最新刊期
卷 35 ， 期 6 ， 2007
- 摘要：The image registration error,clutter decorreclation and array error have a great influence on the performance of the distributed synthetic aperture radar ground moving target detection.In this paper,an approach on moving target detection and relocation is proposed based on multi-channel and multi-pixel adaptive signal processing in image domain.Firstly,the multi-channel and multi-pixel joint data is equaled to a simple array model.The real steering vector of the moving target can be estimated through the space projection approach on the condition that there is image registration error.The optimal beam forming approach is used to cancel clutter,and at the same time the cross-track velocity of moving target can be determined by searching for the peak value of the cost function and then the moving target can be relocated on the image.The simulation results indicate this method has a good robustness to image registration error,clutter decorrelation and array error,and the detection performance and the estimation accuracy are improved greatly.关键词：distributed small satellite;ground moving target detection;images registration;optimal beam forming2|1171|9更新时间：2025-07-16
- 摘要：Aimed at the SAR blanketing jamming suppression,a method of three-channel cancellation is proposed.First,principles of the method to suppress blanketing jamming and its influences on SAR imaging are presented in theory,from which the expression of target loss period (TLP) is derived,and then the simulation experiment is carried out.The results show the superiority of the proposed method for SAR anti-jamming in comparison with the method of two-channel cancellation.In addition,this method can be extended to the general circumstance of N-channel cancellation processing,which allows the method to be applicable,effective,and theoretically complete.关键词：synthetic aperture radar(SAR);anti-jamming;blanketing jamming;three-channel processing2|1008|12更新时间：2025-07-16
- 摘要：The altitude of a target can only be estimated roughly by very high frequency(VHF) radar for this kind of radar has a wide beam which is usually be split because of the reflection from the ground.To resolve this problem,the paper proposes an accurate and effective method for measuring the altitude based on beam split,namely,Phase-comparison and Amplitude-comparison.In this measuring system,several antennas of different heights are utilized.Owing to the certain relationship among the phases of the split beams of different antennas,the phases of the echoes can be used to determine the elevation region the targets locate.Using "Amplitude-comparison" of echoes from various antennas to pick up the normalized error signals,the elevation of the target is obtained through looking up the table.An analysis of the effect on the altitude measurement accuracy caused by the roughness of ground is presented.This method has been used in some radar,and has been successfully used in the experiment of the altitude measurement in VHF radar.It has been proved that this approach is effective to measure the altitude of a target which has a rather low elevation.关键词：VHF(Very High Frequency) radar;altitude measurement;multi-path;beam split3|1431|15更新时间：2025-07-16
- 摘要：This paper analyses the geometry and principle of distributed InSAR(Synthetic Aperture Radar Interferometry) geolocation,and provides a complete closed-form solution to the geolocation problem.Meanwhile,it analyses the sensitivity of the closed-form solution,and proposes the formulations of geolocation precision criterion and system parameters precision criterion.The analysis indicates that the property of geolocation geometry is determined by the angle among sightline vector,baseline vector and master satellite speed vector.The angle made up of sightline-baseline plane and sightline-speed plane is a key parameter,and the bigger the angle,the better the geolocation geometry is.Finally,in Cartwheel formation,a Monte Carlo simulation is performed to prove that the precision analysis is correct.关键词：distributed InSAR(Synthetic Aperture Radar Interferometry);geolocation;closed-form solution;precision criterion2|635|9更新时间：2025-07-16
- 摘要：According to the characteristic that the bandwidth of spaceborne SAR(Synthetic Aperture Radar) is generally quite wide,a method called "Sub-band Double Carrier Frequency Conjugated Processing" is presented.The approach can decrease the equivalent central frequency of the synthetic signal and remove the Doppler ambiguity.Consequently,Keystone transform can be used to correct the linear range migration of the fast moving target with low input SNR.After the target range curvature is corrected,time-frequency analysis can be used to implement low resolution imaging and targets detecting.The radial velocities of targets can be obtained from targets detection,and high resolution imaging process can be completed to each moving target.The simulation results show the effectiveness of the new method.关键词：SAR(Synthetic Aperture Radar);moving targets detection;moving targets imaging;Keystone transform2|885|4更新时间：2025-07-16
