最新刊期
卷 29 ， 期 9 ， 2001
- 摘要：This paper is the second paper about the theory and application of amplitude non-uniformly sampled signals.In this paper,at first we analyze the effect of the offset error in paper [1] on the input signal's spectra,then explain the principle of increasing the amplitude resolution,and derive the additional signal spectra representation with sinusoid input.We present two methods to improve the system amplitude resolution.At last,computer simulation to obtain the relation curve between the system ENOB and the input signal's frequency is given.关键词：offset error;amplitude resolution;signal-to-noise ratio2|790|1更新时间：2025-07-16
- 摘要：A filter bank design based on orthonormal wavelets and equipped with a multiscale Kalman filter was recently proposed for estimating fractal Brownian motion in additive Gaussian white noise.In this paper,we give the corresponding parameters of the dynamic system and more accurate estimation algorithm.Comparisons between Wiener and Kalman filters are given.Typical computer simulation results demonstrate its feasibility and effectiveness.关键词：fractal stochastic signal;fractional Brownian motion;1/f processes;Kalman filtering;wavelet transform3|979|1更新时间：2025-07-16
- 摘要：Based on the minimum mean-square error,this paper offers an optimum threshold method of estimating the 1/f-type fractal signals with the additive white noise.The paper also provides the method of determining the wavelet decomposition scale.Compared with the multiscale Wiener filter,the optimum threshold method is more practical and maneuverable because it doesn't estimate the variance of 1/f-type fractal signals and the wavelet decomposition scale can be determined in advance.关键词：fractal signal;fractional Brownian motion;1/f processes;signal estimation;wavelet transform2|836|2更新时间：2025-07-16
- 摘要：A fast and accurate estimation technique of frequency and initial phase of single-tone signal based on the phase of the DFT spectrum is proposed.To eliminate the ambiguity in DFT phase measurement,the sampled data are divided into two segments and the DFT is applied on them individually,then the frequency and initial phase of the signal are estimated with the phase difference of the two DFT spectra at their maximum amplitude position.Computer simulation results show that the variance of frequency estimation is close to the Cramer-Rao bound,and the SNR threshold is much lower than that of the ML estimators for moderate N (length of DFT).For SNR=6dB and N=1024,the RMS error of frequency estimation is about 1% of the frequency resolution of the DFT,and the RMS error of the initial phase estimation is about 2 degrees.Formulas for evaluating the RMS errors of frequency and phase estimation in white Gaussian noise for different SNR and N are also presented,which fit well with computer simulation results.This technique has been used in FMCW level radar and 1mm range measurement accuracy has been achieved.关键词：frequency estimation;phase estimation;microwave ranging;DFT2|3020|58更新时间：2025-07-16
- 摘要：A novel digital phase-tracking and measuring loop(DPTML) appropriate for distance measurement are proposed and analyzed using the theory of finite Markov chains.The performance of steady-state phase-tracking error and phase acquisition time in the presence of additive band-limited white Gaussian noise are evaluated.By analysis of the noise-resistant characteristic of the key module,guidelines on selection of its pivotal parameter are given.A new method utilizing the acquired steady-state results to ulteriorly reduce the tracking error is also presented.Both the calculated and simulated results indicate that the DPTML has much less steady-state error than traditional zero-crossing digital phase-locking loop(ZC-DPLL).Additionally,because the "hangup" effect leading to prolonged phase transients owing to the presence of the dead zone around π rad is thoroughly eliminated,the phase acquisition time of the DPTML is much shorter than the latter,especially in high SNR.关键词：distance measurement;phase measurement;Markov chains;hangup;signal to noise ratio(SNR)2|803|0更新时间：2025-07-16
- 摘要：In the process of ATT,the small tracing window often doesn't satisfy the demand of system reliablity because the tracing platform is usually unstable.A fast searching approach of the center of gravity based on Log-polar Coordinate mapping is presented in this paper.The result of experiment shows that the tracking speed of system is still fast even the tracking window is bigger,and the stability of tracking system is greatly enhanced.关键词：ATT;Log-Polar Coordinate mapping;searching the center of gravity3|1251|5更新时间：2025-07-16
