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Table of Content

15 July 2011 Volume 24 Issue 7
  
    Articles
    A Hand Prosthesis Control System Based on EEG and Surface EMG
    LV Jun
    . 2011, 24(7):  1. 
    Abstract ( 982 )   PDF (636KB) ( 833 )  
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    The paper proposes a hand prosthesis control system which integrates the information of the electroencephalograph (EEG) and surface electromyography (SMG) signals.This system can decode the hand movement velocity,acceleration and trajectory in real time and realize the flexible control of hand prosthesis.Moreover,this system does not need planting invasive electrodes and is convenient for maintenance.

    Design and Simulation of a Bandgap Reference Circuit
    LI Yong-Feng, HUANG Juan, WANG Dan, WANG Long-Ye
    . 2011, 24(7):  3. 
    Abstract ( 1701 )   PDF (399KB) ( 1118 )  
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    By using 0.18 μm complementary metal oxide semiconductor (CMOS) model,a bandgap reference circuit is designed.The circuit is simulated by Hspice.When operating at a 5 V power supply with the temperature range from -25 to 80 ℃,the device has a temperature coefficient of 9.14×10-6 ℃.It outputs a voltage of 1 250±43 mV at room temperature,when the power supply varies from 3 V to 5 V.

    A New Method for Repressing DDS Spur Based on Second-order Phase Dithering
    WANG Feng, LI Cheng, YANG Xiao-Yong
    . 2011, 24(7):  6. 
    Abstract ( 2002 )   PDF (550KB) ( 812 )  
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    Direct digital frequency synthesis (DDS) spurious suppression is one of the focuses of current research,in which the phase dithering is a common method of inhibiting phase truncation spurs.This article first introduces the basic principles of DDS and spurious sources,and then analyzes the phase truncation spurious reason and the principles of general phase dithering,and presents an improved method based on second-order phase dithering.A rigorous derivation and proof of the method is made.The study shows that the repressing effect of DDS spur using this method is more significant than the ordinary phase dithering method,which can reach 18 dB per phase bits.Finally,the feasibility of the method is verified using MATLAB simulation of the DSP Builder.

    DC Bias Technology Based on Digital Potentiometers
    ZHANG Guo-Chen
    . 2011, 24(7):  10. 
    Abstract ( 1491 )   PDF (849KB) ( 1026 )  
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    This paper mainly discusses the DC bias technology based on digital potentiometers.A theoretical analysis is made of the influence of noise on DC bias,with focus on the key technique for realizing DC bias using the microcontroller and digital potentiometers.Simulation analysis shows that this technique has low noise,flexible adjustment and high precision.In practical application,it is reliable and stable,and meeting the technical working requirements.

    Modified Vivaldi Antenna
    LI He-Yan, LI Ping, JIANG Xu-Dong
    . 2011, 24(7):  15. 
    Abstract ( 1648 )   PDF (608KB) ( 936 )  
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    For great back-radiation and low gain in the main-direction of traditional vivaldi antenna,the article proposes a method for the improvement and optimization of antenna structure by adding slots on the metal patch.By this method,the current can be forced to gather up along the taper-slot to improve the antenna radiation property.The gain of 350 MHz is 5.7 dBi while the gain of 830 MHz is 8.7 dBi.Vivaldi antenna is measured by Network Analyzer.The impedance bandwidth of measured data is covered from 310 to 1 300 MHz,which is consistent with the simulated data.

    Design and Simulation of 16-Channel Didgital Alarm Based on 74148
    WU Yong-Ling, YANG Yu
    . 2011, 24(7):  18. 
    Abstract ( 1646 )   PDF (790KB) ( 947 )  
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    This paper presents a scale of integrated circuits in both the main priority encoder 74148,7447,and the door with the small and medium-scale integrated circuits and other devices to trigger alarms with the break instead of pyroelectric infrared sensors.A functional and practical low cost voice alarm and digital display as one of the anti-theft alarm is designed.By the application of simulation software EWB5.0,the design realizes priority alarm,multi-channel digital display and other functions to meet the needs of ordinary users.The design is of value in the production of alarms of low-cost,multi dispatched points and prevention priority.

