Search

Copyright of Transactions of Beijing Institute of Technology is the property of Beijing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The adaptive cancellation techniques of direct wave interference in passive bistatic pulse radar were developed in this paper. When the scatter signal was mixed with the direct wave, and can not be separated by the time window technique, a new variable-step-size normalized LMS (new VSSNLMS) algorithm was proposed to implement the adaptive cancellation of direct wave interference, on the basis of the analyses of the conventional LMS algorithm, normalized LMS algorithm, and variable-step-size LMS algorithm. The superiority of the algorithm was proved by the computer simulation. The proposed algorithm was applied to adaptive cancellation of direct wave interference in passive bistatic pulse radar. The theoretical analysis and simulation results show that a faster convergence rate as well as a smaller output error are obtained by the new VSSNLMS algorithm than the conventional LMS, NLMS, and MSVSLMS algorithm. [ABSTRACT FROM AUTHOR]

The location result of VTS radar station had an important influence on the normal functioning of the entire system. This paper put forward the bi-objective optimization model. The first function was to minimize the total cost including the cost of radar and the line laying cost between the radar station and the VTS center, and the second objective was to maximize the total weight of the multiple coverage units. In view of the model, a penalty function and an elite reserve strategy of genetic algorithm were designed. The example analysis results show that the solution can achieve universal coverage and focus on strengthening of water units. The location of VTS center and the radar blind area will affect the location of radar station. The program is run 10 times with stable calculation results, so the algorithm is convergent and stable, and the model is feasible. [ABSTRACT FROM AUTHOR]

In view of the limitation of the range factor on analyzing low probability of intercept (LPI) performance of MIMO radar systems, a performance parameter is derived and applied for quantifying the LPI performance of distributed MIMO radar systems. A series of contour charts have been given with different values of geometrical parameter. By plotting and analyzing these charts, the LPI performance can be obtained intuitively. Simulation results show that LPI performance of distributed MIMO radar systems depends on both radar parameter and system geometry. It is shown that the spatial diversity gain plays an important role in designing a distributed MIMO radar system with robust LPI performance. [ABSTRACT FROM AUTHOR]

In the framework of the shared-memory computer system, a hyhrid parallelization technique based on Open MP and VALU acceleration for the method of moments (MoM) solution of the surface integral equations (SIE) is proposed. In addition, several key issues in the hyhrid parallel MoM code design and the major factors influencing the parallel efficiency are addressed in detail. Numerical results of the radar cross section of typical objects show that load-balance and memory-read continuity are the key factors influencing the parallel efficiency. [ABSTRACT FROM AUTHOR]

Under the complex environment including both radar signals and communication signals, a signal modulation recognition proposed, based on pulse description word (PDW), realizes multiple signal separation using the ability of the digital channelized receiver to process simultaneous arrival signals. It can accomplish the modulation type recognition and the parameters extraction depending on instantaneous frequency analysis and wavelet transform analysis. The simulation test results demonstrate the effectiveness of this proposed method. [ABSTRACT FROM AUTHOR]

For multi-lane objects identification of vehicle adaptive cruise control, the coordinates of on car radar is transformed and invalid objects are discarded based on lane information. Radar objects were tracked by comparing the radar information of current sample period with the predicted value of previous period. Object identification process was accomplished by applying threshold, sliding sample window and nearest object selection in different phases of calculation. In the curve road, norm central angle method was adopted for position compensation. Experiments indicate that the identification of multi-lane objects and curve road compensation could be realized in a satisfied way and the requirements of ACC system could be fulfilled. [ABSTRACT FROM AUTHOR]

The application of dual-polarization microstrip array antenna in mono-pulse radar system is introduced. The radar system may achieve polarization diversity and multi-polarization angle error extraction abilities with this design. A mono-pulse antenna array is accomplished with two dual-polarization sub-arrays. Amplitude comparing angle error extraction method and polarization synthesize technique are absorbed to obtain sum and difference beam patterns and angle error curves in linear, circular and ellipse polarization waves. A low cost two dimensional mono-pulse antenna array is also represented. Both azimuth and pitch angle error extraction methods are introduced. The results show the feasibility of dual-polarization mono-pulse antenna based on stacked structure. [ABSTRACT FROM AUTHOR]