- 摘要：The joint criterion,which combines the detectable velocity percent with the effective system cycle determined by the improvement factor loss,is presented.The GMTI (Ground Moving Target Indication)performances of the classical formations,such as the Cartwheel,Pendulum,SAR-Train and so on,are evaluated by the presented criterion.Genetic algorithm is used to optimize the formation,with the satellite orbital parameters as the design variables.Simulation results demonstrate the validity of the evaluation function and the optimization algorithm.At last,the formation restriction was established according to the orbital perturbation theory and the cross-track baseline limition for GMTI performance.The optimal formation satisfying the close flying control theory and the GMTI requirement is presented.关键词：distributed small satellites;ground moving target indication;formation optimization;genetic algorithm;orbital perturbatio2|765|3更新时间：2025-07-16
- 摘要：The statistical models of SAR image with and without jamming noise and the statistical relationship between these images are presented to give a quantitative analysis on Information measure of SAR image and its Information loss caused by noise jamming.Thereby,an index based on the rate of information loss of SAR image is defined to make a synthetically quantitative description on the effect of SAR jamming.关键词：SAR;noise jamming;effectiveness evaluation;information of image;information loss2|1128|5更新时间：2025-07-16
- 摘要：According to the fact that the fourth-order cumulant of the Gaussian White Noise is equal to zero,the fourth-order cumulant of the DSSS/QPSK signal is studied and the time domain and frequency domain detection methods based on the fourth-order cumulant different slices c4x(0,0,0)、c4x(τ,τ,τ)、c4x(0,τ,τ) and c4x(0,0,τ) are proposed.Experimental results show that the detection performance of the method in frequency domain is better than that of the method in time domain.Trading off the detection performance and realization difficulty,the frequency domain detection method based on c4x(0,0,τ) is the best.When the false alarm probability is set to 1%,its detection probability reaches above 50% at SNR -11dB.The proposed methods don’t involve extensive matrix operations,their computation complexities are low,and they are easy to implement.关键词：fourth-order cumulant;direct sequence spread spectrum;signal detection;detection without codes2|1461|15更新时间：2025-07-16
- 摘要：To resolve the channel resources waste problem of current source-specific multicast (SSM) routing algorithm in low earth orbit (LEO) satellite IP networks,a new SSM algorithm called core-cluster-based source-specific multicast (CSSM) algorithm and its improved one (the weighted CSSM algorithm) are presented.The CSSM algorithm takes source node as initial core-cluster,and extends it step by step to construct entire multicast tree with the lowest tree cost by a shortest path scheme between newly-generated core-cluster and surplus group member nodes,which can greatly improve transport bandwidth utilization and transport efficiency.In the w-CSSM algorithm,end-to-end propagation delay can be decreased and meanwhile tree cost will be increased a bit by adaptively adjusting the weighted coefficient to meet strict end-to-end delay requirements of some real-time multicast applications.Finally,performance comparison of the two algorithms with the typical SSM algorithm (i.e.MRA) in LEO satellite networks is provided.Simulation results show that their tree cost performance is greatly better than that of MRA at the expense of a bit higher end-to-end propagation delay.关键词：satellite IP networks;LEO;routing;multicast;source-specific multicast (SSM)2|891|0更新时间：2025-07-16
- 摘要：For obtaining the electromagnetic scattering characteristic of a complex target efficiently,GRECO (Graphical Electromagnetic COmputing) is implemented by a programmable pipeline of a modern GPU (Graphics Processing Unit).The speed of the simulation can be improved up to 20 times compared with the raw GRECO.The ray tracing algorithm based on a GPU is implemented to obtain the multiple reflection contribution of a target with concave structure.This approach will redound to research works such as radar target identification and inverse synthetic aperture radar (ISAR) imaging.关键词：electromagnetic scattering;graphical electromagnetic computing;graphics process unit(GPU)2|2001|5更新时间：2025-07-16
- 摘要：Using the technology of substrate integrated waveguide,we designed two multi-way microwave power dividers with alternating output phases.Adjustments of the inductive metallic vias resulted in the 180-degree phase difference between adjacent output ports.Good agreements between the experimental results and simulated data prove that the proposed power dividers are of high performance.关键词：substrate integrated waveguide;power divide;alternating phase2|1778|4更新时间：2025-07-16