    Reactive Power Compensation under Strong Harmonic
    WANG Feng, QIANG Shun-Yi
    . 2011, 24(7):  21. 
    Abstract ( 1353 )   PDF (731KB) ( 878 )  
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    The nonlinear power electric device generates harmonic current that will make EMI and reduce power factor.The harmonic filtering equipment composed of condenser and in-line reactor has the functions of harmonic filtering reactive compensation.Unlike the traditional condenser set which increases the power factor and amplifying higher harmonic meanwhile under operation,harmonic filtering equipments absorb the harmonic and improve the quality of power supply.In the reactive compensation system,the capacitance shall be calculated according to the power to be compensated,and the in-line resonant frequency in series resonant circuit will be determined by the resistance.The resonant frequency must be less than the min sub harmonic that may happen.

    Design of the Double-channel Audio Signal Real-time Acquisition and Processing System Based on DSP
    YUAN Ru-Xuan, WEI Le, HE Tian-Lu, GAO Zhong-Shan
    . 2011, 24(7):  24. 
    Abstract ( 1308 )   PDF (440KB) ( 830 )  
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    This design scheme adopts TMS320C5509A as the core processor,giving a realization method for composing the speech signal acquisition system with DMA and McBSP,distributing data buffers reasonably and realizing real-time data updated reliably and steadily.Then the paper expounds in detail the design method of configuration and data interface which connects AIC23B with DSP.Finally,the paper provides a C language program example which introduces data transmission between them.Experimental results of data acquisition show that the system can achieve real-time data processing with high precision and reliability.The system can be used for driver development of personal portable audio communications equipment.

    Design of the Direct Sequence Spread Spectrum System Based on FPGA
    ZHANG Bo-Tao, ZHAO Ju-Yun, LI Jian, YAO Jin-Jie
    . 2011, 24(7):  27. 
    Abstract ( 1709 )   PDF (735KB) ( 876 )  
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    General wireless communication system has many has many shortcomings,for example the poor ability of anti-interference,anti-jamming and anti-multipath performance.This paper proposes a direct sequence spread spectrum system based on FPGA.This design uses 63 bits of code series as spread spectrum modulation code sequences.When sending information code,the information code is modulated by PN code;in the receiver,the information is demodulated.this process improve the system's performance.Both VHDL and principle diagram method are employed to design the circuit in the Altera company Quartus II software.Finally,the circuit is downloaded onto CycloneIII EP3C10E144C8N for debugging,which verifies the feasibility of spread spectrum system.

    Application of the Multi-Computer Communication Mode in the Communication System
    REN Rui-Tao, JIANG Jia-Hong
    . 2011, 24(7):  30. 
    Abstract ( 1644 )   PDF (291KB) ( 939 )  
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    This article takes ATmega32,an AVR microcontroller,as a example to introduce the application principle of Multi-processor communication in the serial communication.Concrete applications and implementations are proposed for sending and receiving program of the software with a brief description.

    Design of a Radar Signal Generator Based on AD9910
    WANG Gang, XU Wan-Cheng
    . 2011, 24(7):  32. 
    Abstract ( 2070 )   PDF (529KB) ( 854 )  
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    This paper firstly introduces the functions and characteristics of AD9910,then discusses a scheme using FPGA control DDS to simulate chirp signal,and finally makes a brief analysis of the simulation results of the scheme.Experimental results show that the frequency spectrum of the radar signal based on this scheme is clean and stable,so it can meet the requirements of radar systems.

    Realization of ISAR Jammer
    HE Shao-Yin
    . 2011, 24(7):  35. 
    Abstract ( 1386 )   PDF (570KB) ( 884 )  
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    Since ISAR has prominent performances and wide military applications,it is urgent to study jamming methods against ISAR,but research to the realization of hardware is relatively weak.In this paper,we introduce a implementation of typical ISAR jammer and discussed the composition and function of the key part in detail.The experimental results of indoor and outdoor show that the jammer has a good interference effect.

