Table of Content

20 August 2012 Volume 39 Issue 4

  

Original Articles

Robust video object tracking algorithm based on multi-feature fusion

LI Yuanzheng;LU Zhaoyang;LI Jing

J4. 2012, 39(4):  1-6+45.  doi:10.3969/j.issn.1001-2400.2012.04.001

Abstract ( 1680 )   PDF (5949KB) ( 1251 )   Save

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Object tracking using multiple features has poor performance under complex scenes and when occlusion occurs. Therefore, an algorithm for fusing multiple features adaptively in the particle filter tracking framework is proposed. The tracked object is represented by the fusion of all features under linear weighting, and a new method to estimate the fusion coefficient is also proposed according to the weight distribution of all particles as well as their spatial concentrations, thus improving the reliability of multi features fusion. Besides, a dynamic updating strategy is used to adjust the update speed of each feature template adaptively, thus alleviating the affection of object deformation. According to the confidence of each feature, an occlusion handling strategy is invoked to decrease the influence of partial occlusion. Analysis and experiment show that the proposed method is more robust under complex scenes, and is applicable in the presence of occlusions.

Design of compact microstrip balanced filter with high common-mode suppression

CHEN Jianzhong;LIANG Changhong;WU Bian;WANG Yi

J4. 2012, 39(4):  7-10+16.  doi:10.3969/j.issn.1001-2400.2012.04.002

Abstract ( 1397 )   PDF (1140KB) ( 1153 )   Save

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The traditional microstrip balanced bandpass filter (BPF) usually has disadvanteges of large size and low common-mode suppression. This paper presents a novel compact microstrip balanced BPF with improved performance of common-mode suppression. Firstly, it proposes the differential and common-mode equivalent circuits of the balanced BPF. Secondly, a very compact interdigital coupled resonator is analyzed, which has the characteristic of strong mismatch with common-mode signals. By using this novel resonator, a balanced BPF with good performance and miniaturization can be achieved. Finally, a balanced BPF centering at 2.45GHz is designed and fabricated. Measured results and simulated results are in good agreement.

High performance BiCMOS differential reference voltage generator

ZHAO Lei;YANG Yintang;ZHU Zhangming;LIU Lianxi

J4. 2012, 39(4):  11-16.  doi:10.3969/j.issn.1001-2400.2012.04.003

Abstract ( 1277 )   PDF (1144KB) ( 1162 )   Save

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A high performance BiCMOS differential reference voltage generator with a current summing architecture is presented. The power supply rejection ratio (PSRR) is improved by using feedback-zero compensation. A high precision and low temperature drift are attained in the current summing temperature compensation mode. In the ASMC 0.35μm 3.3V BiCMOS process, the differential reference voltage generator is simulated and tested below: At a low frequency and at 100MHz, the positive power supply rejection ratio (PSRR⁺) is 78.1dB and 66.7dB, respectively, the negative power supply rejection ratio (PSRR⁺) is 72.4dB and 63.8dB, respectively, the average temperature coefficient of the output differential reference voltage is 11×10^-6/℃, the active area is 2.2mm², and the power comsumption is less than 15mW. This proposed differential reference voltage generator can be applied in a 14 bit 100MHz pipeline ADC.

Robust adaptive mismatched filter in MIMO radar

WANG Yong;LIU Hongwei;JIU Bo;YANG Xiaochao

J4. 2012, 39(4):  17-22+80.  doi:10.3969/j.issn.1001-2400.2012.04.004

Abstract ( 1332 )   PDF (1624KB) ( 978 )   Save

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In the presence of unknown transmitting array distortions, a robust adaptive mismatched filter (RAMiF) is proposed, which is cascaded with the robust receiving adaptive beamformer. At the cost of losing some mainlobe level, the sidelobe level of the proposed filter is suppressed effectively, which provides sufficient robustness against the mismatches between the presumed and the actual transmitting steering vectors. Simulation results demonstrate that the proposed filter has adaptive robustness against the transmitting steering vector errors when the signal-to-noise ratio is relatively high.