- 摘要：A domain decomposition method (DDM) based on the generalized variational principle is presented for the analysis of electromagnetic scattering problems.The original computation domain is partitioned into nonoverlapping subdomains.Then the modified functional for the original problem was established with help of Lagrange multipliers,which also enforce the continuity conditions at the interface nodes between neighboring subdomains.The method leads to a reduced linear system of equations where only the Lagrange multipliers occur.The invertibility of the coefficient matrix on each subdomain is studied.To improve the algorithm further,the restarted generalized minimum residual method (GRMES) is used as the solver because of its superlinear convergence behavior.The proposed method is very efficient,in particular for the electrically large problems.The validity and computational efficiency have been verified by some numerical examples.关键词：electromagnetic scattering;domain decomposition method;Lagrange multipliers2|655|3更新时间：2025-07-16
- 摘要：In calculating poles by theory,the method of moments (MoM) combined with contour integration is a common and smart one.Because of time consuming,it is usually used for the rotationally symmetric objects.In this paper,we approximate the Green’s function by Chebyshev polynomials.So,the factor of frequency can be extracted from electric field integral equation,which will largely decrease computation time in MoM at different frequencies.Then,it is possible to calculate targets’ poles of arbitrary shaped objects.Lastly,by the improved contour integration,three targets’ poles are calculated.关键词：method of moments;contour integration;radar target poles;Chebyshev approximation2|636|1更新时间：2025-07-16
- 摘要：The quantum sequential multi-signature scheme is researched first.The proposed scheme refers the model of the classical sequential multi-signature,employs quantum entanglement swapping to implement the message signature and its authentication as well as relies on quantum key distribution and one-time pad algorithm to guarantee perfect security.The proposed scheme supports infinite amounts of signatories,in addition,it chooses Bell-state photons as the information carrier,which means fewer photons are need to sign one bit message and be easier to realize.关键词：quantum cryptography;digital multi-signature;sequential2|666|13更新时间：2025-07-16
- 摘要：The paper presents an improved receiver clock bias forecast model.The model built with "coasting window" method,holds the real-time refresh parameters.The extrapolated future clock bias is used to augment RAIM performance.Relevant flow charts and a new algorithm for forecasting error are introduced.The data analysis proves that this method not only increases availability of RAIM,but improves the rates of fault detection and identification.The minimum fault that can be detected decreases from 50 meters to 40 meters;and the minimum fault that can be detected and identified completely dropped from 70 meters to 60 meters.关键词：integrity;RAIM;clock bias model;coasting window2|1199|12更新时间：2025-07-16
- 摘要：We present a FRFT high-resolution computation (zoom-FRFT) method,which can zoom-in on any interested portion of fractional spectrum by setting spectrum range and output number M.In addition,for solving lower efficiency of zoom-FRFT for small M,a FRFT single-point fast computation (SP-FRFT) method based on Horner rule is presented and its further reduction is made for zero-point computation.It can be used to increase computational efficiency for small M,and compute un-uniform output samples.Finally,two methods are verified by the simulations.关键词：fractional Fourier transform(FRFT);decomposition-type algorithm;high-resolution computation;single-point fast computation2|2101|17更新时间：2025-07-16
- 摘要：Starting with the relationship between the fractional Fourier transform and the time-frequency distribution,we derives the approximate expression of the fractional Fourier spectrum intensity of a single chirp based on the digital computation of the fractional Fourier transform.The shading between the fractional Fourier spectra of two chirps with different chirp rates is analyzed,and a formula is obtained,which is illuminated by some figures and verified by a simulation.We find that the amplitude,chirp-rate and sampling interval determine the shading between the fractional Fourier spectra of multicomponent chirp signals.Prolonging the sampling interval can reduce the shading when amplitude and chirp-rate of multicomponent chirp signals are determined.关键词：fractional Fourier transform;chirp signal;signal detection2|947|17更新时间：2025-07-16