    Performance Analysis of the Airborne Radar Warning System
    WANG Jing-Qiang, LUO Lu-Qin, ZHANG Xiao-Jie
    . 2011, 24(7):  39. 
    Abstract ( 1228 )   PDF (685KB) ( 970 )  
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    Airborne Radar Warning System is an important part of the airboard self-defense electronic countermeasure system.This paper introduces its components and functions of the system with emphasis on the analysis of the azimuth determination and azimuth measurement error.The future trend of Airborne Radar Warning System is pointed out.

    Countermeasures and Simulation for Airborne Towed Radar Active Decoy
    NONG Chun-Li
    . 2011, 24(7):  42. 
    Abstract ( 872 )   PDF (465KB) ( 709 )  
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    In the modern electronic warfare,as a new jamming technique,TRAD (Towed Radar Active Decoy) can interfere the mono-pulse angle measuring system effectively and becomes a great threat to the single-pulse radar seeker.In this paper,the jamming principle of TRAD is analyzed.It also proposes a method of ant-jamming-PD radar combines with Gating Speed and Angle Measurement.In the end,this paper analyzes the ant-jamming methods which have been mentioned above through simulation.

    Research on DRFM Jamming Technology for HPRF signal
    WANG Fu-Hong
    . 2011, 24(7):  45. 
    Abstract ( 1405 )   PDF (470KB) ( 797 )  
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    The high frequency signal heavy DRFM jamming technology is studied with focus on the multiple fake target range deception jamming,aiming at high frequency signal characteristics,heavy adopted circulation storage add convolution filter method of generating more false object,so as to realize deception jamming.

    Research on Jamming Technology to Jam Multiple Radar Signals Simultaneously Based on DRFM
    WANG Jian-Long
    . 2011, 24(7):  48. 
    Abstract ( 1313 )   PDF (605KB) ( 798 )  
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    Focusing on the multiple-signals jamming simultaneously,combined with the DRFM technology,the study of the transmit-jamming system is started and the theoretical scheme is proposed.Then simultaneous jamming of LFM signal and Barker code is analyzed and the simulation result is given at last.

    Variable Stator Vane Fault Message Airbus
    WANG Ting
    . 2011, 24(7):  51. 
    Abstract ( 1182 )   PDF (615KB) ( 887 )  
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    This paper analyzes the working principle and typical fault of V2500-5A engine Airbus Variable Stator Vane,and introduces the methods for maintenance and flight operations using FCOM (Fight Crew Operating Manual) or AMM (Aircraft Maintenance Manual) combined with working experience to improve the safety and reliability of the aircraft engines.

    Improvement of the Power Supply Rejection Ratio of the Amplifier Circuit
    LONG Fen, DING Lin
    . 2011, 24(7):  53. 
    Abstract ( 1463 )   PDF (544KB) ( 910 )  
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    In the actual application circuit,the noise and volatility will often be unwittingly introduced into the supply voltage,thus affecting output voltage.To make the circuit stable,one needs to eliminate or suppress the noise generated.Three methods are discussed in this paper to improve power supply rejection ratio amplifier (PSRR): cascode methods,feedback technology,and the design that can reduce the power of the additional output voltage gain of the circuit.A comparison of the simulation data transmission of these three methods show that they can maintain a high gain and are helpful for cascaded amplifier circuit design,and the additional circuitry meets the stability requirement of the of power supply fluctuations.

    Design of a V-band MMW Power Amplifier for Short-Range Detection
    SONG Li-Na, LI Xiao, YE Rong-Qin
    . 2011, 24(7):  57. 
    Abstract ( 1487 )   PDF (908KB) ( 771 )  
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    This paper introduces a design of power amplifier operating at non-atmosphere window waveband,which can be used as short distance detection system on missiles.The circuit designed for this power amplifier is based on MMIC.It uses double electric bridge which has better standing wave at ports,and the power combination is realized by multiple cascading.From waveguide to microstrip,microstrip probe is employed and inserted through E-plane of the waveguide,realizing the transition between double waveguide solid transmission line and microstrip integrated transmission line,and the in-phase wideband power combination/divider.Practical measurements show that at operating bandwidth,the specifications have met the requirements of the design,and larger power output has been realized,thus providing technical assurance for engineering application.

