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1. 0 Vine oa m Disperse the wavelet funtion j y D yt k 17 WG k FOY 0 18 B Conformation of Wavelet Threshold Function As we know the power of noise is distributed in the whole wavelet domain 6 Whereas the power of useful signal concentrates in the big wavelet coeficient After wavelet decomposed the wavelet coeficient of useful signal is much bigger the noise So we can construct a threshold function to set the filtering threshold adaptively Then the useful signal can be resumed The threshold function oi as follows WT a T Wy xX eee Tied a Ixl F EA w x 0 1x lt Zl A 2log N o 19 When gt 9 w x bA A X xe 20 when lt 0 en x xe 21 108 American Journal of Engineering and Technology Research Vol 13 No 1 2013 Because the nonstationary signal includes break points the Fourier Transform can t confirm the break time and the variety which affects the whole spectrum graph of the signal However the wavelet change the resolve automaticly so it can distinguish the break points from noise A simulation in the MATLAB can prove it as figure 1 nonstation signal including noise 20r L L L L L L E L L E iu Mt yell a 10 ih Nya W Malauto oa lll hai y aul jin i pat nN W Hay ahata h M c i r r i r r r r r c 5 200 400 600 800 1000 1200 1400 1600 1800 2000 after Fourier analysis filtering 20r L L L L L L l L L r Ma 102. The application of wavelet analysis in ultrasonic sensor system characteristic signal pretreament Acta Scientiarun Naturaltitum Universitatis Nankaiensis Vol 38 No 2 pp 5 9 2005 6 Alexander Klein Tomas Sauer Andreas Jedynak and Wolfgang Skrandies Conventional and wavelet coherence applied to sensory evoked electrical brain activity IEEE Transactions on Biomedical Engineering Vol 53 No 2 pp 266 272 2006 7 Arnd Frech Amer Zakaria Stephan Braun and Peter Russer Ambient noise cancelation with a time domain EMI measurement system using adaptive filtering 2008 Asia Pacific Sympsoium on Electromagnetic Compatibility amp 19th International Zurich Symposium on Electromagnetic Compatibility 2008 pp 534 537 8 Huang Juan Qian Xin Wang Cheng Lin The construction of a wavelet filter and its application in environmental research Journal of Nanjing University Natural Sciences Vol 43 No 4 pp 389 396 2007 9 Liu Junwei and Tang Shiping Automatic test system for conducted susceptibility of low frequency based on LabVIEW Instrumentation technology No 1 pp 30 32 2007 10 M Bertocco C Offelli A Sona A virtual environment for EMC testing IEEE Intemational Workshop on Virmal and Intelligent Measurement Systems 2001 pp 18 21 11 National Instruments Corporation LabVIEW User Manual 2005 NI Ltd 115 American Journal of Engineering and Technology Research
3. guided missile environment so electromagnetic environment EME is extremely complicated Some equips were effected by electromagnetism energy in our practice Therefore this is an exigent and necessary mission of solving electromagnetic compatibility EMC problem The technology of EMC is not only a new and integrative subject domain but also a application of engineering scientific technology As T shinuzuka depicted in 1 the study of EMC technology and solving EMC problem base on a lot of test research and measure in practice We need to evaluate EMC of equip and find electromagnetic interference EMI problems by test The problem is presented detailed by B Sreedevi and N S Harischandra Rao in 2 With the electrical equipment and systems on the modern ship increasing quickly communication between the equipment is frequent At present most EMC testing is manual and the efficiency is poor so it becomes an urgent task that testing the EMC system fast and reliably Gong Fengxun and Ma Yangiu introducted a universal estimating and measurement method of EMI 3 By researching the EMC testing methods and EMC technique the paper designs a automatic testing system which can test save analyse and process data Because the testing signal include the ambient noise the wavelet analysis is applied to filter the noise and gain the real conducted electromagnetic interference Because of virtual instrument introduction the 105 American Journal
4. han A w T er F Ira f annn 0 kana Ny ae S k iid sin il ah Ad al i r r r t 0 200 400 600 800 1000 1200 1400 1600 1800 2000 after wavelet analysis filtering 20 E7 L L L L L L E e E l Nm LK rn BS OA wae oe pecs Oe bid oie malades i 0 lis A n ww stig 20 E r r r r r r r E 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Fig 1 Compared effect of filtering the noncalm signal between Fourier analysis and wavelet analysis From the third graph the signal processed by wavelet threshold function reserves the edge of useful signal To the opposite the Fourier analysis can t distinguish the edge of high frequency in useful signal from noise just as the second graph Testing Principle and System Hardware Structure Testing conducted emission is to make sure if there is radiofrequency current which affect other equipment s work through power supply line The current can be conducted to the shell by filter capacitor and interfere low frequency receiving equipment in the system Besides the system can test the noise in the power supply line The power is connected with line impedance stabilization network LISN and the current probe conducts the current value to the measurement receiver Then the data will be transmitted to the computer and analysed in the LabVIEW A Before Testing Calibrate the Testing Equipment 1 Impose 1 kHz 3 kHz and 10 kHz calibrating