Fully secure attribute-based broadcast encryption

SUN Jin;HU Yupu

J4. 2012, 39(4):  23-28+154.  doi:10.3969/j.issn.1001-2400.2012.04.005

Abstract ( 1349 )   PDF (475KB) ( 1105 )   Save

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According to the broadcast encryption scheme with wide applications in the real world but to the fact that its security and efficiency can not be taken into consideration in the model simultaneously, a fully secure attribute-based broadcast encryption scheme is proposed by combining Waters dual system encryption and attribute-based cryptography. Based on the standard model, by using the orthogonality property of composite-order bilinear groups and the attribute vector, the scheme can achieve constant-size ciphertext which constrains four group exponents. The scheme is proved by using three static assumptions which do not depend on the number of queries the attacker makes. Furthermore, the analytical results indicate that the scheme of this paper is fully secure and can satisfy the higher efficiency and practical requirement.

Probability model of quantum signaling transmission damage  and repair strategy

YI Yunhui;NIE Min;PEI Changxing

J4. 2012, 39(4):  29-32+73.  doi:10.3969/j.issn.1001-2400.2012.04.006

Abstract ( 1392 )   PDF (545KB) ( 962 )   Save

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A quantum signaling transmission scheme based on quantum entanglement, local unitary operation and teleportation is proposed for signaling transmission in a multiuser quantum signaling network with multi-stage hierarchy level network topology. The analytical result shows that the scheme is secure in case of eavesdropping attack including intercept-measure-resend attacks, intercept-replace and adding-ancilla attacks. Consequently, the probability model of quantum signaling transmission damage probability and the repair strategy of the damage of quantum signaling are presented, and the probability model in noise background and non-ideal traditional channel has very low complexity.

Rate control algorithm for the Wyner-Ziv frame for  no-feedback distributed video coding

QIN Hao;QU Bei;SONG Bin;YANG Mingming

J4. 2012, 39(4):  33-38+93.  doi:10.3969/j.issn.1001-2400.2012.04.007

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A rate control algorithm for Wyner-Ziv frames for no-feedback distributed video coding system is proposed. Based on the rate-distortion theory and experimental results, the algorithm first establishes the rate-distortion estimation model (RDEM) for each coefficient band of Wyner-Ziv frames, and determines the model parameters by training. With the proposed RDEM, the algorithm is able to estimate the coding rate for each coefficient band of a Wyner-Ziv frame and choose the optimal quantization matrix accordingly to meet the target rate constraint. Finally, the parity rate estimation for each bit plane of each coefficient band is performed to accomplish the LDPC coding. Compared with the existing no-feedback rate control algorithm, numerical results show that the proposed method can increase the average PSNR (peak signal-to-noise ratio) of reconstructed images by 0.3 to 1dB with little complexity incurred at the encoder.

Joint channel and power allocation for the uplink in  multi-cells of the WRAN

LIU Yingting;LI Chenxi;ZHANG Hailin;HAN Kun;LIU Shuhua;LU Xiaofeng

J4. 2012, 39(4):  39-45.  doi:10.3969/j.issn.1001-2400.2012.04.008

Abstract ( 1720 )   PDF (744KB) ( 1024 )   Save

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A new WM-CPE coexistence model is established based on the analysis of the interference between consumer premise equipments (CPEs) and wireless microphones (WMs) in the Wireless Regional Area Network (WRAN). The proposed joint channel and power allocation game for the uplink in multi-cells of the WRAN can be formulated as a potential game and it is guaranteed to converge to a Nash equilibrium when the best response strategy is performed after observing the opponent's response. The user's utility function and the system's potential function are given and proved. The proposed algorithm has lower complexity than the brute-force (BF) search. Simulation results verify the convergence and correctness.

Novel passive radar location algorithm based on Memetic  optimization by using the bearing-and-Doppler frequency

TONG Fei;WANG Jun;LI Hongwei

J4. 2012, 39(4):  46-51+102.  doi:10.3969/j.issn.1001-2400.2012.04.009

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As the fast and high accurate location information is difficult to obtain in passive radar systems, this paper proposes a passive radar location algorithm based on Memetic optimization by using the bearing-and-Doppler frequency, which is the first time to introduce the Memetic algorithm to the passive location field. With a newly designed decreasing direction as the Memetic local search strategy, the target location is transformed to a problem of function optimization. Experimental results validate that the new algorithm, realizing a fast and high accurate target location, can not only retain the relative error under a low level so that the location accuracy can approach the Cramer-Rao Bound steadily, but also converge to the optimal solution more rapidly than evolutionary algorithm location.