- 摘要：Basing on subspace principle,the paper provides a calibration approach for mutual coupling among sensors of uniformly spaced linear arrays or circular arrays.The benefit of this new method is that only one calibration signal is needed,whose angle may be unknown.The computer simulation results demonstrate that this approach is correct and effective.关键词：array signal processing;subspace principle;mutual coupling;error calibration2|972|6更新时间：2025-07-16
- 摘要：Based on the MUSIC and ESPRIT techniques and using the signal temporal information,a new method with high precision is presented for simultaneous estimation of frequency and direction of arrival (DOA) of spatial coherent signal sources over a wide frequency band. By means of forming a so-called smoothed DOA matrix,the estimated parameters of frequencies and DOAs are paired automatically.Simulation results show that the proposed method is effective.关键词：DOA estimation;frequency estimation;smoothed DOA matrix3|1033|6更新时间：2025-07-16
- 摘要：This paper describes a new method which uses IDFT (Inverse Discrete Fourier Transform) technique to do time-domain near-field measurement for antenna.According to Fourier Transform Theory,the feasibility of this method is demonstrated in this paper.Some calculation examples show that this method is effective and exact.The errors led by this method are analyzed and the principles for deciding the key parameters in using this method are given,the test results are discussed and the conclusions are reached.关键词：IDFT;antenna measurement;time-domain near-field test2|2094|3更新时间：2025-07-16
- 摘要：A vanishing point or a vanishing line indicates the direction information of a set of parallel lines or a set of parallel planes.The vanishing points of all lines in the same plane are colinear at the vanishing line of the plane.The cross ratio of four points in the vanishing line is a projective invariant.It is related inherently with the intersection angles among the lines that the vanishing points correspond.So,this paper presents an approach based on the projective invariants of vanishing points to calculate the intersection angles of planar lines.Without any calibration or 3D reconstruction,the approach can be used to describe the relationship between planar lines,such as parallelism,perpendicularity or intersection,and so on.Our method is applied to some real images for interpreting the relationship of lines,and the experimental results verify its efficacy.关键词：projective geometry;infinite element;vanishing point;vanishing line;cross ratio;projective invariance4|1715|7更新时间：2025-07-16
- 摘要：In this paper,we show that the performance of conventional Decision Feedback Equalizer (DFE) followed by Viterbi decoding for coded Inter-Symbol Interference (ISI) channels may be improved significantly by iterative use of decoding information.At each iteration,DFE may outperform its original form since now feedback decisions are more reliable as some errors are corrected by Viterbi decoding.The proposed algorithms may find some practical applications since they have relatively low complexity.关键词：DFE;ISI;Turbo principle2|900|0更新时间：2025-07-16
- 摘要：Because dithering exists inevitably while missile flying,there are heavy difficulties in information processing at low SNR.Therefore,the paper presents a new method for tracking data processing in image under dithering.The method can locate the targets effectively,so it is possible for dithering image processing without stabilizing images.It can greatly reduce the system's designing costs and shorten the designing period.关键词：dithering;data processing;target tracking;stabilizing image2|884|0更新时间：2025-07-16
- 摘要：The method of moments (MOM) in conjunction with the asymptotic waveform evaluation (AWE) technique is applied to predict the mono-static radar cross section (RCS) pattern of an arbitrarily shaped two-dimensional (2-D) perfect electric conductor (PEC) body.The electric field integral equation (EFIE) of a 2-D PEC body irradiated at a given direction by radar electromagnetic (EM) wave is solved using MOM to obtain the low order moments of the surface current on the PEC body.In the AWE technique,the surface current is obtained at any angle within the angular range expressed as a rational function,which is in turn used to calculate RCS of the 2-D PEC body.It was observed that AWE could result in considerable CPU time saving.关键词：Mom;AWE technique;RCS;2-D PEC2|943|7更新时间：2025-07-16