5. Vol 13 No 1 2013 12 P Parhami M Marino S Watkins and E Nakauchi Innovative precompliance test methodology using ambient cancellation and coherence detection techniques IEEE International Symposium On Electromagnetic Compatibility 1999 pp 1022 1025 13 S Braun M Al Qedra and P Russer A novel realtime time domain measurement system based on field programmable gate arrays 17th International Zurich Symposium On Electromagnetic Compatibility 2006 pp 501 50 14 Shouxin Ren Ling Gao Application of a wavelet packet transform based radial basis function neural network to analyze overlapping spectral 2008 Congress on Image and Signal Processing 2008 pp 874 878 15 Surajit Midya and Rajeev Thottappillil An overview of electromagnetic compatibility challenges in European Rail Traffic Management System Transportation Research Part C 2007 pp 5 20 16 Wang Binggie Measurement of isolation between antennas mounted on aircraft IEEE 2007 International Symposium on Microwave Antenna Propagation and EMC Technologies For Wireless Communications 2007 pp 1311 1314 17 Weidong Zhang Xiang Cui Jie Zhao Xiaolin Li Qi Wang Zhibin Zhao Yuanyou Wang Measurement and analysis of electromagnetic disturbances in 500kV converter stations Proceedings 18th Int Zurich Symposium on EMC 2007 pp 249 252 18 Yu Jing Liao Rongtao Wen Dinge Design and implementation of a vi
6. American Journal of Engineering and Technology Research Vol 13 No 1 2013 AUTOMATIC TESTING SYSTEM FOR EMC TESTING WITH WAVELET ANALYSIS APPLICATION BADED ON LABVIEW Sheng Liu Lanyong Zhang Wugui Wang College of Automation Harbin Engineering University Harbin Heilongjiang China 150001 Zlyal hotmail com Abstract According to the problem that the speed of electromagnetic compatibility EMC manual system is slow a automatic testing system is designed for power supply line conducted emission based on general purpose interface bus GPIB and LabVIEW which actualizes a series of functions such as signal generating monitoring analyzing and showing It introduces the constituting of system testing principle software structure and solves the hard problems and key techniques such as hardware s controlling algorithm s fast convergence compatibility of software Because the testing signal include the ambient noise the wavelet analysis is applied to filter the noise and gain the real conducted electromagnetic interference Comparing with the other traditional apparatuses and the manual testing the system improves the test efficiency and has good extensibility Keywords Electromagnetic Interference LabVIEW Automatic Testing System Wavelet Analysis Introduction With the development in new technology of weapon the number and type of highly sophisticated electronics equipments and system fitted in the congested shipboard aircraft
7. g and Technology Research Vol 13 No 1 2013 3 Every curve should be 1 of the frequency resolution of the measurement receiver GPIB defines the address for every measuring instrument to be convenient for calling The computer keeps touch with every instrument through GPIB and analyse the data The hardware configuration of the testing system is as figure 3 Signal Generator oe ao i Current Bu Probe R upply Line t ESY p EUT LISN wz Current probe E Measurement Receiver Switch Control Unit LabVIEW Control Computer control Print report Fig 3 Testing system configuration Software Structure of System The virtual instrument system is constituted by hardware instrument and LabVIEW platform based on GPIB Compared with other development tools LabVIEW has special advantage such as graphical programming easily for understanding variety of function library and analyzing subroutine Besides it provides plenty of drivers for GPIB instrument Automatic testing program for testing is the core of the complete testing software which is an independent executable file EXE The EXE file can call the drivers of the instrument automatically to control the instrument At the same time it provides checking for dynamic link library DLL to make sure the DLL is right When user want to change the instrument program will control the instrument depend on the driver
8. o meets the user s requirement which is acquiring the report in short time This working mode avoids inputting data with hand and reduces the testing error so effectively improves the testing quality The LabVIEW will pick up the wavelet program files of MATLAB to process the signal The testing program of LabVIEW is as figure 7 112 American Journal of Engineering and Technology Research Login System Increase Frequency Begin Testing Pies Pig A x Fas Reset Parameters Fig 5 Software program flow Fig 6 Login interface 113 Vol 13 No 1 2013 American Journal of Engineering and Technology Research Vol 13 No 1 2013 since Fig 7 Testing program of LabVIEW D Result and Analysis Click testing button the system start to testing automatically The beeline in the figure is limit value of power supply line which GJBI51A regulates The curve is the practical testing value According to the figure power supply line conducted emission meets the regulation and there is some margin The printed result likes figure 8 Ni WW N NN GE Odiz Fig 8 Testing result and curve Conclusions The paper develops a automatic EMC testing system for electromagnetic interference based on LabVIEW platform which meets the standard of MIL The system comes from EMC automatic techniques developing and changes the bad present situation that the efficiency of manual
