Applying of the DSP Technology in the Virtual Instrument System

The hardware architecture and instruction set of the digital signal processor leads to its high speed and precision in processing data. Aiming at the virtual instrument's deficiency in speed and precision resulting from the limit of the computers' development, the author brings forward a method to promote the performance of the virtual instruments using the DSP technology. Implementing the complex algorithms in DSP and using the principal and subordinate DSP structure or DMA technology in the data acquisition card of the virtual instrument can promote the virtual instrument's real-time characteristic greatly. Several key technologies are introduced in realizing the data acquisition and processing card. The experiment shows that the digital signal processors have higher speed and precision than the computers when implementing complex algorithms, and that using the DSP to implement the algorithms is an effective method to promote the virtual instrument's performance.     

PCI Bus Card and Its Applications in the Virtual Instrument

This paper analyses the PCI bus features, and introduces several developing tolls and the techniques, including PCI controller IC, driver development software and the key points of designing PCI cards with the main focus on IC S5933 and driver development software WinDriver. An example in the virtual instrument-a random signal generator, consisting of PCI card and software, is also given. DDS is realized by software, through the high transfer speed of PCI bus. The signal generator can produce sin, noise, frequency sweep and others complex waves. It can be used to adjust the wave, frequency, amplitude, phase and precision conveniently and accurately.     

Development of Data Acquisition and Processing System Based on DSP and USB 2.0

The data acquisition and processing system are proceeding towards faster, more powerful, easier to use and more cost effectiveness. This paper discuss the design of the high speed and convenient data acquisition and processing system based on DSP and USB 2.0, and expatiates the principle and method of the virtual instruments system in detail. The system employs an ADS8346 to sample the six channel signals simultaneously with a resolution of 16-bit.It utilizes EZ-USB FX2 as the USB2.0 interface, which can achieve the high speed communication between the host and the system. It uses TMS320VC33 (dsp) as the core chip, which can accomplish the function of the main control and real-time digital signal processing. The system enhances the virtual instruments' advantage more by the combination between software and hardware.     

PDA Based Virtual Instrument

Test and Measurement task can be done without limit of time and space by PDA with virtual instrument technology. The structure of PDA based virtual instrument is described firstly. Then PMDS(PDA Measurement Develop System) which can construct virtual instruments efficiently using component technology is introduced, it can enhance quality and efficiency of instruments. Finally, portable spectrum analyzer and mobile temperature monitor is built with PMDS to illuminate the usage of PMDS.     

Error Description and Modification of Virtual Measuring Instrument

When measuring, virtual instruments are inevitable to cause error damaging the precision of measuring resuits. It presents error constitution, methods of error transfer and synthesis of virtual measuring instrument. Based on the analysis of error transfer and synthesis of virtual measuring tual measuring instrument and gets the method of dealing instrument, it generalizes the error constitution formula of virwith errors. Then, errors can be modifyed.     

Frequency Refining Analysis and Its Applications in the VIs

Frequency refining is an important spectrum analyzing tool, and is one of the main function of signal processing and the virtual instrument. This paper introduces several typical frequency refining analysis methods including DFT and multiple modulation and so on. It also probes into their advantages and disadvantages, and proposes a new frequency refining method combining subband decomposing DFT and multiple modulation, which inherits the advantages of multiple modulation, needs not to design a specific filter, reduces the amount of calculation, and is fit for real-time refining analysis. At last, it exhibits several frequency refining algorithm and their effects with applications in virtual instruments.     

A Virtual Wavelet Transform Analyzer for the Signal Analysis Based on the Direct Algorithm

A virtual wavelet transform analyzer for the signal analysis based on the direct algorithm is introduced so that the discrete wavelet transform and continuous wavelet transform is maken to signal in the direct algorithm. The authors first introduce the direct algorithm of the WT, which is numerical algorithm obtained from the original formula of the wavelet transform by directly numericalizing. Then some conclusions are drawn on the direct algorithm. The examples are the sampling principle and technology for the wavelets, the limitation of the scale range of the wavelets and the measures to solve the edge phenomenal in the direct algorithm of the discrete wavelet transform, and some conclusions in the direct algorithm of the continuous wavelet transform. The virtual wavelet transform analyzer for the signal analysis based on the direct algorithm explored based on these studies and combined with virtual instrument technique can make the discrete wavelet transform and continuous wavelet transform to signal with any basic wavelet. It can be applied in studying the property of any basic wavelet and learning the theory on the wavelet transform, and also in making some engineering signal analysis. In the end, the authors give some typical examples for the application of the virtual analyzer. These examples show that the analyzer can be applied in many situations.     

Error Analysis and Modification of Virtual Instrument System

The errors of each parts of virtual instrument system, which are produced in the signals transfer process, are introduced. These errors include sensor error, signal conditioning error, data acquisition error and data dealing error, etc. The main error can be found by analyzing the influence of these errors on different virtual instrument system. The methods of errors modification are also discussed. It's an effective method that modifying system errors, especially nonlinear errors, by software. At last, as a good example, the error analysis and modification of Virtual Noise Analysis Instrument is given.     

Detecting System of the Dielectric Loss in Capacitive Equipment Based on Virtual Instruments

A digital detecting system of the dielectric loss in the capacitive equipment is introduced based on virtual instruments.This system can real-time collect,analyze,process and storage electrical signals with National Instruments' program LabVIEW and ADLINK,s DAQ board.Through the simulation test in lab and the real test in electric substation,it is shown that this system has high accuracy on testing the dielectric loss in the capacitive equipment,the real test data is stable and the relative error of real dielectric loss is less than 5%.It is to say that this system can meet the requirement of the real on-line monitoring.     

