最新刊期
卷 29 ， 期 6 ， 2001
- 摘要：In the ground short range slowly moving target detection of airborne fire-control radar,the two dimensional clutter spectrum varies with range due to the variation of elevation angle and shows high non-homogeneity.In this case,good detective performance can not be obtained by using either conventional or STAP processing method.In this paper,a compensating method of clutter spectrum is proposed.Transforming data of different range ring with different frequency-shift,it can weaken the non-homogeneity effectively and locate the clutter energy center in a very small area of two dimensional plane.The computer simulation results show good performance and high improvement factor can be obtained when it is used as the pre-processor of STAP and it has the advantages of low complexity and ease of application.关键词：airborne fire-control radar;non-homogeneous clutter suppression;STAP(Space Time Adaptive Processing)4|1550|5更新时间：2025-07-16
- 摘要：A principle of shadow imaging for bistatic radar based on forward scattering is introduced. Joint time frequency characteristics of target signal and ground clutter are analyzed,then a method of eliminating ground clutter in bistatic radar echo by wavelet analysis is presented.A robust motion compensation method——to estimate radial motion parameters of target by time-frequency analysis is presented.Finally,the effectiveness of these methods is shown by the results of computer simulation.关键词：shadow imaging;wavelet analysis;motion compensation2|1189|9更新时间：2025-07-16
- 摘要：Recent studies have shown that performance of MUSIC or other algorithms degrades drastically and even fails with a bad knowledge on array manifold.An approach based on 1-dimensional searching for DOA estimation with unknown intensity coefficients was presented in [1].The ambiguous peaks appearing in certain cases must be eliminated.In this paper,a new method based on generalized eigenvalue decomposition is proposed.Detailed analysis of ambiguous problem is presented and is illuminated by numerical examples.关键词：gain;DOA;ambiguity;generalized eigenvalue2|1070|5更新时间：2025-07-16
- 摘要：Inverse Synthetic Aperture Radar (ISAR) imaging of maneuvering target has received much attention in recent years.In the paper,we first discuss translational motion compensation (TMC),which is usually decomposed into two steps:envelope alignment and autofocus,and find that the existing envelope alignment algorithms are still effective for not too big maneuvering target whose migration through resolution cells (MTRC) does not take place,but the existing autofocus algorithms are not effective for maneuvering target in practice and in theory.According to coherent summation principle,we propose an iterative coherent summation autofocus (ICSA) algorithm,with PGA being a particular case of ICSA.Then we discuss maneuvering target imaging problem,in fact,which is an instantaneous spectrum estimation problem.Most existing algorithms are only effective when scatterers' echoes are linear frequency modulation (LFM) signals.For the situation when scatterers' time-frequency distribution is not linear,we put forward an adaptive chirplet decomposition method to estimate instantaneous frequency and instantaneous complex amplitude of multi-component polynomial phase signals,and propose a fast adaptive chirplet decomposition imaging (ACDI) algorithm by utilizing "Clean" technique.Real data processing proves that the proposed ICSA algorithm and ACDI algorithm are effective.关键词：ISAR;motion compensation;envelope alignment;autofocus;maneuvering target imaging2|1141|3更新时间：2025-07-16
- 摘要：At present,view interpolation based on uncalibrated images is widely studied.In this paper,homotopy transform is first introduced into the view interpolation study,and view interpolation theorem based on perspective homotopy transform is presented.The perspective homotopy transform and its algorithm based on uncalibrated images is presented for non-occlusion scene.The key steps of its implementation are estimate of camera intrinsic and external parameters.The experiment indicated that the choke point of the algorithm implementation was the problem of finding matched points between the different view images.关键词：view interpolation;perspective homotopy transform;non-occlusion;intra-scanline2|1071|0更新时间：2025-07-16
- 摘要：In this paper a face detection algorithm based on template matching and neural network verification is presented.Two types of templates: eyes-in-whole and face itself,are used one by one in template matching for searching face candidates.A three layer perceptron is used in the template matching procedure to verify each face candidate to exclude most of the false alarms.Experimental results demonstrate the feasibility of this approach.关键词：face detection;template matching;multi-layer perceptron2|1793|15更新时间：2025-07-16
- 摘要：This paper presents a fractal image coding method based on the DCT transform that speeds up the matching procedure in the sets of domain blocks.This method compares the few low frequency DCT transform coefficients of the range blocks and domain blocks to find out the matched domain block.In accordance with the properties of the DCT transform,it calculates the contrast scaling and luminance shift conveniently.At the same time,it stores the DCT transform coefficients of the range blocks and domain blocks into a lookup table to reduce the redundancy operations.The result shows that the coding time is reduced evidently,while PSNR is only reduced very little.关键词：fractal image coding;DCT transform;lookup table2|1029|3更新时间：2025-07-16