    Performance Analysis of Delay Unbalance in MIMO Distributed Antenna System
    DENG Dan
    . 2011, 24(7):  61. 
    Abstract ( 1526 )   PDF (528KB) ( 869 )  
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    The difference between lines and devices produces delay unbalance for MIMO indoor distributed antenna systems.A theoretical analysis of the impact of delay unbalance on distributed antenna systems is given,which is confirmed by quantitative analysis.Simulation results show that the backward link is not sensitive to the delay difference,and that for forward link,when delay unbalance is CP/2,the performance loss will be 2 dB;and when delay unbalance is 3/4CP,the performance loss will be 8 dB.

    Positioning Principles and Localization Techniques Based on RFID Tags
    HAN Jing
    . 2011, 24(7):  64. 
    Abstract ( 1637 )   PDF (611KB) ( 824 )  
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    Both identity and location are generally key information for indoor services.RFID is an automatic identification technology that enables tracking of people and objects.An obvious and interesting method is to localize RFID tags.However,in indoor environments,signals are harshly impaired and tags have very limited capabilities which pose many challenges for positioning them.This paper reviews the state-of-art of RFID positioning principles and localization technology,explains and classifies RFID localization techniques,and finally discusses the future trends.

    Power Quality Monitor and Data Storage System Based on CAN Bus
    QIN Yin-Shan, ZHANG Guo-Wen, LV Yu-Xiang, ZHAO Qing-Sheng
    . 2011, 24(7):  68. 
    Abstract ( 1760 )   PDF (740KB) ( 802 )  
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    According to the analysis on the traditional power quality pickup assembly,a power quality monitor and data storage system based on CAN bus is proposed.This system designs a fast data transmission platform which can transmit a tremendous amount of data reliably and realize efficiently data communication between the base station and host computer system.Meanwhile,the system can achieve large memory of data by externally enlarging the storage of hard drive with the U-disk read-write module.In addition,these modular circuits for data acquisition,phase-locked frequency multiplication and data communication are also given.The test results show that this system is feasible and all parameters satisfy the design requirements.

    FCM Algorithm with Spatial Information for Effective Medical Image Segmentation
    WANG Li-Ming
    . 2011, 24(7):  72. 
    Abstract ( 1336 )   PDF (1328KB) ( 1020 )  
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    Standard FCM algorithm takes into account the gray information,not the spatial information of the image,so the algorithm is sensitive to noise.In view of the fact that medical image data must contain much noise in the process of  acquisition,the designed algorithm must be robust to noise.The improved algorithm is formulated by incorporating fuzzy spatial information into KFCM_S2,a prior probability is given to indicate the spatial influence of the neighboring pixels on the centre pixel,the new fuzzy membership of the current pixel is then recounted with the obtained probability,and then adjust the distance matrix.To realize fast clustering,the histogram initialization is used at the beginning of the algorithm.Experiment results show that the improved algorithm is more efficient and more robust to noise than the standard FCM and KFCM_S2.

    Identification of Parameters from Motion Blurred Images Based on Cepstrum Research
    SU Jun
    . 2011, 24(7):  77. 
    Abstract ( 1114 )   PDF (619KB) ( 948 )  
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    In order to identify the parameters of restoration accurately,an identification method based on cepstrum domain is presented in this paper.Preprocessing method and radon transformation of the cepstrum are employed to identify the blur direction,and then acquire the blur length.Experimental results covering dozens of artificially blurred images and real images show that the proposed method is simple accurate and robust.Final restoration effect is good,and the restored images also validate the usability.

    Method for Vehicle Speed Detection Based on Camera Calibration
    LI Peng
    . 2011, 24(7):  80. 
    Abstract ( 1289 )   PDF (576KB) ( 726 )  
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    The paper focuses on camera calibration and analyzes the principles and common methods of camera calibration for the actual situation as well as application requirement of highway,and the use of homographic matrix-based camera calibration algorithm.The camera calibration mesh region will detect the vehicle in speed detection.The results show that this method is easy to implement with high detection accuracy,and the vehicle average speed accuracy is over 90%.

