speed. We must design a specialized electric circuit of DMA to complete this task. In the end of this part, the design of the control-software of hardware circuit is still presented.The thought of "The software is the instrument" expressed the position and the function of the software in virtual instrument. The main function of the virtual instrument is defined and implemented by the software. In this system, the measure-and-control software is the core of the virtual digital-storage oscilloscope. This article presents detailedly the design thought and the implementation dethod of the measure-and-control software of the virtual digital-storage oscilloscope from the summary, the interface and the function design, the software structure and the key technique and the design method. Among them, the key technique and the design method, especially the principle and the application of the MSComm controls and the OnComm procedure of the MSComm controls are discussed and analysed thoroughly.Finally, the paper evaluates and summarizes the result of the project, discusses the advanced feature, the practicability, the maneuverability, the upgrade characteristic and the data authenticity and reliability of the system, and introduces the result of the application of this project, and also introduces the contents of further researches and improvements conceive.