Estimation of the number of sources via minimal redundancy fitting

YANG Zhiwei;HE Shun;ZHANG Juan;XU Qing

J4. 2012, 39(4):  52-56.  doi:10.3969/j.issn.1001-2400.2012.04.010

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To alleviate the performance deterioration in the estimation of the number of sources with a low signal-to-noise ratio and/or secondary data deficient scenario, a new method based on the minimum redundancy fitting test is presented. The approach is performed in three stages. First, we employ a subspace tracking algorithm to calculate the one-dimensional noise subspace, and then a redundant array steer matrix is obtained based on the spatial spectrum which corresponds to the noise subspace. Redundant steer vectors are removed via minimum redundancy fitting and the number of sources is obtained. The effectiveness of the presented algorithm is verified by numerical simulation.

Lattice-based signature scheme in the standard model

WANG Fenghe;HU Yupu;JIA Yanyan

J4. 2012, 39(4):  57-61+119.  doi:10.3969/j.issn.1001-2400.2012.04.011

Abstract ( 2170 )   PDF (454KB) ( 965 )   Save

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To improve the efficiency of the Bonsai trees signature which was proposed in Eurocrypt'10, utilizing the Bonsai trees algorithm, a new lattice-based signature scheme is proposed. Based on the hardness of the short integer solution problem (SIS), the proposed scheme is provably existentially unforgeable under a static chosen-massage attack in the standard model. Moreover, the public-key length of our proposed signature is (k+1)mn log q bit while the bonsai trees signature's is (2k+1)mn log q bit; the signature length of message is (1+k/2)m log q bit while the Bonsai trees signature scheme's is (k+1)m log q bit. So the proposed signature scheme is more efficient than the Bonsai trees signature.

New equivalent method for multi-spectral optical coefficients

HOU Yanbin;QU Xiaochao;CHEN Duofang;CHEN Xueli

J4. 2012, 39(4):  62-66+196.  doi:10.3969/j.issn.1001-2400.2012.04.012

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On the basis of the establishment and analysis of the bioluminescence tomography (BLT) system equation, a new equivalent method for multi-spectral optical coefficients is proposed, which convertes the multi-spectral BLT problem into the equivalent mixed-spectral version, thus reducing the dimension and overhead of the system equation. Results demonstrate that this new source weighted method (SWM) is much more accurate and robust than the available arithmetic average method (AAM), keeping the relative error of less than 5％.

Power inversion array based on particle swam optimization

ZHANG Biao;WANG Jieling;TIAN Bin;YI Kechu

J4. 2012, 39(4):  67-73.  doi:10.3969/j.issn.1001-2400.2012.04.013

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The convergent speed and steady-state misadjustment error can not be improved simultaneously in the power inversion array when using the least mean square(LMS) algorithm. However, the recursive least squares (RLS) algorithm used in the power inversion array also bears a burden of large computation and is realized with difficulty. To solve this problem, the particle swarm optimization (PSO) algorithm adopting the time-varying fitness function is proposed. By means of introducing such techniques as the variable inertia factor, variable maximum speed and selection mechanism, the algorithm can adjust the weight coefficients adaptively to find the best solution. The power inversion array using the PSO algorithm can place nulls to suppress jamming effectively.

Adaptive particle swarm optimization via disturbing  acceleration coefficents

JIANG Jianguo;TIAN Min;WANG Xiangqian;LONG Xiuping;LI Jin

J4. 2012, 39(4):  74-80.  doi:10.3969/j.issn.1001-2400.2012.04.014

Abstract ( 1233 )   PDF (503KB) ( 958 )   Save

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The Particle Swarm Optimization (PSO) is an evolutionary method which is used to search for the global optimal solution by iteration. However, PSO has the problem that the particle swarm algorithm falls easily into premature convergence and has a low search efficiency. In this paper, after analyzing several existing improved particle swarm algorithms, a new improved particle swarm algorithm is proposed based on the fact that symmetrical particles distribution can enhance the optimation search results. The proposed algorithm can adjust the inertia weight factor adaptively in different phases of the process according to the variation of the cosine function. In addition, the acceleration coefficents based on linear variation are disturbed under a certain condition. Moreover, an appropriate value of the parameter in this condition is determined via experiments. Several classic functions have been used to test this new algorithm and then the results of this new algorithm are analyzed by comparing it with several relevant algorithms in the literature. The results show that this new algorithm can not only improve the convergence speed significantly, but also improve the premature convergence phenomenon.