    Medical Diagnosis Expert System Based on PCA and CBR
    HOU Shan-Shan
    . 2011, 24(7):  82. 
    Abstract ( 1084 )   PDF (507KB) ( 794 )  
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    A medical diagnosis expert system is constructed by combining the principal components analysis and the case-based reasoning.The proposed method of WRS-PCA is the improvement of RS.And the nearest neighbor ratio search method is proposed based on the values most similarly match to improve the retrieval.

    Design of the Virtual Experiment System Based on LabVIEW
    CHEN Chang-Xin, MA Ying-Zhuo, DAI Yue-Song, DONG Li-Ke, SUN Zheng-Xi
    . 2011, 24(7):  85. 
    Abstract ( 1809 )   PDF (824KB) ( 760 )  
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    In view of the superior signal processing of virtual instrument technology,a virtual experimental system is designed using LabVIEW for the experimental teaching of Signal and System.

    Embedded Video Capturing System Based on  S3C2440 Processor
    LIU Yang, PAN Qing-Long, HAO Shuai
    . 2011, 24(7):  88. 
    Abstract ( 1642 )   PDF (784KB) ( 845 )  
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    The article based on the deep research about the embedded development,provides a solution for real-time video capturing system based on embedded S3C2440 processor.Through constructing the environment of embedded Linux development  it optimizes T.264 encoder and modifies the video driver and c/s software to implement the system's normal operation.

    A New Template Method for Image Edge Extraction
    LIU Yu, LIU Yan, LV Shu-Jing
    . 2011, 24(7):  92. 
    Abstract ( 1905 )   PDF (1236KB) ( 733 )  
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    A new horizontal template and vertical template algorithm is proposed in view of the algorithm complexity and programming difficulty using Laplacian operator and gradient operator extracting image edge.By simulation experiment,the image edge is extracted which is better than the edge image using gradient operator extraction.By improving the algorithm,the time of Image Edge Extraction is reduced with little image Information missing.The algorithm provides valuable reference for further research into the locating and matching of image.

    Measurement Method of DME/P Simulator System Delay
    LI Zhan-Ming, WEN Xiu-Qin
    . 2011, 24(7):  97. 
    Abstract ( 1378 )   PDF (429KB) ( 1060 )  
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    It introduces in detail about the system delay (0km delay) measurement method and the way to realize of a precise distance measurement equipment simulator.In this way,the system delay of the precise distance measurement equipment simulator can be measured by rule and line,the problem to fix the reference system delay of the precise distance measurement equipment simulator can be effectively solved,further to meet the requirement for the usage in practice.

    Solution to Configuration of C54x Series DSP Multiple Processors
    ZHANG Hua
    . 2011, 24(7):  100. 
    Abstract ( 1090 )   PDF (898KB) ( 839 )  
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    The simplified downloader cables expand the available DSP target system's number,which is limited to only one when it comes to DSP emulator.A computer is enable to successively configurate as many DSP target systems as the number of USB interfaces in it,when each downloader cable connects the computer's USB interface and the DSP target system's HPI interface.This solution is particularly applicable for program debugging of coordination operation system based on DSP multiple processors.

    Research on LMS Adaptive Beamformer
    WANG Gui-Bao, LIN Zhong-Chao, WANG Lan-Mei, JIANG Xiao-Jie
    . 2011, 24(7):  103. 
    Abstract ( 1607 )   PDF (506KB) ( 837 )  
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    The performance of least mean square error (LMS) algorithm and normalized NLMS algorithm was researched in this paper.The factors that affecting beamformer were ananlysed and large amount of simulation was made to show their influence.The performance and convergence error of LMS and NLMS was campared and the simulation verified that NLMS was superior to LMS.