- 摘要：We propose a new companding scheme to reduce Peak-to-Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) signals to revise our previous work,which is based on our rigorous theoretical derivation.Both theoretical analysis and simulation results show that the proposed companding transform can reduce PAPR to below 7.8dB while keeping the average power unchanged,and the system having good BER performance simultaneously.关键词：Orthogonal frequency division multiplexing;peak-to-average power ratio;companding transform2|1187|3更新时间：2025-07-16
- 摘要：It is difficult to obtain the ML(Maximum Likelihood) parameter estimation of GTD (Geometric Theory of Diffraction) scattering center model because we must solve a high-dimensional,nonlinearity,mixed-parameter optimization problem.A CPSO (Cooperative Particle Swarm Optimization) based algorithm is developed for obtaining the ML estimation of GTD model parameter.This method can obtain the amplitude,type and position parameter simultaneously,and it is insensitive to the initialization value.Comparing with RELAX-based method,the CPSO-algorithm need not iterative estimate repeatedly,so reduces the complexity of computation.The simulation tests show that the CPSO-based method can get quite accurate estimation result of GTD model.关键词：GTD(Geometric Theory of Diffraction) model;parameter estimation;cooperative particle swarm optimization2|625|8更新时间：2025-07-16
- 摘要：A OFDM scheme is proposed in this paper,which features the advantages of the two types of OFDM.It is capable of benefiting from both pulse shaping technique and guard interval.We examine the relation between pulse shaping filter and intercarrier interference in presence of frequency offset.Finally we introduce an example design and carry out simulations on it.Both numerical analysis and experimental results indicate that the design notably suppresses the interference between subcarriers.关键词：OFDM(Orthogonal Frequency Division Multiplexing);pulse shaping;guard interval;frequency offset;intercarrier interference2|1968|0更新时间：2025-07-16
- 摘要：Considering the characteristic of fast-moving inmobile ad hoc networks (MANETs) ,a virtual backbone network with a independent dominating set was constructed.This method can avoid sustaining connectivity between backbone nodes and the backbone network can be rapidly reconstructed as topology change.The minimal independent dominating set was settled by calculating maximal independent set,and with the set the algorithm and mathematical model of a virtual backbone network were provided.The result shows that the algorithm bears efficiency,low complexity and self-recovering ability.关键词：mobile ad hoc networks;virtual backbone network;backbone nodes;maximal independent set;minimal independent dominating set2|1097|5更新时间：2025-07-16
- 摘要：With the rapid development of ICT technologies,the distribution,copying,and editing the digital media content is more and more easy.The copyright management and content protection of digital content may decrease the content piracy and abnormal usage.In this paper,the basic principal of DRM (digital rights management) is introduced firstly.The key technologies of DRM are summarized in detail secondly.The DRM applications of main scenarios are analyzed thirdly.In addition,several challengeable problems are discussed.Finally,the key research interest and development tendency are expected.关键词：digital content;content security;digital rights management;standardization2|6040|19更新时间：2025-07-16
- 摘要：A synchronous acquisition scheme is presented for DS-UWB receiver in the presence of multiuser and indoor multipath channel environment.It utilizes the delay spread characteristics of the dense multipath channel when the impulse radio signals pass through the channel,introduces the adaptation equalization algorithm with random training sequence,and searches the major energy region using variable synchronous step length and MMSE criteria.The characteristics of the algorithm are analyzed on theories and simulations,which show the scheme realizes the quick synchronization in indoor environment.关键词：carrier-free UWB;multiuser receiver;synchronization;adaptation2|755|3更新时间：2025-07-16
- 摘要：Spurious peaks,extracting loss and doppler-coupling shift usually effect the application of the linearly modulated stepped frequency (LMSF) greatly.The mechanism of the still and moving spurious emergence in traditional target extracting algorithm is analyzed in the paper,which also presents the conditions for avoiding the appearance of the two kinds of spurious peaks.In order to lower the extracting loss,the paper describes a shift-extracting algorithm,which based on searching the maximum norm 1 of the range profile extracted by different shift quantity to fix on the optimum shift quantity,and then the final range profile can be obtained with the optimum shift quantity.Accordingly the moving spurious and extracting loss can be avoided,at the same time the doppler-coupling shift of the range profile is corrected.Moreover the paper analyses the application condition of this searching algorithm,and gives the design method for system parameters.The simulations on the point target and extended target testify the feasibility of the algorithm.关键词：linearly modulated stepped frequency;moving target;target extract;spurious peak2|656|6更新时间：2025-07-16