High resolution range profile compensation algorithm for  the space target with uniform acceleration

LIU Hongchao;JIU Bo;LIU Hongwei;BAO Zheng

J4. 2012, 39(4):  81-86.  doi:10.3969/j.issn.1001-2400.2012.04.015

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By regarding the target echo as the cubic phase signal approximately, a compensation algorithm for space target based on the cubic phase function is proposed. Additionally, the Cramer-Rao bound of velocity and acceleration estimation is deduced with the purpose of evaluating the performance of the proposed algorithm. Numerical results show that the proposed algorithm can estimate the velocity and acceleration of the target and compensate the high resolution range profile under a lower signal to noise ratio,which is important for the following inverse synthetic aperture radar imaging and target recognition.

Quasi-closed-form solution for distributed satellites  InSAR geolocation

LIU Yanyang;LI Zhenfang;YANG Juanjuan;BAO Zheng

J4. 2012, 39(4):  87-93.  doi:10.3969/j.issn.1001-2400.2012.04.016

Abstract ( 1308 )   PDF (635KB) ( 924 )   Save

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This paper deals with the geolocation problem resulting from the generation of digital elevation models (DEMs) via the distributed satellites interferometric synthetic aperture radar (DS-InSAR). Compared with the repeat-pass InSAR system, the slave SAR in the DS-InSAR system working in a bistatic mode possesses a more complicated focusing geometry, which makes it difficult to get the closed-form solution to geolocation equations. By utilizing the geometry of the master image, a novel equivalent phase center method for the distributed satellites InSAR geolocation is proposed. Accordingly, the quasi-closed-form solution with high accuracy is given. The accuracy of the quasi-closed-form solution is validated by theoretical analysis and simulation results.

Threshold voltage model of the surface Ge channel pMOSFET

DAI Xianying;LI Zhi;ZHANG Heming;HAO Yue;WANG Lin;ZHA Dong;WANG Xiaochen;FU Yich

J4. 2012, 39(4):  94-97+113.  doi:10.3969/j.issn.1001-2400.2012.04.017

Abstract ( 1381 )   PDF (527KB) ( 979 )   Save

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An analytical model of the threshold voltage of the Ge channel pMOSFET is developed by solving Poisson's equation for the first time. The short channel effect(SCE) and drain induced barrier lower(DIBL) are in corporated into the model. Simulated results show satisfactory agreement with experimental data. Simulated results also show that the channel length, Ge content, substrate doping concentration, and gate oxide thickness affect the threshold voltage greatly. Simulation results show that, when the channel length is less than 200nm, the SCE and DIBL affect to threshold voltage greatly, and when the channel length is more than 500nm, the effect of the SCE and DIBL on the threshold voltage can be ignored.

Fast computation of the wide-band radar cross section  of arbitrary objects

MA Ji;GONG Shuxi;WANG Xing;ZHAO Weijiang

J4. 2012, 39(4):  98-102.  doi:10.3969/j.issn.1001-2400.2012.04.018

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The adaptive integral method(AIM)combined with the best uniform approximation is applied to analyze the scattering of an arbitrarily shaped perfect electric conductor over a wide frequency band. It is time-consuming to obtain the wide-band radar cross section(RCS)by repeating the calculation at each single frequency point. To solve the problem more efficiently, the Chebyshev nodes within a given frequency range are determined firstly, and the surface electric currents at those nodes are computed with AIM. According to the best uniform approximation, the electric currents can be obtained at any frequency within the given frequency range. Thus the wide-band RCS of the objects can be acquired. Due to the fact that the AIM is employed to reduce matrix storage where full matrices are stored in a sparse form and to accelerate the matrix-vector multiplications, the algorithm reduces the solution time. Finally, numerical examples are presented to demonstrate the accuracy and efficiency of this technique.

Complex scene text location method based on WTLBP and SVM

LIU Xiaopei;LU Zhaoyang;LI Jing

J4. 2012, 39(4):  103-108.  doi:10.3969/j.issn.1001-2400.2012.04.019

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To reduce the false alarm rate in a complex scene text location, a text mode description method based on the combination of wavelet transform and LBP is proposed, which is used to classify candidate text regions as text or non-text regions. In the procedure of text location, firstly, the stroke edge is used to detect text regions, and the candidate text regions are obtained; secondly, WTLBP features of candidate text regions are extracted, and the support vector machine (SVM) classifier is employed to determine whether candidate text regions are text regions or not. Experimental results show that the proposed text feature is of high discrimination, and that using it in the procedure of verification can greatly reduce the false alarm rate of the scene text location.