- 摘要：Spaceborne synthetic aperture radar (SAR) image simulation methods are investigated in this paper.A new method is proposed based on fractal theory,facet model and clutter scattering characteristic model.Digital elevation model of a natural terrain is used in computer simulation.The simulation results demonstrate that the stochastic properties and special geometric distortion phenomena of natural ground scene spaceborne SAR image are reflected in the simulated images.The simulation method is suitable for verification of SAR satellite system scenario,and it has significant importance to realize the optimization of system scenario of SAR satellite.关键词：spaceborne synthetic aperture radar;fractal;facet model;radar scattering model2|1145|21更新时间：2025-07-16
- 摘要：In traditional tracking radars,the joint parameter estimator that is constructed as the Doppler filter bank is optimum in the sense of maximum likelihood,whereas such estimator bears the shortcomings of the considerable complexity in implementation and the loss of detectability in dense target environment.Based on the designing of sub-optimum nonlinear frequency modulated signal,a novel structure that has only two NLFM channels is described,with the performance analysis and the simulation results also presented.关键词：pulse compression;tracking radars;nonlinear frequency modulation;bi-channel estimator2|1716|0更新时间：2025-07-16
- 摘要：Rail-UWB-SAR system has such merits as controllable,repeatable,and low-cost,and is an effective means to study UWB SAR.A new experiment method to solve LFM radar range `dead' area,bistatic SAR,was presented in the paper.The bistatic SAR imaging algorithm was studied.The feasibility of the experiment method was confirmed by experiment results.The accuracy of Rail system was analyzed.Lastly,the disadvantage and its application were discussed.2|794|5更新时间：2025-07-16
- 摘要：Some improvements to BeiDou Satellite Navigation System are shown in this paper.With these improvements,it can work as a no-node,real-time and one-way positioning system.These improvements have been simulated by computer,and the improvements are obvious.关键词：navigation;computer simulation2|1296|11更新时间：2025-07-16
- 摘要：This paper devised a new method of close-loop rectification for integrated navigation system,which has been the important developing direction of the navigation technique at present.This method realizes close-loop rectification by using the accumulated error to compensate the output of the subsystems.Taking the INS/GPS integrated system as example,the paper illustrates the practicable algorithm,and provides the result of computer simulation.The method has the advantages of the open-loop and close-loop rectifications,and can be used in various navigation systems which use indirect-filter-positioning method by the measurement of pseudo-range.As a result,the method has extraordinary practical value in the technique developed for the integrated navigation systems.2|1089|3更新时间：2025-07-16
- 摘要：A new filtering Algorithm based on information fusion is presented in this paper in view of the research on integrated navigation system.This method overcomes the demerit of the same mathematical model in local and global filter,therefore improves the versatility of the system.The authors analyze the basic concept,model establishment and frame of the integrated navigation system in detail,then give the computer simulation for GPS/INS.The results show this method is very useful because it can improve the accuracy and calculation speed of the system.关键词：Information fusion;Kalman filter;integrated navigation2|1007|5更新时间：2025-07-16
- 摘要：The article studies a method of raising directional precision by amplitude shading in sensor array's directivity design.Synthesized patterns with different restricted conditions can efficiently abase the width of beam on definite minor lobe levels,using multi-level Chebyshev weights on equidistant linear array.关键词：sensor array;multi-level amplitude shading;directivity synthesis4|880|0更新时间：2025-07-16
- 摘要：Compared with the conventional filter structure,the parallel filter has higher throughput rate and lower power consumption.In this paper,the principle of parallel adaptive 2-by-2 algorithm based filter is presented.The parallel LMS algorithm and its performances are discussed.Simulations verify the performance of our approaches.关键词：adaptive filter;parallel LMS algorithm;performance analysis2|1143|3更新时间：2025-07-16