- 摘要：When inverse synthetic aperture radar (ISAR) imaging the target with complex motion,the time-varying rotation vector will induce phase errors depending on the scatter positions.Such errors can not be eliminated by traditional motion compensation algorithm,and the radar images obtained by the conventional range Doppler (RD) algorithm will smear.The intrinsic image-smearing reasons are analyzed when the rotation vector varies with time,and the radar received signal expression in presence of three dimension rotation is determined.An ISAR imaging algorithm based on the property of the scatter signals is proposed for the complex motion targets.This algorithm is effective for imaging the target which has constant rotation orientation but time-varying rotation velocity.Furthermore,when the rotation orientation varies slowly,the algorithm can also effectively improve the quality of ISAR images.Finally,several simulation results demonstrate the performance of the algorithm.关键词：ISAR;three dimensional rotation;imaging algorithm;discrete chirp-Fourier transform2|655|4更新时间：2025-07-16
- 摘要：Range-Gate-Pull-Off (RGPO) is a common type of electronic countermeasure (ECM) technique used to defeat or degrade tracking radars.The RGPO goal is to generate an ECM pulse that is a replica of the radar transmitted pulse with delay and amplification so as to pull the radar range gate off the target.Although a chi-square test algorithm for rejecting RGPO false targets has been proposed,it has low RGPO discrimination ratio and more error decisions in the absence of RGPO.To overcome its shortcomings,a new algorithm named as Chi + SLR + register is presented,which integrates the chi-square algorithm with a shift register and a signal likelihood ratio (SLR) test.This new algorithm has minimum probability of error decisions in specific length of shift register,and better performance than other algorithms in wide scope length of shift register.Additionally,the new algorithm is also effective in SOJ environment.关键词：range gate pull off(RGPO);RGPO discrimination;ECCM;SOJ;target tracking2|1158|11更新时间：2025-07-16
- 摘要：Three-dimensional radial magnetic flux leakage information around wire rope surface is acquired by Hall sensor array annularly distributed around the rope.An adaptive spatial notch filter is designed to eliminate the strand-waveform noise.Then the filtered signal is normalized and transformed to a gray-scale map.An image recognition algorithm is introduced to extract features from the gray-scale map and distinguish among several typical localized flaws.The results show the method can identify the degree and width of a defect,distinguish the circumferential distribution of defects,e.g.concentrated or dispersive breaks.关键词：wire rope;localized flaw;quantitative testing;Hall sensor array2|1115|4更新时间：2025-07-16
- 摘要：In the received bandwidth,there exist several subband signals with nonuniform distributions and different bandwidths,whose number,bandwidths and locations are unknown and time-variant.A method of dynamic channelization is proposed.Channel number of modulated filter bank is determined by the minimal guard bandwidth among the signals,and then a prototype filter that meet the need of Near-Perfect-Reconstruction (NPR) is designed to construct an analysis filter bank.Second,location of signal is attained by the use of energy detection of every channel,and the corresponding synthesis filter bank is designed to extract desired signal.When dynamic channelization takes place,location of new signal is attained through updating energy detection,and then the corresponding synthesis filter bank can be derived to channelize new signal without changing analysis filter bank.Theory analysis and computer simulation verify the feasibility of the new method.关键词：modulated filter banks;Near-Perfect-Reconstruction(NPR);polyphase decomposition;channelization;wideband receiver2|1097|7更新时间：2025-07-16