Analysis of the Si micro actuator with large displacement  and low voltage

TIAN Wenchao;JIA Jianyuan

J4. 2012, 39(4):  109-113.  doi:10.3969/j.issn.1001-2400.2012.04.020

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The development trend of the micro actuator is the large-displacement, low-voltage and fast response. At present, the main drive mode of the micro actuator is the electrostatic transverse loading. However, its drive voltage is too high and deformation is too small. The model of a micro actuator with large displacement low voltage is presented based on the principle of the vertically-horizontally bending. The elastic force is transformed from the restoring force to the driving force. The deflection equation of the micro beam is derived. Simulation shows that the displacement is as large as 145μm and the driving voltage is as low as 5V. The displacement and driving voltage are superior to those of the current micro actuator.

Distinguishing attacks on generalized self-shrinking generators

LI Xuelian;GAO Juntao;HU Yupu;ZHANG Fengrong

J4. 2012, 39(4):  114-119.  doi:10.3969/j.issn.1001-2400.2012.04.021

Abstract ( 1368 )   PDF (473KB) ( 862 )   Save

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With simple construction and easy implementation, the generalized self-shrinking generator is a keystream generator intended to be used as a stream cipher. This paper investigates the security of the generalized self-shrinking generator. We propose two distinguishing attacks on the generalized self-shrinking sequences by using the feedback polynomial and the sequence v. The results show that the attacker can launch a distinguishing attack by choosing the h^w-1 keystream bit of the generalized self-shrinking generator, if the feedback polynomial f(x) is of hamming weight w and degree h. On the other hand, if the hamming weight of f(x) is low, then the attacker can launch a distinguishing attack, and the attack complexity depends on the weight of f(x).  Therefore, neither type of the polynomials can be chosen as the feedback polynomials of the generalized self-shrinking generator. Users should choose the feedback polynomial carefully, otherwise the stream cipher can suffer from distinguishing attacks.

Automatic detection of security protocols with XOR

YANG Yuanyuan;MA Wenping;LIU Weibo;YU You;GU Jian

J4. 2012, 39(4):  120-125+183.  doi:10.3969/j.issn.1001-2400.2012.04.022

Abstract ( 1007 )   PDF (432KB) ( 895 )   Save

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Since most of the current model checking tools can not detect security protocols with XOR, a new model checker named SAT＃ is proposed. By defining the concept of abstract XOR term and its reduction rules, the new model greatly reduces the number of XOR messages produced by the intruder, and resolves the state space explosion problem resulting from the introduction of XOR operations, on the basis of which by adding the rewrite rules of XOR based on the abstract XOR term, the new model endows the intruder with the XOR operations, and thus is able to automatically detect the security protocols with XOR. The detection results of the BULL protocol show not only the practicality of the abstract XOR term but also the reliability of the SAT＃.

Design of a high-resolution frequency meter combined with the DDS

BAI Lina;ZHOU Wei;ZHAO Jie;ZHANG Qinglan

J4. 2012, 39(4):  126-130+160.  doi:10.3969/j.issn.1001-2400.2012.04.023

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This paper describes the method for designing a high-resolution frequency meter based on the DDS (Direct Digital Synthesizer) using a simple circuit. In this method, DDS is used to track the value of the measured frequency and synthesizes automatically appropriate frequency standard signals. This method is applicable to measuring signals within a wide range of frequency. Prototype measured data show that the high-resolution frequency meter can reach the magnitude of 10^-12/s.

Warship target detection algorithm based on  cartoon-texture decomposition

WANG Weiwei;XI Dengyan;YANG Gongpeng;ZHOU Lijuan

J4. 2012, 39(4):  131-137.  doi:10.3969/j.issn.1001-2400.2012.04.024

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Based on cartoon-texture decomposition, we propose a scheme for detection of warship targets in optical remote sensing images. First, an image is decomposed into a structure component and a texture component. The structure component contains objects of large sizes such as sea, lands and clouds that possiblly appear, while the texture component contains objects of comparablly small sizes such as warship targets and details of other objects. In order to reduce the influence of the details on the detection of warships in the texture component, we remove the details of lands, clouds and sea from the texture component by using the structural information of these objects. Finally, the ship targets are enhanced by using Gabor filtering. Experimental results and data analysis show that the new algorithm efficiently improves the detection rate and significantly reduces the false rate.