The bandwidth will get narrow when the size of HF antenna is small. To overcome this problem, a novel miniaturized HF antenna composed of hemispherical wire grids with performance similar to the electric dipole is presented in this paper. The antenna has simple structure and is easy to feed. The largest dimension of this antenna is 3. 6 m, which is 3. 6% of its lowest frequency wavelength, and 36% of its highest frequency wavelength. The antenna is simulated with the help of CST MWS. A 1/5 scale model is manufactured and measured. The results demonstrate that the relative impedance bandwidth is 40% without loading or external matching networks while maintaining acceptable performance. A method of broadening frequency range by loading lumped elements is further discussed, and simulation and test verification have been done. The designed antenna can be widely used in HF communication system, over-the-horizon radar and so on. [ABSTRACT FROM AUTHOR]

Under low signal noise ratio, estimation accuracy using classical algorithms, such as envelope-demodulation and instant autocorrelation spectrum, can't satisfy with the system requirements. To enhance the estimating accuracy of pulse repetition interval, pulse width and frequency modulation rate, an integrated method of multi-parameter estimation is proposed based on fractional Fourier transform (FRFT) in this paper. The focusing capability of FRFT was used for linear frequency modulation (LFM) signal and the relativity of estimation algorithm for each parameter was considered. Moreover, the founded test platform was utilized that transmits and receives LFM pulse compression radar signal to do a trial on algorithm. The results demonstrate its feasibility. The proposed method could not only get high estimation accuracy but also have good ability in real-time processing. [ABSTRACT FROM AUTHOR]

Conventional algorithms based on short-time Fourier transform time-frequency analysis can not extract the detailed micro Doppler features caused by motion of different parts of human leg and arm. The fractional Fourier transform (FRFT) is proposed and applied to extract the detail features of gait. The fractional Fourier transform spectrum generated from real measured data is presented and analyzed. Test results show that, by fractional Fourier transform, the detailed micro Doppler features of human limbs swing can be extracted from the experimental gait data. [ABSTRACT FROM AUTHOR]

In spaceborne SAR (Synthetic Aperture Radar) , the pulse compression of LFM (Linear Frequency Modulated) signal would be affected by the system phase error which changes in the space environment. Therefore a method of in-orbit phase pre-distortion for LFM signal based on polynomial fitting is put forward, in which the system phase error is obtained by in-orbit calibration, the phase compensation parameters are obtained by polynomial fitting on ground, and by uploading phase compensation parameters, LFM signal with compensation phase is generated by in-orbit calculation. The basis of the theory is described, as well as the realizing flow of the method is presented. Also, hardware requirements and advantages of the method are analyzed. The method is compared with other methods, and is verified to be efficient by the simulation and experiments in real system. [ABSTRACT FROM AUTHOR]

For a bistatic HF radar, the bistatic angle, ocean current and physiognomy of receiver location will bring about the Bragg lines' spreading, peak split and peak shift, so that the first order ocean clutter will be detected and tracked as a false target in some cases. To solve this problem, a fast method is proposed to suppress the ocean clutter. Based on some priori knowledge and stationary properties of the ocean surface, the ocean clutter frequency range to be suppressed was obtained on the Range-Doppler(RD) spectra. Then the Clean algorithm was applied to suppress the ocean clutter on the un-beam-formed channel data, after that the digital beam forming was performed and the obtained data were more helpful for target detection. The results show that this method is valid and can be implemented for real-time operation. [ABSTRACT FROM AUTHOR]

A novel digital radio frequency memory (DRFM) system used in repeater radar jammer was proposed. The principle of filter bank and the common structure of DRFM system were introduced. Considering the analysis and synthesis ability of filter bank, DRFM system based on filter bank was derived and designed. The proposed DRFM system has the advantages of broad band coverage and wide dynamic range. It also can realize perfectly the reconstruction of crosschannel signal in channelized reception. The repeater radar jammer with DRFM system have already been tested, which proved the property of this system. [ABSTRACT FROM AUTHOR]