- 摘要：A planar feeding circuit is proposed in this paper,which is structured by co-planar waveguide and excites a rotating mode in parallel plate waveguide.A CA-RLSA fed by this circuit has a foresite beam.The structure is planar and available to integration and minimization even in millimeter wave band.It is also suitable to excite a CA-RLSA with a conical beam if parameters are properly changed.It is proved by the simulation and experiments that the mechanism and principle are reasonable.关键词：feeding circuit;CA-RLSA;CPW;ring slot;cavity2|1131|0更新时间：2025-07-16
- 摘要：The design and implementation of the digital baseband part of a DAB transmitter prototype are introduced.It is composed of ensemble multiplexer,channel encoder and OFDM modulator.The equipment is totally compatible with ETS 300 401 and other related standards.It supports services with various data formats and supplies a convenient user interface with the ensemble multiplexer as well.All of its I/Os and the core parts are implemented using modular design based on universal internal interface,thus can be flexibly configured according to different demand.Compared with the existing products,it can provide higher flexibility and operating easiness on a much lower cost level.关键词：DAB;transmitter;multiplexer;COFDM encoder2|936|0更新时间：2025-07-16
- 摘要：The paper discusses a direct analytic solution of multisensor data fusion to avoid multiple iterative calculation of nonlinear differential equation,and the calculation amount is reduced,thus it raises solution efficiency of multisensor data fusion.The paper discusses performance control technique of sensor to ensure confidence and safety of multisensor data fusion.To raise detection capability of multisensor network for stealthy target,low-altitude flying target and target in jamming environment,the paper discusses multisensor adaptive detection fusion technique.The paper also analyses several advantages of sequential fusion for mobile target.关键词：data fusion;state fusion;adaptive detection2|2211|4更新时间：2025-07-16
- 摘要：This paper analyses the error correcting code performance in the AGWN channel,then deduces the code gain of RS code,and the error correcting capability of the combination of RS code and interleave.This paper also analyses the improvement of TCM-8VSB relative to 4VSB,and draws the conclusion that the parameters in ATSC channel code standard are optimal.2|989|0更新时间：2025-07-16
- 摘要：A fuzzy sets method for classification of arrhythmias is developed in this work.At first R-R and QRS interval are transformed into fuzzy variables with S-style and Z-style membership functions.Then their grades of membership for normal and beats of PVC and APC are calculated to determine the classification.The method is verified with MIT-BIH database and the clinical data.The results show that this method is effective for the classification of arrhythmias accurately and rapidly.关键词：ECG;fuzzy sets;arrhythmias classification2|1015|8更新时间：2025-07-16
- 摘要：This paper studies the detection method of hovering helicopter with phased array airborne early warning(AEW) radar.The approach to detect the flash echo-signal from blades of a hovering helicopter is proposed,which is used by the Multi-Doppler-Channel Joint(MCL) detection and Time-Space Cascaded Adaptive(TSA) processing to suppress clutter.The configuration of detector is given,the performance of the detector is analyzed,and the feasibility and effectiveness are verified with Monte Carlo test.关键词：hovering helicopter;airborne early warning radar;signal detection3|1332|2更新时间：2025-07-16
- 摘要：The characteristics of ADC quantization nonlinearity under a signal in colored noise are analyzed.Analytic method and theoretical explanation are given.Our research shows that ADC quantization,under the condition of low SNR,has its own regulation.Using the test method presented by this paper,test result of accumulation can correspond to any tidy change of input signal.So we can get higher resolution based on primary high resolution ADC.We also can improve the system design of weak signal detection.At last,we point out that it's necessary to test the characteristics of ADC quantization nonlinearity under the condition of low SNR for engineering application.关键词：ADC;quantization nonlinearity;data-acquisition2|740|1更新时间：2025-07-16