Analysis on the Effect of Harmonic on the Instruments with Average Value Principle

The application of non-linear load produces a mass of harmonics. The AC voltage meter and the AC current meter used in power system are usually rectifying instruments, which adopt principle of responding to the average value of voltage and current and get the virtual value by using of the proportion between the average value and it. Because they are designed based on the 50 Hz standard sinuous wave, the principle error will occur when the voltageof power system and the current of loads include harmonic. Based on their working principle, this kind of error is analyzed quantificationally. And the result shows that it can not be neglected. The voltage and current meters with real virtual value are proposed.     

Application on Extracting Feature in State Monitoring and Fault Diagnosis

With the development and application of information and internet and virtual instrument technology ,the virtual globular company based on internet arises .To study remote state monitoring, remote fault detection and diagnosis about large scale, complicated and integrative equipment become very important. In the whole fault diagnosis system , the detecting ,data acquisition is original ,processing; transform and extracting features with the signal detected is a key factor. The theories and methods used in mechanical fault diagnosis is stated. The application of signal process and its feature extracting methods is introduced which are time domain, frequency domain and time frequency domain analysis, in state monitoring and fault diagnosis with its signal analysis. The processing method of random time variant special signal is given also.     

Some Discussion On the Calculation of the Discrete Fourier Transform(DFT)

In the field of signal analyies for time frequency, the DFT is a familiar term. Especially,when its efficient algorithm FFT given, the other operations in signal analyses are also usually translated to DFT as soon as possible so as to enhance the calculating speed. But in our exploning the virtual instrument for time frequency analyzing, two sorts of formulas to calculate DFT and its inverse transform (IDFT) are found. These results are in different value of operation from different signal analysts or from different instruments for time frequency analyzing, their physical meaning are also not clear enough.The period extent theory some previous document based on when defined DFT is firstly expatiated. Then, separately with future defining coefficient method and analogy evolvement method, the authors argue that, based on the period extent theory, it is more rational to calculate DFT with the formula given. A shortage is pointed out and corrected is appeared in some previous documents when having given the formula of DFT. The improper view is also clarified that the reason why there are two sorts of formulas is make by custom.The rationality of the authors view with three examples is visually verified in the end.     

Modular Developing of Intelligent Controls-oriented Virtual Instrumentt

The concepts and principles of intelligent virtual controls(IVC) and virtual instruments based on them are introduced.The quintuple systematic model based on computer is discussed.By deep researching into the intelligent controls-oriented virtual instrument(ICVI) and its development system,the quintuple systematic model based on computer is introduced into ICVI systems,the uniform model of ICVI is built up and dissertated it in detail.The model builds uniform rules and methods for developing and using ICVI,and normalizes the development of ICVI.     

Sampling Technique of ECG Signal in Windows98

A method of real time sampling and data processing of ECG signal in Windows98 is introduced in this article. It makes the data collecting and processing easy by driving the A/D transforming card with the Vxd programmed with VtoolsD and VC++, drawing the curve of ECG on memory DC, and utilizing the virtual memory technique to realize the data storing.     

Research on IN/Internet Interworking Based on Virtual Switch

A scheme of virtual switch based on the idea of softswitch is proposed to realize IN/Internet interworking,after analyzing the interface of IN/Internet interworking.Then the logic entities,signal functions,construction frame and services characteristics of virtual switch are presented in detail.Moreover as cited examples,virtual SSP and virtual SCP are constructed by virtual switch to realize IN/Internt interworking.     

Research and Development of the Network Virtual Instrument

This paper introduces a basic concept of network virtual instrument and presents a solving scheme based on the .net framework for web network virtual instrument in which the component technology are used to construct UI component, data-service component, signal-processing component, DB-component, controlling component and data-acquiring component, in accordance to demand these component above can be flexibly put on the right place to realize remote test and control. In the light of the scheme, a set of network oscilloscope based on web is designed to remotely sampling data, and the technology of data base is successfully used to administer the saving and taking of signals in network virtual instrument .     

The Signals Analysis System Based on Fast Wavelet Transform

The fast wavelet transform (FWT) algorithm in wavelet analysis was introduced in the paper. With quadrature mirror filters (QMF) associated with popular wavelet bases, the fast wavelet decomposition and reconstruction for signals were implemented. Combined with virtual instrument technique, the FWT analysis system for signals was successfully developed. The system can break up signal not only into approximations, which are the high-scale and low-frequency components of the signal, but also into details which are the low-scale and high-frequency components. Especially it can identify singularity signal, which contain some important message of equipment condition and fault, and refine signal from noisy signal, which is corrupted by noise.     

ADSL Self-adapting detecting Method Based on DSP

Asymmetrical Digital Subscriber Loop (ADSL) is suitable to eliminate "the last mile" bottleneck of current broadband solutions, which use the existing telephone network and apply more and more abroad. It results in the higher demands of the detecting equipment. According to the review and comparison of today "s ADSL detect instruments, a new method is put forward with the system design, which self - adapting detecting can be used to test the ADSLs transmission characters on the whole band dynamically. Current DSP is used to operate arithmetic. The self - adapting detecting arithmetic can get the characteristic of signal channel through the MATLAB simulation.     

农业大棚温度自动记录仪设计

为了便于实时监控农业大棚温度的变化,设计了测定农业大棚小环境的温度自动记录仪。该记录仪采用数字温度传感器、单片机、显示器和I2C器件。软件设计主要包括：温度信号的采集、温度数据的储存与读取、汉字与采集结果的混合显示3个模块;通过对系统的设计进行Proteus仿真,结果表明系统的软硬件设计正确。