- 摘要：This paper proposes a layout-level synthesis based frequency partial-space-mapped neuromodeling technique (FPSMN) for RF circuit.We exploit space-mapping technique to simplify the relation between the neural network (NN) training data and teaching data and therefore to reduce the cost for training in neuromdoeling.FPSMN establishes a partial mapping for the physical parameters,making even more efficient use of the implicit knowledge in the coarse model.This allows us a significant reduction in NN complexity and in training time.The coarse model is obtained from layout-level synthesis.Lumped-circuit modeling based on electromagnetic (EM) simulation describes the important parameters and parasitic parameters.It can serve as high quality coarse model in FPSMN.A Stoer-Bulirsch adaptive frequency sampling (S-B AFS) technique is used to decrease the cost for frequency sweeps. Numerical results of a low temperature cofired ceramic (LTCC) bandpass filter illustrate the advantage of the proposed method over existing techniques.关键词：synthesis;frequency partial-space-mapped neuromodeling (FPSMN);neural network (NN);S-B adaptive frequency sampling (S-B AFS);low-temperature cofired ceramic (LTCC)2|1129|5更新时间：2025-07-16
- 摘要：An algorithm with the ability of track quality control is proposed for tracking multi-target in clutter based on the T-RN multi-static radar system,and the information of signal amplitude is used in the algorithm.Then,quantitative analysis is carried out in two ways:the probability of correct test at the track’s initializing time and the average sample length.These two parameters are used to represent the improvement of the performance of track test.Simulation results indicate that this algorithm can steadily track multiple targets.关键词：multi-static radar;multi-targets tracking;information fuse;date association;signal amplitude2|1076|3更新时间：2025-07-16
- 摘要：In order to resolve conflict of measuring speed and precision,a novel measurement was proposed to detect approximate defect positions by image recognition and to measure accurately the three-dimension profile by laser displacement sensor.The image capture and data acquisition equipment for scanning measure was designed for spherical surface.The image background noises were reduced by low-pass filtering algorithm based on analyzing image features.According to the difference between high and low envelope curve constructed by maxima and minima on the current processing image,the approximate defect positions and region were determined.The defect edge was approached iteratively based on Snake model.The data processing and defect representations of the three-dimension profile were discussed.This method outperforms traditional image segment methods at self-adaptation to complicated background images.Moreover,the measuring system can measure automatically and reliably to detect surface defects.关键词：surface defect;measurement method;image recognition;data processing4|859|0更新时间：2025-07-16
- 摘要：This paper studies the 3-dimension active deception jamming instead of the 2-dimension active deception jamming which is invalid for interferometric SAR (InSAR).The 3-dimension active deception jamming need two or more jammers,comparing to that the 2-dimension active deception jamming need only one jammer.This paper studies the error of the 3-dimension active deception jamming.This paper also studies the problem of how to deal with the edge of the active deception jamming image.It is a preferable method to blot out the edge of the images.It can deal with the problem of smooth join of the deception image and the real image.2|581|9更新时间：2025-07-16
- 摘要：An optimal scheme is provided for the detection of moving objects observed in airborne SAR(Synthetic Aperture Radar) image.Along cross-range direction,the image data pass through a band-pass filter aiming at the frequency spectrum of the moving target and is corrected by subtracting the moving target quadratic phase error.Then,the same data pass through a band-pass filter aiming at the mirror frequency spectrum of the moving target and is corrected by adding the same quadratic phase.Both results are projected to time axis,and the moving target is detected by subtracting the two images’ energy.Combined with genetic algorithm,the effective parameter estimation and high detection speed are achieved.The experimental results verify the effectiveness of the method.关键词：synthetic aperture radar;moving target detection;genetic algorithm2|605|1更新时间：2025-07-16
- 摘要：Detection performance of linear frequency modulated signal is analyzed in theory according to Wigner-Hough transform and generalized likelihood ratio test (GLRT) theory when two detection thresholds are set,and expressions for the probability of false alarm (PF) and the probability of detection (PD),as a function of the number of accessible Hough space accumulator cells and detection threshold.Then probability density function is approximated rationally and the calculation of the number of accessible Hough space accumulator cells is derived.Finally comparison of detection performance of based on Fourier transform and based on Wigner-Hough transform is made,and comparison of detection performance of different Swerling fluctuating targets is made also.关键词：linear frequency modulated signal;detection performance;Wigner-Hough transform2|1509|17更新时间：2025-07-16
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