基于混合信号的数据采集卡的虚拟示波器

基于混合信号的数据采集卡的虚拟示波器(中文4500字,英文2000字)
 摘要：
    复杂的信号在声纳系统、雷达系统、回声定位系统中有诸多应用并且用来学习和研究共振频率。数字存储示波器（DSO）现在被用于获取和显示常规信号。这台仪器普遍应用于各个测量实验室，虽然只有在显示简单的周期性波形如正弦波时有用，但是无法显示频率变化的复杂的信号。这个问题的出现是因为示波器的基本技术是用于触发波形，而对于复杂的信号像噪声等来说是不允许的。能真正解决这个问题的是混合信号示波器。这是一种成本较高的解决方法，然而一般的小型实验室承担不起这种昂贵的仪器。在本文中，建议选用成本合理的基于混合信号的数据采集卡的虚拟示波器来分析复杂的信号。一种智能技术，加权海明距离（WHD）算法用于准确地触发复杂波形，也被应用到了频谱分析（FDA）和时频分析（JTFA）技术。设计了一种基于LabVlEWTM具有功能扩展，能显示并且分析触发信号的虚拟仪器。集成化的编程语言选择LabVlEWTM是因为它提供了很多简单易用的功能。某种程度上提供了一种经济高效，快速灵活分析复杂的信号的方法。对于这种解决问题的方案的需求存在的原因是由于硬件系统的售价过于高昂。传统硬件系统先天不足。下面展示了一些虚拟示波器实际分析复杂信号的实时实验结果。
关键字：虚拟仪器，调频信号，数据采集，触发，复杂信号， JTFA。

A DAQ card based mixed signal virtual oscilloscope
Abstract
    Complex signals find many applications in SONAR, RADAR，Echo Location Systems and for studying the resonant frequencies. Digital Storage Oscilloscopcs(DSO) is used these days for acquisition and display of routine signals. This instrument, found in every measurement laboratory, though potent in displaying simple periodic waveforms like sinusoids fails when  frequency-varying time signals are applied, This problem surfaces because the underlying technique of oscilloscope used to trigger the waveform does not acquiesce with complex signals like chirp. Ready solution to this problem is the mixed signal oscilloscope. This is a costly solution and small laboratories cannot afford to have the costly instruments. In this paper, a cost effective DAQ card based mixed signal virtual 0scilloscope is proposed to study the complex signals. An intelligent technique, Weighted Hamming Distance (WHD) algorithm was used to accurately trigger the complex waveforms. Also for frequency domain analysis, Joint Time Frequency Analysis(JTFA) techniques were used. A LabVlEWTM based virtual instrument was designed and developed with a capability to acquire, display and analyze the triggered signal. The integrated programming language LabVIEWTM was chosen as it offers many simple ready to use functions. In a way the proposal offers a cost effective, fast and flexible solution to treat the complex signals. The need to create such solutions is the consequence of costly hardware systems. The deficiency of conventional hardware. Scheme for the virtual oscilloscope for complex signals with some real time experimental results are presented in this work.