- 摘要：Based on impulse response of modes in a uniform waveguide,a modal absorbing boundary condition,employed in finite difference-time-domain(FDTD) method,is specially calculated and investigated in this paper.The high order interpolated method is used to significantly improve the accuracy of modal absorbing boundary condition,and computing speed is accelerated by applying point matched method to identify the amplitude of modes.The numerical simulation shows that the number of nodes of FDTD can be dramatically reduced by applying the modal absorbing boundary condition that leads to the improvement of the efficiency of FDTD method.关键词：modal absorbing boundary condition;impulse response;FDTD method;waveguide2|1216|2更新时间：2025-07-16
- 摘要：A fast skeletonization algorithm directly for gray-scale patterns is presented in this paper by simulating the procedure of water scouring the image surfaces.It is shown that this algorithm can produce connected and one-pixel-wide skeletons which are invariant to the strictly monotonic transformations of the original images and also keep the topological properties of the original image unchanged and lie in the middle lines of the patterns.The experiments on the binary images and the gray-scale images show the efficiency of the algorithm.关键词：watershed transformation;skeletonization;ridge point2|1055|3更新时间：2025-07-16
- 摘要：The Domain Decomposition Method (DDM) in conjunction with the asymptotic waveform evaluation (AWE) technique is applied to obtain the radar cross-section (RCS) of a 3-D cylinder over a frequency band.The equivalent electric current and magnetic current on the surface of the cylinder are firstly expanded in Taylor’s series over a given frequency and solved by FDFD-DDM.Then the Taylor’s series are converted to rational functions via Padè approximation and the surface equivalent electric current and magnetic current can be achieved at any frequency within a desired frequency band,which are used to calculate the RCS of the cylinder.A good agreement between our results and the results from reference verifies the validity of this technique.In addition,the computational efficiency is considerably improved compared with the traditional FDFD-DDM.关键词：DDM;FDFD;AWE technique;RCS;3-D cylinder2|979|1更新时间：2025-07-16
- 摘要：Recent studies have shown that performance of DOA estimation via ESPRIT or other algorithms degrades drastically with a bad knowledge on array manifold.In this paper,a new approach based on subspace rotational invariance (SRI) for DOA estimation with unknown intensity coefficients is proposed.The ambiguous estimation appears in certain cases and must be eliminated.Detailed analysis of ambiguous problem is presented and is illuminated by numerical examples.关键词：unknown intensity;DOA estimation;SRI;ambiguity2|856|1更新时间：2025-07-16
- 摘要：Smart antenna and other spatial filtering technologies provide promising improvementation to the future wireless communication systems.The successful implement of these technologies demands detailed research and analysis of the temporal and angular characteristics of the wireless channels.This paper introduces some simulation work about the temporal and angular spread characteristics in typical microcell environment using ray tracing technique.The simulation results are divided into two parts:Line of Sight(LOS)'s and Non-line of Sight(NLOS)'s.According to the temporal research method,the author uses average angular spread and rms angular spread to describe the characteristics of angular spread.The detailed descriptions of angular spread in typical microcell environment are given finally.关键词：temporal spread;angular spread;ray tracing;dispersive channel;line of sight;non line of sight2|953|1更新时间：2025-07-16
- 摘要：Linear frequency-modulated pulse is one of the most important large time-bandwidth product signals,but it demands large amount of calculations for digital processing.In this paper,methods to improve parallelism of FFT calculation in VLIW architecture processor are studied,and a modified fixed-point FFT algorithm is promoted to meet the need of computation speed and accuracy,the calculation error of new algorithm also analyzed.Then a high-speed real-time digital pulse compression system based on TMS320C6201 is realized.It can implement DPC processing within 124us,which is very close to the top performance of TMS320C6201.The whole system has been applied in some radar and proved stable and reliable.关键词：linear frequency-modulated;digital pulse compression;FFT;VLIW;TMS320C62012|836|3更新时间：2025-07-16