- 摘要：A new motion model with a tracking algorithm is introduced in this paper to track a maneuvering target such as a sea-skimming anti-ship cruise missile (ASCM) in spherical coordinates.The algorithm is based on a more accurate analysis of the motion of maneuver targets.Unlike previous models that treat uncertainties introduced by maneuvering as general random process,this model takes emphasis on nonlinear relationships between maneuver accelerations.A modified adaptive two-stage Kalman filter,named Two-Stage Adaptive Filter Group (TSAFG),is implemented with this model to track simulated incoming ASCM and other maneuvering targets.It is manifested that the proposed method is simple and effective under many situations,and can be extended to track various types of maneuvers.关键词：tracking;maneuver targets;spherical coordinates;adaptive Kalman filter2|781|0更新时间：2025-07-16
- 摘要：A new method for ARM detection based on Adaptive Linear Prediction Error Filter (ALPEF) is proposed in this paper.The method is proved to be fast,reliable for detecting ARM signal in a very low aircraft to ARM signal ratio.Its mechanism is based on the elimination the strong aircraft signal from the radar echoes.Computer simulation results show that a very good detection performance is achieved in a -20dB aircraft to ARM signal ratio,so that a reliable early warning of ARM launching can be given.关键词：signal detection;ARM;linear prediction error filter;acceleration compensation;FFT2|1297|10更新时间：2025-07-16
- 摘要：In this paper,a new method to solve the electromagnetic shielding problems of a thin cylindrical shell of arbitrary cross section is presented.On the basis of averaged boundary conditions,we use the theorem of discontinuity for the normal derivative of a single-layer scalar wave function.Integral equations of electromagnetic shielding for the thin cylindrical shell of arbitrary cross section are derived,and they are solved by using the method of boundary elements.Compared with the solution obtained by using precise boundary conditions,the method presented in this paper is very simple and convenient.The distribution of electromagnetic fields in the free space outside the shell can be calculated with satisfactory accuracy.关键词：electromagnetic field;thin cylindrical shell;averaged boundary conditions;integral equations;method of boundary element2|704|0更新时间：2025-07-16
- 摘要：Taking into account the multi-channels disturbance and noises with the non-stationary characteristic,time delay estimation based on cyclic correlation parametric approach is proposed in this paper.Multi-path time delays are estimated precisely with this method,and disturbances and noises can be refrained effectively.This method has better performance than the time delay estimation based on correlative and has less calculating amount and more wide applicability than the estimation based on the higher-order cumulant approach.The relevant conclusions are got and verified by the simulation experiments.关键词：cyclic correlation;auto-correlation;positioning;time delay estimation2|1137|6更新时间：2025-07-16
- 摘要：A bit error probability (BEP) computation formula for binary partial-response continuous-phase modulation (PRCPM) with differential phase detection (DPD) and maximum ratio combining (MRC) in shadowed satellite mobile channel is presented in this paper.BEP of PRCPM with DPD and MRC in different measured shadowed mobile satellite channels are computed also.关键词：mobile satellite communication system;PRCPM;differential detection;MRC2|850|0更新时间：2025-07-16
- 摘要：One important issue in the provision of QoS guarantees is the study of the scheduling disciplines to be employed at network switches.In this paper,we strive to combine the simplicity of frame-based schedulers with the performance characteristics of generalized processor sharing(GPS) disciplines,and propose a new scheduling mechanism named Hierarchical Frame-based Fair Queueing(HFFQ).HFFQ can support both real time traffic and non-real time traffic at the same time.In addition,it tremendously decrease the implement complexity by using counters to substitute the computing of system virtual time of other mechanism.At last,we evaluate some performance metrics of the HFFQ,such as fairness,service rate etc,using both analysis and simulation,and the results show that HFFQ has a better performance than that of PGPS.关键词：ATM;VC scheduling;fair queueing;FCFS2|618|0更新时间：2025-07-16
- 摘要：This paper makes qualitative analysis to the performance of soft handover technology of downlink WCDMA(Wideband code division multiple access) system,which will play an important role in the third generation mobile communication system.Taking handover margin as a criterion,it also gives a comparison between hard handover and soft handover.Moreover,the macro-diversity effect has been studied in detail.At the end of this paper,some equations are derived,in which two important parameters,i.e.,multipath characteristics and the user density in the cell,have close relation to the macro-diversity gain.关键词：WCDMA;handover;macro-diversity;SIR2|855|0更新时间：2025-07-16
