【正文】 。 虛擬儀器設(shè)計(jì)已經(jīng)成為測試與儀器技術(shù)發(fā)展的一個(gè)重要方向。在實(shí)際應(yīng)用中，記憶顯示功能主要用于測量信號的抖動情況或比較分析兩個(gè)以上的信號波形。 正常顯示、記憶顯示控制結(jié)構(gòu) 由雙功能邏輯驅(qū)動鍵 “正常 /記憶 ”控制，缺省為正常顯示。 主要控制結(jié)構(gòu) 測量控制結(jié)構(gòu) 通過邏輯按鍵 “測量 ”控制是否進(jìn)行測量；通過邏輯按鍵 “通道 ”控制通道選擇。主面板提供了兩個(gè)文件名輸入框，前一個(gè)為信號波形數(shù)據(jù)文件名輸入框，后一個(gè)為采樣周期文件名輸入框，這兩個(gè)文件由寫盤功能和讀盤功能共用。Display Unit 選擇，提供了 8 種單位。Windows 選擇，提供了 9 種頻譜 分析窗口； 頻譜分析模塊 頻譜分析模塊采用快速 FFT 算法，完成頻域信號分析。A ＋ B A－ B 模式：當(dāng)兩通道都處于選通狀態(tài)時(shí)，使用此模式來顯示兩通道信號代數(shù)相加、相減后的波形。A B A＆ B 模式：通過顯示通道選擇按鍵摚翑和摚聰，可以任意顯示某一通道或兩通道輸入信號的波形； 時(shí)基控制主要控制采集卡掃描率、每一通道掃描次數(shù)（取樣數(shù)）。觸發(fā)控制包括觸發(fā)模式、觸發(fā)斜坡、觸發(fā)電平控制； 系統(tǒng)軟件總體上包括數(shù)據(jù) 采集 、波形顯示、參數(shù)測量、頻譜分析及波形存儲和回放等五大模塊 . 數(shù)據(jù)采集模塊 數(shù)據(jù)采集模塊主要完成數(shù)據(jù)采集的控制，包括觸發(fā)控制、通道選擇控制、時(shí)基控制等?？傊?， LabVIEW 作為圖形化編程語言環(huán)境，為虛擬儀器開發(fā)提供了一種快捷、方便和功能強(qiáng)大的軟件工具。 LabVIEW 編程的另一個(gè)優(yōu)點(diǎn)是將軟件的界面設(shè)計(jì)與功能設(shè)計(jì)獨(dú)立開來，修改人機(jī)交互界面無需對整個(gè)程序進(jìn)行調(diào)試，這對設(shè)計(jì)像儀器 操作面板這樣復(fù)雜的人機(jī)界面而言是十分方便的。編程者可以通過交互式手段，采用圖形化框圖設(shè)計(jì)的方法，完成虛擬儀器的邏輯和測量分析功能設(shè)計(jì)。 除了由于經(jīng)費(fèi)原因使得所選數(shù)據(jù)采集卡采樣速率低于 HP54603B 外，本虛擬示波器在顯示、測量、分析、存儲和外部連接等方面的功能都不低于甚至高于 HP54603B ２ 軟件的設(shè)計(jì)與實(shí)現(xiàn) 軟件開發(fā)環(huán)境 虛擬數(shù)字示波器軟件設(shè)計(jì)采用了先進(jìn)的圖形化編程語言工具 LabVIEW for Windows98／ NT。本虛擬數(shù)字示波器還提供網(wǎng)絡(luò)接口，允許通過 TCP／ IP 協(xié)議實(shí)現(xiàn)網(wǎng)絡(luò)儀器共享或遠(yuǎn)程控制。 儀器功能 本虛擬數(shù)字示波器設(shè)計(jì)參考了 HP 公司的雙通道臺式數(shù)字存儲示波器 HP54603B 的功能，并在儀器分析和處理功能上有所擴(kuò)展。目前市場上采樣速率達(dá) 200MS／ s 的 PCI 數(shù)據(jù)采集卡已有成熟產(chǎn)品，技術(shù)上實(shí)現(xiàn)高帶寬的虛擬示波器不存在問題。這些功能使得我們不僅可以用該卡設(shè)計(jì)虛擬示波器，也可以設(shè)計(jì)虛擬 函數(shù)發(fā)生器或虛擬計(jì)數(shù)器，做到一卡多用。它支持單極和雙極性模擬信號輸入，信號輸入范圍分別為－ 5～＋ 5V 和 0～ 10V。 數(shù)據(jù)采集卡 PCI 總線傳輸速率高 數(shù)據(jù)吞吐量大 是今后數(shù)據(jù)采集板卡設(shè)計(jì)的主流。 １ 虛擬示波器的結(jié)構(gòu)與組成 本虛擬數(shù)字示波器主要由一塊 PCI 總線的多功能數(shù)據(jù)采集卡和相應(yīng)的軟件組成。數(shù)字示波器是在科學(xué)研究和工程設(shè)計(jì)中廣泛應(yīng)用的一種通 用儀器。因此，可以說虛擬儀器代表了未來測量儀器設(shè)計(jì)發(fā)展的方向。與傳統(tǒng)儀器相比，虛擬儀器除了在性能、易用性、用戶可定制性等方面具有更多優(yōu)點(diǎn)外，在工程應(yīng)用和社會經(jīng)濟(jì)效益方面也具有突出優(yōu)勢。從一般的儀器設(shè)計(jì)模型看，一種儀器無非是由數(shù)據(jù)采集、分析處理、人機(jī)交互和顯示等幾部分功能模塊組成的整體。所謂虛擬儀器，就是在通用的計(jì)算機(jī)平臺上定義和設(shè)計(jì)儀器的測試功能，使用者操作這臺計(jì)算機(jī)，就象是在使用一臺專門設(shè)計(jì)的電子儀器。虛擬儀器是９０年代提出的新概念。LabVIEW。 [關(guān)鍵詞 ] 虛擬儀器 。 re to improve its performance。 domain analysis functions。 through the logic key channel control channel selection. automatically adjust the scan rate of control structure By the logic of key group Automatic, manual to control the scan rate is automatically adjusted or manually adjust the scan rate. display, memory display control structure Logical drive from a dual function keys normal / memory control, the default for the normal show. In a normal state, can only show that A, B twochannel input signal waveform 2。 ? Log / Linear choice, provided the coordinates of two kinds of display mode。 ? XY mode: When the two channels are in a gated state, use this mode to display Lissajous (Lissajous) graphics, phase or frequency measurement。 ? Timebased control of the main control acquisition card scanning rate, each channel scanning frequency (sampling number). Waveform Display Module Software provides three types of waveform display modes: ? AB A amp。 the use of LabVIEW in the Call Library Function can call the standard dynamic link library (. DLL). In short, LabVIEW as a graphical programming language environment for the development of virtual instrument provides a fast, convenient and powerful software tools. The main function modules Generally speaking, virtual oscilloscope software control by the pletion of signal acquisition, processing and display. System software in general, including data acquisition, waveform display, parameter measurement, spectrum analysis and waveform storage and playback, such as the five modules. Data Acquisition Module Data acquisition module to plete the major data acquisition control, including trigger control, channel selection control, timebase control. Of which: ? trigger control, including the trigger mode, trigger slope, trigger level control。 on the other hand, the user can be some of the advanced digital signal processing algorithms used in the design of virtual instrument to provide the traditional desktop machines do not have the function, but also can be configured by software the realization of multifunctional integrated instrument design. Therefore, it can be said of virtual instrument measuring instruments on behalf of the future direction of design development. Virtual instrument technology is developing rapidly in foreign countries, the United States National Instruments (NI pany) to represent a group of vendors are already available in the market based on virtual instrument technology mercialization instruments designed products. Digital Oscilloscope in scientific research and engineering design of a widely used generalpurpose equipment. The following bination of a virtual digital oscilloscope design and development of virtual instrument details the basic position and based on the LabVIEW graphical programming language of the virtual instrument programming methods and technology. 1 Virtual Oscilloscope structure and position of The virtual digital oscilloscope PCI bus by a multifunction data acquisition card and the corresponding software. They are installed on a PC running the Windows95/98/NT machine (remended configuration in PENTIUM Ⅱ / 233 and above), which constitute a powerful digital oscilloscope can be stored. Data Acquisition Card PCI bus transfer rate of highdata throughput large future data acquisition board design mainstream. The design uses the PCI1200 data acquisition card is a better value for money products, support DMA mode and dualbuffer mode, ensuring the uninterrupted realtime signal acquisition and storage. It supports a unipolar and bipolar analog signal input, signal input in the range of 5 ~