Method for estimating power spectral density in  pulsed carrier phase noise measurements

CHEN Xiaolong;WANG Jiali;SUN Lu;FENG Dan

J4. 2012, 39(4):  138-143.  doi:10.3969/j.issn.1001-2400.2012.04.025

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To improve the performance of power spectral density estimation used in pulsed carrier phase noise measurement, the mathematical model of phase noise is established, the relation between phase noise and power spectrum of noise is analyzed, and a power spectral density estimation method based on the Welch method is developed. According to this method, the scheme for the data segment and the length of the window function are determined by the pulsed modulation parameter of the measured signal. Simulation results show that the proposed method has better performance on spectrum estimation than the existing ones.

Low-redundancy compressed sensing measurements

SONG Xiaoxia;SHI Guangming

J4. 2012, 39(4):  144-148+171.  doi:10.3969/j.issn.1001-2400.2012.04.026

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To solve the difficult problem that it is difficult for traditional compression methods to efficiently reduce compressed sensing measurements, this paper proposes a method for obtaining the low-redundancy compressed sensing measurements based on the mutual coherence theory, set theory and sequential compressed sensing. In the proposed method, according to the mutual coherence theory, a smaller measurement set is obtained by removing some redundant measurements from the original measurement set in the premise of ensuring signal reconstruction. Then, the smaller measurement set obtained above is classified into the key set (only including key measurement) or the non-key set (only including non-key measurement) according to the important degree of each measurement for signal reconstruction. And some non-key measurements are eliminated iteratively in the premise of ensuring signal reconstruction until the measurement set does not contain a non-key measurement again. Experimental results show that the proposed method can only take 40 to 70 percent of the original measurement set to obtain almost the same reconstruction quality as that by the original measurement set.

Structural topology optimization using a level-set method  based on structural fatigue reliability analysis

LIU Guoliang;CHEN Jianjun;MA Hongbo

J4. 2012, 39(4):  149-154.  doi:10.3969/j.issn.1001-2400.2012.04.027

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Based on the stress-strength interference theory for the fatigue reliability of structural elements, the probability and non-probability fatigue reliability of elements are studied and a new topological optimization method is presented. This method combines with the level set method for structural topology optimization, takes the minimized structural flexibility as the objective function, and chooses the volume and fatigue reliability requirement as constraint functions. The constraints of fatigue reliability are processed explicitly before optimization, which simplifies the optimization course, avoids complicated iteration operations and raises the computing efficiency. The results of engineering examples indicate the validity and rationality of the proposed method.

Visual similarity index for image quality assessment

CUI Li;CHEN Yukun;HAN Yu

J4. 2012, 39(4):  155-160.  doi:10.3969/j.issn.1001-2400.2012.04.028

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Low level features are widely used in computer vision for acquiring information from outside circumstance and responding to it. Considering that low level features provide a rich source of information about luminance distribution, object organization and foreground/background configuration, their difference reflects the structural change of images. Based on the fact that the human vision system always focuses on the local neighborhoods around gazing positions, similarity between corner and edge of images is estimated locally and combined into an image quality metric, namely low-level features based similarity measure (LFSIM). Extensive experiments based upon five publicly-available image databases with subjective ratings demonstrate that LFSIM performs much better than traditional peak signal noise ratio (PSNR) and structural similarity measure (SSIM), and is even competitive to the state-of-the art image quality assessment algorithms information fidelity criteria (IFC) and visual information fidelity (VIF), which are developed on the basis of natural scene statistics.

Improved extending orthogonal space-time block coding

TIAN Xinji;NI Shuiping;SONG Cheng;ZHAO Wei

J4. 2012, 39(4):  161-166.  doi:10.3969/j.issn.1001-2400.2012.04.029

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The extending orthogonal space-time block code is constituted by the identical orthogonal space-time block code (OSTBC). However, the channel fading coefficient of each branch of each OSTBC is not taken into consideration, and the performance of the extending orthogonal space-time block code can be improved further. For this problem, an improved extending orthogonal space-time block code is proposed, in which a proper rotation is set at each signal of branches of some OSTBCs. Since the rotation angles are designed to maximize the effective channel gain, the effective channel gain is increased and the performance is improved. Analysis and simulation show that the system performance is improved, and that the computational complexity is also greatly reduced with only a few bits increase in feedback information.