- 摘要：Space-time channel can be described by vector channel impulse response (VCIR).Estimation of the VCIR is very important for Smart Antenna Systems.In this paper,based on multi-user decorrelation,a blind VCIR estimation method for CDMA with aperiodic spreading code is proposed.The new method has the ability to resist near-far effect.Computer simulation demonstrates that the accuracy of the VCIR estimated by the new method can meet the need to extract DOA and time delay information.关键词：space-time channel;aperiodic spreading;blind estimation2|844|0更新时间：2025-07-16
- 摘要：A novel polarization-agile amplifier-type active microstrip array is proposed,in which the polarization agility and amplification of signal for the whole microstrip antenna array can be realized by electrically controlling one active circuit only.Using corner-fed square patch element,a new 16 element dual-polarized array with high isolation and low cross-polarization is designed.Its co-and cross-polarization radiation patterns are analyzed.The design method of active circuit is introduced,in which by changing the gate voltage of FET of a phase shifter,0°or 90°phase shift between dual ports is electrically controlled,resulting in the agility from the linear to circular polarization.The LNA enhances the active gain by 12-14dB,and improves the VSWR bandwidth and the isolation of the antenna as well.The experimental comparisons between passive dual-polarized arrays and active arrays are presented to verify the theory.关键词：active antenna;microstrip antenna array;polarization;gain;phase shifter2|1170|0更新时间：2025-07-16
- 摘要：A novel small microstrip patch antenna with a C-shaped slot is presented in the paper. The size of the antenna is only 33% of a conventional microstrip patch antenna and is much easier for fabrication than shorted patch antennas. The antenna is theoretically investigated using finite-difference time-domain (FDTD) method and its return loss and radiation properties are presented. For purpose of comparing, method of moment (MoM) results and measured results are also presented and good agreement is achieved. Such an antenna may be useful for applications where reduced antenna size and simplicity are major concerns.关键词：microstrip antenna;full wave analysis;size reduction2|1323|3更新时间：2025-07-16
- 摘要：A new frequency dependent FDTD method using DSP is presented for arbitrary frequency-dispersive medium.The dispersive medium is characterized as a set of infinite-impulse filters (IIR).Two algorithms employing frequency-dependent permittivity and frequency-dependent conductivity are derived.Their stability criteria and numerical dispersion are also studied.In order to demonstrate the effectiveness of this approach, several numerical examples are given in this paper.关键词：dispersive media;FDTD;DSP;IIR2|915|0更新时间：2025-07-16
- 摘要：This paper provides a novel wavelet balance approach for steady-state analysis in nonlinear circuits.Because the proposed simulation algorithm is performed in time domain,it can overcome most of the disadvantages of the frequency domain based methodology,and result in low computational complexity and high simulation precision.Furthermore,an adaptive scheme can be employed to automatically determine the wavelet order in simulation.Some experimental results prove the proposed method to be an effective one.关键词：wavelet balance;Nonlinear Circuits;steady-state analysis2|988|0更新时间：2025-07-16
- 摘要：In this paper,we propose a parameterization design method for the symmetric-antisymmetric multiwavelet filter bank.Then,based on it,we present a new multiwavelet zerotree compression algorithm.Experimental results show that our multiwavelets can perform much better than the commonly used 9-7 biorthogonal wavelet in compression efficiency.关键词：multiwavelet;parameterization;image compression;zerotree2|1060|1更新时间：2025-07-16
- 摘要：A new en-/de-code scheme of OCDMA(Optical Code Division Multiple Access) using optical scanning is proposed in this paper.The principle of optical scanning en-/de-coder is given.The structure of optical scanning en-/de-coder is devised.It can also be seen that all-optical spread spectrum OCDMA en-/de-code can be realized by the proposed scheme of optical scanning en-/de-coder.At the same time,it can provide a scheme to remove the "bottleneck" when optical and electrical exchanges with each other occur.It can also make the OCDMA en-/de-coder integrated easily as well as the access is changed.The speed of the proposed spread spectrum OCDMA scheme is much higher than the speed of the time-spread OCDMA scheme.关键词：optical fiber communication;OCDMA;optical scanning2|756|0更新时间：2025-07-16
- 摘要：The requirements of JVM (Java Virtual Machine)-based distributed computation for networks simulating were discussed in this paper.The architecture adopting central controlling mode and the functions of the developed simulator were described also It was shown by a simplified example of cell-relay network that simulations,executed on 5 computers,are speeded up over 70%.关键词：distributed processing;communication networks simulation;simulator implementation2|841|1更新时间：2025-07-16