- 摘要：As PLLs have some disadvantages such as the narrow synchronizing and pull-in ranges to smooth clocks with low-frequency large-amplitude jitter and wander,this paper presents a novel universal digital clock smoothness technique ─ the counting prognostication method.The key element of this technique is to use counting results in a cycle to prognosticate numbers in the next cycle.Principles and performance analyses are given to show that it can efficiently smooth jitter and wander,jitter accumulation is small,and the synchronizing and the pull-in range is very wide to smooth different frequencies.In addition,for applications in some special circumstances,the cycle varied counting prognostication method is also presented to diminish the capture time.关键词：clock smoothness techniques;jitter;wander;counting prognostication2|936|0更新时间：2025-07-16
- 摘要：In the paper,theoretical model of the effect of mutual coupling between antenna elements on the imaging of synthetic aperture radiometer (SARad) is established.The effect of mutual coupling on the resolution of SARad is analyzed.An analytical expression for the calibration of mutual coupling is presented.On the basis of theoretical results,a scheme for the calibration of SARad is proposed.Numerical simulations show the validity of the proposed method.关键词：interferometric synthetic aperture;microwave radiometer;mutual coupling;calibration2|1079|9更新时间：2025-07-16
- 摘要：The Fresnel zone theory is employed to determine the boundary to distinguish propagation regions for line-of sight topographies in tunnels.The formula for calculationg the break point distance is obtained.A hybrid propagation model combining the free space propagation model and the modified waveguide propagation model is proposed.The hybrid model and the break point distance formula are validated with our own and other published experimental data in various tunnels and at different frequencies.It is shown that the free space propagation model can be used to predict propagation loss in region prior to the break point ,while the modified waveguide propagation model offers excellent prediction of propagation loss after break point.关键词：radio propagation;personal microcellular radio communication;tunnel2|1158|9更新时间：2025-07-16
- 摘要：In this paper,a normalized band-limited Weierstrass fractal model is presented for modeling the time-varying rough sea surface.In particular,the Pierson-Moskowitz spectrum is incorporated into this model to represent a fully developed sea surface.The solution of the scattering field from this fractal surface is studied based on Kirchhoff theory,and the effect of the incident angle on the backscattering cross section is discussed.The relationship between the fractal dimension of the time series of the the backscattering cross section and the fractal dimension of the sea surface is given.The numerical results of the scattering fields show that the distribution of the scattering amplitude satisfies the K-distribution.关键词：fractal sea surface;Kirchhoff approximation;electromagnetic scattering2|1314|10更新时间：2025-07-16
- 摘要：A kind of fair round robin(FRR) scheduling algorithms ,which schedule the cell transmission slot in the schedule table by timestamps,are studied in this paper.The performance of three algorithms belonging to FRR are analyzed and compared.FRR can guarantee the bandwidth and delay of a connection ,and the implementation complexity of FRR is lower than some of packet fair queuing(PFQ) algorithms,such as WF2Q+.关键词：packet fair queuing;schedule table based round robin;fair round robin(FRR);shaped fair round robin(ShFRR)2|918|2更新时间：2025-07-16
- 摘要：The history of the development of the magic-T in MIC and MMIC is presented briefly,and the difficulty and disadvantage in analysis and design of such magic-T is pointed out.The principle of a model of a magic-T formed by microstriplines and slotlines is explained and detailed equivalent circuits as well as equations based on it are given.To design magic-T effectively,a new method which combine the method of equivalent circuit and FDTD to design magic-T is given.Then an example of designing a magic-T is showed and all process of designing the magic-T in such method is presented in details.This magic-T is similar to one reported by Mzsayishi Aikawa,but is made in MIC and its center frequency is 6GHz.It shows good performance between 3.3GHz to 9.9GHz.The reason for using full-wave analysis is presented.The perfectly matched layer (PML) and non-uniform meshing techniques are used for getting accurate results in analysis by FDTD method.关键词：FDTD;non-uniform orthogonal grid;magic-T2|913|0更新时间：2025-07-16
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