9. of Engineering and Technology Research Vol 13 No 1 2013 system has short development cycle and high operation efficiency There is an automated test system for EMC already in existence which is called TILE Totally Integrated Laboratory Environment System The paper designed the system which can also undergo digital signal processing with wavelet analysis application At the same time it has strong extensibility and repeatability which can reduce repeated investment The research results have important meanings on advancement of testing methods quality of EMC testing and improvement of EMC techniques The system has great value to popularize and application also achieve innovation achievements on hardware drivers based on LabVIEW Through reading and writing equipment drivers it can make the equipment collect analyse and save the signal At last the system will give a detailed report and a frequency graph Wavelet Analysis There are much lacalization in the nonstationary signal analysis with Fourier Transform due to its resolution which Charles K Chui studied The problem of the detection of a transient signal of unknown amplitude and arrival time which is buried in noise is not restricted to electromagnetic signal but is general to many practical situations The wavelet analysis is a powerful tool for nonstationary signal analysis because of the better resolution in frequency and time domain Since the nonstationary signal has complex f
10. operating is low It solves the problem that accuracy is poor The system combines hardware with software and the computer controls several instrument automatically and coordinated and the testing results can be real time showed The application of wavelet in the digital signal process improves the accuracy of the conducted testing The conducted interference testing has 114 American Journal of Engineering and Technology Research Vol 13 No 1 2013 high efficiency and precision The system running has proofed that automatic testing system for conducted emission improves the efficiency of testing work and reduces the work intensity References 1 T shinuzuka A Sugiura Reduction of ambient noise in EMI measurement IEEE International Symposium On Electromagnetic Compatibility Digest 1989 pp 24 28 2 B Sreedevi and N S Harischandra Rao Role of EMC in packaging of electronic warfare systems Proceedings of INCEMIC 2003 pp 132 136 3 Gong Fengxun Ma Yanqiu A universal estimating and measurement method of EMI IEEE 2007 International Symposium on Microwave Antenna Propagation and EMC Technologies For Wireless Communications 2007 pp 1239 1242 4 Hao Zhang T R Blackburn B T Phung and D Sen A novel wavelet transform technique for on line partial discharge measurements IEEE Transactions on Dielectrics and Electrical Insulation Vol 14 No 1 pp 3 14 2007 5 Yue Zhao Niu Wencheng
11. pplies probe and correction coefficient of measurement receiver Then increase the frequency and monitor output power and induced current and generate testing curve and testing report The program flow is as figure 5 C Set Up Virtual System Set the instrument address initial frequency last frequency and saving address for report before the experiment The standard limit value curve and scanning result of the receiver should be shown real time on the screen which can show if the testing result is higher than standard Build virtual platform of the whole testing system according to flow chart Then simulate every instrument Based on every virtual instrument integrate each module and create a virtual interface Because the testing engineering is flexible and large and the function of software increase quickly developing a convenient operation interface is essential for software perfect and user Different testing module have different interface and every interface includes login interface testing selecting interface parameter input interface data show interface and so on The login interface is as figure 6 The LabVIEW program will call the MATLAB file in the MATLAB scrip node to process the signal The wavelet analysis program is included in the MATLAB file Testing software program gives the testing report like frequency curve and printer prints the testing report and curve The method not only reduces testing personnel s work but als