- 摘要：In this paper,a new efficient method of feature extraction and combined classification based on wavelet analysis and fuzzy integral is presented in order to identify modulation types of communication signals,which are non-stable and varied in wide range of signal noise ratio (SNR).Accuracy and efficiency of identification are obviously improved.The result of computer simulation has proved its good performance关键词：wavelet;fuzzy integral;feature extraction;combined classification;modulation identification2|1710|5更新时间：2025-07-16
- 摘要：Electron optical properties of magnetic immersed lenses are studied using curved axes theory with wide beam.Principal trajectory equations and paraxial trajectory equations are obtained and all of second-order aberration coefficients are derived by Mathematica.The second-order curved axes aberration of a magnetic immersed lens which has analytic axial field distribution is calculated and a dispersion graph of aperture aberration is also given.It is shown that aberration characteristic of immersed magnetic lenses is very particular.关键词：curved axes;magnetic immersed lenses;electron optics;aberration2|788|2更新时间：2025-07-16
- 摘要：A structure with dynamically controlled anode-short is brought forward,and can be used in the low-side device of power IC with high-side and low-side drive and half-bridge output section.By using this structure the low-side device can operate in IGBT mode while on and in MOS mode while turning off.This makes it a low forward voltage drop and high switch speed,and resolves the contradiction between on-resistance and turning off time effectively.Then a low-side device with high speed and low power dissipation is realized without depressing breakdown voltage,changing process and additional circuit devices.关键词：power IC;dynamic controlled anode-short;high-side and low-side drive;half-bride power output;low-side device;turning off time;forward voltage drop2|928|4更新时间：2025-07-16
- 摘要：In view of parasitic passband in the filtering networks composed of distributed elements,a novel circuit of microstrip bandpass filters is presented in this paper.The filtering porperties of the filter are analyzed.The configurations of the filter and related equations are also presented.The circuit is composed of the parallel coupled microstrip lines and the specific combined transmission lines by cascaded connection,and the sturcture is simple.Theoretical results and experimental results indicate that the novel circuits of microstrip bandpass filters has good performance in harmonic suppression.Using this new structure as output filters in the microwave oscillators or amplifiers,the performance of the system in harmonic suppression will be improved.关键词：specific combined transmission lines;parallel coupled microstrip lines;microstrip bandpass filler;harmonic suppression2|1077|0更新时间：2025-07-16
- 摘要：Techniques of automatic real-time detection of slow-moving point target in the low SNR infrared image sequences are discussed in this paper.After analysis of the traditional sequential hypothesis testing (forward-hypothesis based),aiming at the problems of trajectories-cross and combination inflation due to more start points,a backward-hypothesis based statistical detection algorithm is put forward.The paper also discusses the methods to improve SNR and to denote the trajectories.The experimental results show that the algorithm has good performance.关键词：point target;low-SNR;sequential hypothesis testing;backward-hypothesis2|921|2更新时间：2025-07-16
- 摘要：Multiple-beam antennas have found wide use in a variety of applications involving satellite communications.In this paper a summary of several structure schemes of multiple-beam antennas for satellite communications is presented,and a comparison about their advantages and drawbacks are also made.Some topics to be further researched are pointed out.关键词：satellite communications;multiple beam antennas;spot beam coverage7|7378|11更新时间：2025-07-16
- 摘要：The exact solution of the elliptic cone stripline is derived.The formulas are based on the TEM mode and perfect conductor assumptions.Using the coordinate transform and conformal mapping technique the elliptic cone stripline becomes a plane periodical structure,then using elliptic integral transform to handle the finite width stripline,the exact solutions including the characteristic impedance and capacidance per unit length are obtained.关键词：elliptic cone stripline;coordinate system transform;conformal mapping;characteristic impedance;exact solution2|977|0更新时间：2025-07-16
- 摘要：A new method,mode matching,is presented for the analysis of monopole antennas on a circular disk.This approach is facilitated by placing two parallel PEC grounds above and below the antenna and dividing the space into several subregions reasonably,thus allowing use of cylindrical harmonic expansions in each subregion.Then expansion coefficients are found by enforcing the PEC boundary condition and continuity condition at the regional boundary surface.The current and input impedance of monopole antennas on disk is computed based on the above calculation.For monopole antennas with different circular disc in radius,this method can lead to very good agreements between the theoretical results and the experimental results available in literatures.In addition,this method is efficient since the fields are expressed in closed form.关键词：mode matching method;circular disk;monopole antenna2|805|1更新时间：2025-07-16