Dualband left-handed metamaterial composed of  the oblique triangular open-loop pairs resonator

LI Wenqiang;CAO Xiangyu;GAO Jun;YAO Xu;LIU Tao

J4. 2012, 39(4):  167-171.  doi:10.3969/j.issn.1001-2400.2012.04.030

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A method for realizing dualband left-handed metamaterials is presented. By integrating the magnetic resonator plus wire with the magnetic resonator, a novel left-handed metamaterial based on the Oblique triangular open-loop pairs resonator (OTOR) is presented. By analyzing the distribution of the surface current, electric field and equivalent circuit, the combined structure exhibits double LH passbands. The first LH passband is decided by the OTOR+Wire, while the second LH passband is decided by the OTOR. Simulation and experimental results and analysis verify this design. Furthermore, the idea can help us to design negative-index materials with multibands.

Novel design for the quasi orthogonal space-time block code

MA Tianming;LI Fengrong;SHI Yusong;WANG Yingguan

J4. 2012, 39(4):  172-177.  doi:10.3969/j.issn.1001-2400.2012.04.031

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A quasi orthogonal space-time block code scheme is proposed and simulated by MATLAB based on the analysis and study of the current Quasi Orthogonal Space-Time Block Codes. The scheme uses the improved Alamouti Code as its basic unit to design a Quasi Orthogonal Space-Time Block Code matrix with four transmit antennas, using the method of matrix diagonalization to remove the redundant sparse matrix and reduce the decoding complexity. Final simulation results show that, compared with the Jafarkhani Quasi Orthogonal Space-Time Block Code, this scheme can not only be linearly decoded at the receiver, but also further improve the channel capacity and the Bit Error Rate.

Analysis of the combined-virtual pixels in LED displays

ZHAO Xiaoming;ZHOU Xiaoyuan;ZHANG Jianqi;SHAO Xiaopeng

J4. 2012, 39(4):  178-183.  doi:10.3969/j.issn.1001-2400.2012.04.032

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The combined-virtual pixels technology widely employed in outside LED displays is analyzed in detail, with its essence of low-pass filtering to images' homochromatic via reusing subpixels indicated. And its contribution to resolution of LED displays is analyzed quantitatively using the MTF(Modulation transfer function) as an image quality index. The concept-addressability of LED displays is proposed, and it is pointed out that the combined-virtual pixels technology could improve addressability of LED displays and weaken jagged edges of displaying images. Simulation results verify that the combined-virtual pixels technology fails to improve the display resolution, and even causes the obvious decline in some parts of displaying images.

Methods for testing the low probability of interception performance of radar signals

HOU Xiaolin;YANG Yan;GAO Jianjian;JING Zhanrong

J4. 2012, 39(4):  184-190.  doi:10.3969/j.issn.1001-2400.2012.04.033

Abstract ( 1323 )   PDF (990KB) ( 1040 )   Save

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The concept of Low Probability Interception(LPI) is very important in each part in designing Radar, and most of all, the wave design is the core. In this paper, we analyze the principle of designing LPI waves and the method of testing the designed waves' ability of anti-deinterleaving. We give a way of calculating the intercept factor and a de-interleaving method based on the complexity of designed waves. It is convenient to test many kinds of LPI signals' performance, with accurate and useful results given.

Test and analysis of accuracy of the evaporation duct  measuring instrument

ZHANG Aili;WANG Yanjun;ZHANG Yu

J4. 2012, 39(4):  191-196.  doi:10.3969/j.issn.1001-2400.2012.04.034

Abstract ( 1851 )   PDF (527KB) ( 868 )   Save

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The over-the-horizon detection based on the evaporation duct is one of the current research hotspots in the radar field and the most effective means for enlarging the detection range of the ship radar as well. Obtaining the precise evaporation duct parameter is the key to measuring the atmospheric refractivity accurately. By analyzing the accuracy of atmospheric refractivity obtained by both the frequently-used meteorological instrument and the self-developed microwave refractometer and comparing the actual measurement values achieved by both instruments simultaneously, it is proved that the meteorological instrument cannot measure the real-time fine structure of atmospheric refractivity and can cause a big error. The application of the microwave refractometer with the sensing atmospheric medium can help to measure the real-time fine structure of atmospheric refractivity faster and more precisely. So the microwave refractometer is the current proper instrument to measure the evaporation duct profile precisely.