12. requency component the wavelet transform can set different resolution for noise filtering Hao Zhang T R Blackburn B T Phung and D Sen used wavelet transform technique for On line Partial Discharge Measurements 4 Yue Zhao Niu Wencheng presented the application of wavelet analysis in ultrasonic sensor system characteristic signal pretreament 5 2 A Wavelet Transform For the function W x EL R the subspece Mi is genetated by Pee Just as follow V spanto k EZ jf EZ 1 In order to construct the model of wavelet analysis some definitions is given TT eat NV i eos Definition1 the space series Wine in the space LR 1 uniform monotone Y S o GM QV 0 2 gradual complety lt _ 72 rin UV I ER 3 expansion in rule f EV amp fRxeEV a JEZ meets the follow conditions clos 4 Riesz base exists there is 9 EV which makes that O k jeez is the Riesz base between limit A and limit B the base is as follow 9 2 j b 21 A2 x k 0 106 American Journal of Engineering and Technology Research Vol 13 No 1 2013 ViEZAG keZ g where is scale function 2 Then we call Multiple Resolution Analysis MRA in the space LR EV cV and 9 k EZ f generate one MRA because is a Riesz base in a then we get the relationship between scale functions in UP px gt P G2x k _ 3 Given that the wavelet meets the permission the wavelet in ican be generated as follow W
13. rtual instrument for electromagnetic field strength measurement The Eighth International Conference on Electronic Measurement and Instruments 2007 pp 395 398 116
14. s If system needs new instrument only one thing needs to do which is developing new instrument drivers A Set up Software Frame Setting up the whole software frame is important step for the testing system The software design for the automatic testing system for power supply line is modularity design and hierarchical design Designing the application use the Top Down design method At first analyse the whole requirements and performance parameter of the testing system Then divide the system into small function modules such as signal generating data reading and data analyzing The program structure not only increases maintainability of the program but also makes the flow chart clear It also avoids plenty of repeated programming and save much time There are many function modules in the LabVIEW function library The software structure is as figure 4 111 American Journal of Engineering and Technology Research Vol 13 No 1 2013 Automatic testing system SUIPRoY LRA SUIARS EWA JOWI eUSIS SuIsA euy geq woday N Fig 4 Testing system software structure The LabVIEW platform controls the hardware to generate signal collect data and analyse the data with variety of functions and driver programs Data disposal department is mainly to analyse signal and there is rich signal analyzing functions in the software platform B System Program Flow The system conducts communication to control instrument through GPIB and a
15. signal to current probe and the level of signal is 6dB lower than the limit value in GJBISIA 2 Use oscilloscope and load resistance to inspect current value and make sure if the current waveform is sine wave 109 American Journal of Engineering and Technology Research Vol 13 No 1 2013 3 Make the measurement receiver to scan in every frequency as scanning the common data then check whether the error current level between the value of data recorder and injection current level is in the range of 3dB 4 If it is larger or less than 3dB find the reason and correct it before testing Signal Generator 1 mt ieee D TTF EA Oscilloscope r A Measurement ct ae Receiver Tens Fig 1 Testing system calibration configuration B After Calibration Testing the Equipment EUT 1 Electrify the EUT and preheat it to make it work stably 2 Select one power supply line and fix current probe on it 3 Make the measurement receiver scan in the proper frequency according to GJB152A which regulates the least testing time and bandwidth 4 Test the other power supply lines in the method lt t 5cm Power Supply Line Curren Probe gt LISN JEE Measurement Receiver 6 3 Fig 2 Testing configuration C Data Provided 1 Draw the graph between amplitude and frequency automatically with X Y axis 2 Display proper limit value on the curve graph 110 American Journal of Engineerin
16. x gt q G 2x k _ 4 Yo generates a close subspace Wo as follow Function family Wa spantY kK EZ 5 Wi cV Therefore 1 from 2 and 5 When constructiong wavelet guarantee that us is the direct sum of Wo and Vo that 1s V V t Wo 6 Definition 2 W span y k E Z 7 from 2 and 7 W V W jez 8 2 Because V is a MRA of L R therefore R V OW DW 9 2 There is only solution for arbitrary J ELR FOFO Og a aH 10 Where LEY BOE Ji gt I POTER is the detail component in different resolution In the actual system because the resolution of testing equipment is limited we hold that the information FOAK N eV from 10 JOCK 1 fLl 1 8 CK D P g x K 1 g x K 1 A Prt x gt gt PKW 4 x keZ jel k2z 11 is the approximition in low frequency of 107 American Journal of Engineering and Technology Research Vol 13 No 1 2013 when using the orthogonal wavelet diz F Puk Cj x FV 6 12 2 Equation 11 1s the MRA wavelet model of the signal J ELR Just as follow f x D gt Wipes x ik 13 Wavelet transform is as follows x t a gt O vl 14 Where PO is basic wavelet function is scale When changing the lower the frequency is the lower the time resolution is so as the opposite The Morlet wavelet has fast computation speed and can process data online so we choose the Morlet wavelet A pie w t e 15
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