- 摘要：3D FDTD methods to model dielectric with arbitrary shapes and thin perfect conductor surface were put forward in this paper.Dielectric was modeled by the average electrical parameters corresponding with component location in mesh.By introducing auxiliary electric and magnetic fields,the modeling of thin metal curved surface was implemented.Dielectric resonators and a conical horn antenna were calculated by the presented methods.The correctness of the methods were showed by comparing the results with those reported in the published papers,and the validity of the modeling methods were also justified.关键词：D-FDTD;modeling of dielectric and thin perfect conductor;mesh average perfect electrical parameter;add electromagnetic field2|1187|2更新时间：2025-07-16
- 摘要：The decoupling problem for Volterra adaptive filter is discussed in this paper.By proposing and analyzing the pseudo-linear combination structure of Volterra filter,a new MSE(mean square error) expression can be obtained.Because the Volterra adaptive filter problem can be described as a constrained optimization one,a fully decoupled Volterra normal equation with block-diagonal input correlation matrix satisfying the MMSE(minimum mean square error) criterion is educed.Then a fully decoupled Volterra filter is designed and the adaptive regulating formulation for the weight vectors of the filter is given out.Simulation results indicate that the proposed method in this paper is efficient.关键词：nonlinear system;Volterra series;adaptive filtering;fully decoupled filter2|1037|6更新时间：2025-07-16
- 摘要：The convergence of fractal image compression coding is discussed in this paper.The definitions of both generalized convergence and normal convergence are given.With the discussion,a new coding algorithm——fractal image compression coding based on generalized convergence (GC-FICC) is proposed here.It is shown that,under the same compression ratio,the quality of the reconstructed image with GC-FICC is improved.关键词：generalized convergence;fractal;image compression;coding2|953|0更新时间：2025-07-16
- 摘要：A new method is developed for fusion of two spatially registered images with differing focus points.At first,a point spread function is defined to describe the blurring degree of objects in an image.The clear object is decided by comparison of the wavelet decomposition components of two original images and two blurred images.Experiments show that this method performs better in preserving edge information for the test images than that of the other image fusion methods.关键词：image fusion;wavelet decomposition2|1182|0更新时间：2025-07-16
- 摘要：The paper investigates the performance of soft decision Viterbi decoding for convolutional codes in Rayleigh fading channels by using a new scheme that combines interleaving technique,soft output of the channel and the information about the channel.The formulations for computing the soft decision metrics with or without Channel State Information (CSI) are presented and the performance gains are demonstrated.In addition,we discuss the influences of quantizer thresholds on the decoding performance.The results are compared with the corresponding conclusions in AWGN channels.关键词：soft decision Viterbi decoding;convolutional codes;Channel State Information (CSI);quantizer thresholds;fading channels2|1547|0更新时间：2025-07-16
- 摘要：An improved rate control algorithm-slice-based rate control algorithm is provided in this paper.Through changing the bit-allocating unit from a picture to a slice,it solves the problem of quality unbalance within a picture caused by using TM5 rate control method.Further more it improves the overall quality of the picture.关键词：MPEG-2;video encoding;rate control2|775|0更新时间：2025-07-16
- 摘要：The paper proposes a new SOI sense-amplifier adopting smart-body-contact technology.Delay time characteristics of the SOI Cross-coupling sense-amplifier were analyzed by Hspice simulation and compared with conventional silicon Cross-coupling sense-amplifier,Delay time reduction of the SOI Cross-coupling sense-amplifier over conventional Cross-coupling silicon sense-amplifier is about 30%,and voltage differential is 0.05V.Finally,the circuit was adopted successfully in CMOS/SOI 64Kb SRAM with 40ns fast access time.关键词：SOI(Silicon on insulator);cross-coupling sense-amplifier;SBC(Smart-Body-Contact) technology2|980|0更新时间：2025-07-16
- 摘要：A new motion estimation algorithm is proposed in this paper.It adaptively selects the full or reduced bit-resolution image for block matching based on the texture complexity of the matching block.In addition,a new telescopic search method using dual-bit-resolution image is adopted.Simulation results show that the proposed algorithm has low computational complexity while achieves good image quality.We have designed a novel systolic-architecture-based search engine that has split data paths.Enhancing the operating parallelism in the low bit-resolution case heightens the throughput.The new motion estimator works at a low clock frequency and a low supply voltage,therefore has lower power consumption.关键词：motion estimation;low bit-resolution;telescopic search;VLSI architecture;parallelism;low power2|826|2更新时间：2025-07-16
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