    DHCP Network Construction and Implementation
    CAO Rong
    . 2011, 24(7):  106. 
    Abstract ( 1461 )   PDF (721KB) ( 773 )  
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    This paper analyzes the working principle of DHCP,sums up the location of DHCP server in the network,and describes the 80/20 rule commonly used for IP network.The building of network environment by combining MSR30-20 and VPC Win03,along with the presentation of network topology,achieves the relay agent function of router and DHCP server function of virtual Win03.The topological structure overcomes the shortcoming of experimental environment,namely only with XP system but without Win03 system,and makes up for the deficiency,namely the separate explanation of router and Win03 DHCP functions in the process of teaching.Theoretical analysis and verified results proves the feasibility of DHCP configuration relay agent.

    Algorithm for Rapid Acquisition of PN Code Based on Parallel FFT
    HU Juan
    . 2011, 24(7):  109. 
    Abstract ( 1520 )   PDF (583KB) ( 908 )  
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    Spread spectrum communication is a system of expanding the baseband signal spectrum to wide band and transmitting.Rapid acquisition of pn code is a key baseband technology of Straight extender system.This paper achieves the spectrum analysis on multiple input signals,doppler frequency detection of carrier and pn code synchronous position search by adopting a parallel FFT algorithm based on the maximum likelihood estimation,and finally gives Matlab simulation and RTL circuit diagrams.This algorithm has been put into practical use in engineering and shows good effect in improving multi-channel spread spectrum signal and receiving system capture time.

    Simulation Analysis about the Effectiveness of the 3W Rule
    ZHANG Lei, LI Hui-Wu, QIU Zi-Jing, HUA Rui-Xia, GUO Qian, XIE Jun
    . 2011, 24(7):  112. 
    Abstract ( 1813 )   PDF (599KB) ( 882 )  
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    3W rule is an experiential method of the routing which is used to reduce the crosstalk of the tracks on printed circuit board.The study of its effectiveness is valuable for engineering application.In this paper,we use HyperLynx software to simulate the effectiveness of the 3W rule,and explore the impact of some factors,such as line margins,line length,dielectric thickness and dielectric constant of the parallel microstrip on the crosstalk.The results indicate that the 3W rules can reduce about 70% of the crosstalk in generally.therefore selecting the appropriate parameters of the parallel microstrip line can make the 3W rule work better.

    Analysis and Simulation of LFM Pulse Compression
    QIU Li-Yuan
    . 2011, 24(7):  117. 
    Abstract ( 1669 )   PDF (498KB) ( 944 )  
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    Pulse compression(PC) is one of the most important technology of radar signal processing.The article first introduces the methods of LFM pulse compression and sideband suppression,then presents the simulation results,and finally analyses the effect of Doppler shifting on results,the RMS and the transform of signal magnitude and bandwidth after pulse compression.Simulation indicates that pulse compression can increase the target detection range while retaining good resolution when the radar transmission power is limited.

    Transplant of Osip Protocol Stack onto the μc/os System and its Application
    LIU Feng, ZHANG Zhi-Pin
    . 2011, 24(7):  120. 
    Abstract ( 1176 )   PDF (462KB) ( 789 )  
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    SIP is one of the important protocols in NGN(Next-Generation Network).In this paper,the basic principle,composition and function of SIP are introduced briefly.A detailed analysis is made of the Osip and eXosip of the open-source SIP protocol stack,and the Osip and eXosip are transplanted onto the μc/os system as a SIP client.A SIP Client based on μc/os OS is designed in which the multiuser can register on the SIP server,and the SIP Client can answer calls from any user on the SIP server.

    A New Rate Control Algorithm of JPEG2000 and its DSP Implementation
    ZENG Yong
    . 2011, 24(7):  122. 
    Abstract ( 1233 )   PDF (617KB) ( 789 )  
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    A new rate control scheme for JPEG2000 image compression is presented,it makes the coding efficiency of JPEG2000 compression standard greatly enhance.Based on the progressive pass truncation encoder,and in conjunction with the drill bit-plane truncation algorithm,it greatly reduced the amount of redundant code and algorithm complexity.At the same time,after extensive testing,the PSNR of this algorithm is merely lower by 0.05 ~ 0.1 dB than the JPEG2000 standard compression algorithm.

    An Improved Algorithm for Dynamic Scene Stitching with Dynamic Programming
    XU Guang-Zhu, ZHU Bing-Lian, FENG Jian-Jun
    . 2011, 24(7):  126. 
    Abstract ( 1067 )   PDF (816KB) ( 862 )  
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    In view of the simultaneous question of (A) Large exposure difference and (B) Moving Objects in dynamic scene stitching,this paper proposes a technique which overcomes these limitations.This technique has three steps.The first step resolves the match of input images.The second step researches the best seam while the third step stitches the pictures with the help of Poisson's equation.Experimental result shows that this algorithm can avoid the dynamic elements and prevent ghosting.

    Crossing Location Technology
    WANG Jun
    . 2011, 24(7):  129. 
    Abstract ( 1644 )   PDF (581KB) ( 813 )  
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    Relevant precision expressions by expounding theory of Bi-static DOA passive location is deducted in this paper.According to the theory,Geometric Dilution of Precision(GDOP) and relative error curve were given,then each positional parameters which affect the locating accuracy is analyzed.Finally,the simulation results and performance analysis provide operational technical principle for such a system in battle.

    Orthogonal Code Design Based on the Genetic Algorithm for MIMO Radar
    LI Xiao-Ming, LUO Ding
    . 2011, 24(7):  133. 
    Abstract ( 1925 )   PDF (576KB) ( 774 )  
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    The MIMO radar can exploit the spatial diversity of target scatterers and improve radar performance.However,the MIMO radar systems require that every radar antenna transmits a distinct signal from a set of orthogonal signals in which any two signals are uncorrelated;meanwhile,every signal has to be wideband impulse signal to achieve the high range resolution.To meet the two requirements,an orthogonal code design method based on the genetic algorithm for MIMO radar systems is presented.The simulation results and performance analysis illustrate that the algorithm proposed is efficient and feasible.

    Fault Diagnosis of Gearbox Based on the BP Network and D-S Evidence Theory
    GU Xiu-Jiang, YAO Zhu-Ting, WANG Yu-Jie, QIN Xin-Hong, LIU Yong-Feng
    . 2011, 24(7):  137. 
    Abstract ( 1658 )   PDF (674KB) ( 733 )  
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    In order to avoid inherent defect of single information in the fault diagnosis,and to improve the diagnostic accuracy,the improved BP neural network is combined with the D-S evidence theory.For the three gauge points of gear-box,the improved BP neural network is used for independent and local fault diagnosis,and then the neural network output results of them is fused by D-S evidence theory rules,and the whole gear-box fault diagnosis is obtained.Through the analysis,one can see that the fused diagnosis result is more accurate,and the trust is higher.

    Dynamic Infrared Scene Generator Based on DMD
    ZHANG Er-Lei, QI Ming
    . 2011, 24(7):  140. 
    Abstract ( 1016 )   PDF (722KB) ( 683 )  
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    Dynamic infrared scene generator is one of the important means to test the detection,track and anti-interference performance of the infrared seeker.Taking the development of the electro-optical countermeasures platform of some air-to-air missile for example,infrared images generation software is developed on the basis of Visual C++6.0 and Vega API by using measure data.Real-time infrared images with vary objects and backgrounds in different conditions are generated to simulate the infrared radiation at the pupil of the guide system.The radiation of blackbody is reflected and modulated by digital micro mirror device based on infrared video signal,which is used to test and evaluate the performance of infrared seeker.The results indicate that the system has the advantages of compact structure,high real-time performance,high frame frequency,high resolution,and great dynamic range.

    Synthesis and Applications of Quasi One-Dimensional (1D) Cds Nanostructures
    CAI Jia-Jun, JIANG Peng
    . 2011, 24(7):  144. 
    Abstract ( 1086 )   PDF (1133KB) ( 630 )  
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    This paper discusses quasi one-dimensional cadmium sulfide (CdS) nanostructures synthesis and corresponding devices.Cadmium sulfide (CdS) as a II-VI semiconductor material with band gap at room temperature is 2.42 eV,has a variety of synthesis methods,according to the specific needs and conditions,by adjusting specific parameters of synthesis needs CdS nanostructures and high-quality quasi-one-dimensional CdS nanostructures prepared by high-performance devices.Although the quasi one-dimensional CdS nanostructures synthesis and device fabrication is still in the laboratory stage,their unique optical and chemical properties have been widely used in photochemical battery and energy storage devices.

    Preparation and Activation Technology of the Zno Ultraviolet Electricity Cathode
    XU Hua-Teng
    . 2011, 24(7):  148. 
    Abstract ( 934 )   PDF (831KB) ( 646 )  
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    ZnO photocathodes show extensive prospect in ultraviolet detection.ZnO is a suitable candidate for the UV optoelectronic device applications at room temperature.The relationship between Cr electrode sputtering time and transparency and surface resistance is discussed.The relationship between the dark current and photocurrent are studied.

    Storage Monitor Technology Based on Windows API
    SHANG Ying, ZHANG Kai-Ran
    . 2011, 24(7):  152. 
    Abstract ( 1093 )   PDF (554KB) ( 631 )  
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    For the data file access security in Windows operating system,a Windows file system driver filter based file monitoring system is designed and implemented.First encryption techniques can be introduced to protect the data,and the precondition is the data is still useful.User permissions,U disk authentication,port control and other means are used to monitor such file operations as create,delete,copy,and rename.The implementation is based on the application layer and is effectively to prevent the unauthorized access to classified data files.

    Review of Frequency Measurement Research
    CHEN Li-Feng, MENG Rui, FENG Xi
    . 2011, 24(7):  155. 
    Abstract ( 1552 )   PDF (829KB) ( 1263 )  
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    With the development of electronic technology,the frequency measurement system in the communications,navigation,space science,metrology and other fields are widely used,and thus an increasing demand for high frequency measurements.How to improve the frequency of measurement accuracy,such as,widening the measurement frequency range,high-speed and reliable adaptive frequency measurement can be carried out,is an urgent need to address the problem.Text classification introduced by frequency measurement,combined with the research results,the advantages and disadvantages of each frequency measurement methods are compared.Frequency measurement will be gradually elaborated automated,and has better consistency,which will help reduce errors and improve the measurement accuracy.

    Study on Key Technologies of 4G
    HE Yan-Peng
    . 2011, 24(7):  160. 
    Abstract ( 1451 )   PDF (495KB) ( 920 )  
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    Based on the analysis of the advantages and disadvantages of 4G,this paper discusses its key technologies.The OFDM modulation in 4G is discussed as a priority among key technologies.The advantages of OFDM make it very suitable for high-speed wireless transmission of the 4G system.OFDM is a potential solution to the high-speed data transmission and one of the most appropriate multiplex access schemes for 4G.

    Development of “Sensor and Detection Technology”
    DAI Hua
    . 2011, 24(7):  163. 
    Abstract ( 947 )   PDF (340KB) ( 577 )  
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    Based on the theory and curriculum design of the course of Sensor and Detection Technology,the Sensor and Detection Technology Training Project combines study and practice from the teaching content and teaching processes.According to actual working positions,the training programs are designed and simulated training environment is created for the students to be familiar with all project production process and to accumulate experience in design and production.At the same time,the course evaluation methods are improved.Process-oriented assessment is adopted,focusing on assessment of professional competence supplemented by written examination of critical theory and skills tests.

    CAD Teaching Laboratory Management System Based on Silverlight
    JIANG Xu
    . 2011, 24(7):  163. 
    Abstract ( 1010 )   PDF (347KB) ( 672 )  
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    In order to suit the needs of the development of the teaching CAD laboratory,a synthetic management system is researched and established based on the researched result of partial work.This system contains 5 modules: practical teaching,online management of classes,laboratory institution,equipments management and system protection.Based on Silverlight techniques and by means of WCF,the management system may be realized thus improving the teaching and management quality.

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