In order to precisely calculate the clutter power of the radar seeker, this paper presents a new method of judging the ground clutter integration region of radar seeker. According to the geometric relationship between the iso-range lines and iso-Doppler, the shapes of integration regions, which are decided by distance and velocity gate under various sphere coordinates, can be partitioned. This method can precisely locate the ground clutter integration region under specified range gate and velocity gate of the radar seeker. The detailed instruction and analysis are given for each of these regions. Finally, the simulation proves the feasibility of the presented method. [ABSTRACT FROM AUTHOR]

With the development of wideband radar technology, the narrowband ambiguity function (NAF), which is based on the narrowband echo model, is not effective to analyze the signal process issue of moving target echo. To solve this problem, the wideband ambiguity function (WAF) of stepped frequency (SP) waveform is proposed based on wideband echo model. The property of wideband ambiguity function was studied, from which we could prove that NAF is just an approximate to WAF under low velocity condition. Making use of WAF match point characteristic, a target detection method based on the amplitude of match point was advanced. Simulation results verify the effectiveness of the method. [ABSTRACT FROM AUTHOR]

A parameter encoding method of digital channelized receiver based on multi-beam amplitude comparison direction finding was proposed. The parameter encoding flow of digital channelized receiver was introduced. The key problems in the encoding process were discussed in detail, including the measuring method of direction of arrival (DOA) and the amplitude synchronization between channels. The pulse description word (PDW) encoding of digital channelized receiver is the same as that of traditional receiver. Practice has proved that this method can satisfy with real-time processing requirement of radar signal processor in complex electromagnetism environment. It has been applied to recon receiver in ESM system successfully. [ABSTRACT FROM AUTHOR]

Velocity measurement and compensation is the key issue of wideband radar signal processing. The algorithm of range profile cross correlation (RPCC) can independently achieve velocity estimation in stepped-frequency (SP) signal, but with limited measuring accuracy. Through the analysis of the RPCC envelop and phase, two velocity estimation algorithms were put forward: waveform analysis of RPCC and peak phase of RPCC, and the theoretical performance was derived separately. Then, a novel approach was designed based on the combination of two algorithms above, which was defined as accurate velocity measurement of RPCC. The precision of the proposed approach is approximate to that of Doppler velocity estimation, which can not only satisfy the accuracy requirement of velocity compensation, but also make it possible to the micro-motion target measurement. Simulation result has verified the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

To realize perception of local lunar surface under the condition of relative stationary before soft landing during moon discovery, a novel 3-D imaging method is proposed. The method is based on range high-resolution in altitude dimensional and 2-D receiving digital beam forming to radar scene floor. The outstanding feature is this method can realize 3-D imaging without relative motion between radar and target. According to imaging principle, the transmitting waveforms, antenna shape and size has been researched and designed; the choosing of imaging height and stepping size for scene scan were also discussed; the whole imaging processing flow was given and has been simulated using computer. Simulation results indicate that it can obtain 3-D coordinates of strong scattering centers accurately and reconstruct 3-D image of scene successfully. [ABSTRACT FROM AUTHOR]

A rapid detecting method based on target validity was proposed to improve detecting performance of cut-in target using vehicular radar. The Kalman prediction was used as the judgment criterion of target's validity which could be represented by valid probability. In consequence, by extending the searching range to sidelines and setting up an inheritance mechanism of valid probability, the detection rate of the cut-in target was quickened. The experiment results show that the proposed rapid detecting method is robust and it can remove the disturbance caused by roadside objects or false signals. Moreover, the real-time performance of detecting cut-in target is improved obviously. [ABSTRACT FROM AUTHOR]

An improved method of calculating space-borne synthetic aperture radar (SAR) Doppler parameters is presented. The method relates to the satellite ephemeris. The improved method introduces J2 perturbation influence on perigee amplitude and longitude ascending node to Doppler parameters calculation effectively and obtains more accurate Doppler parameters. The difference between the traditional method and the improved method is analyzed, and the accuracy of the improved method is verified through computer simulation. [ABSTRACT FROM AUTHOR]

A new detection scheme for range-spread broadband radar target using high-resolution range profiles (HRRP) is proposed. The location of the target and the noise power were estimated in a window function, and a fuzzy threshold map was used to refine the target data, then enveloped alignment was carried out through the target moving with a constant velocity. Finally, the detector of fuzzy threshold map dependent generalized likelihood rate test (FTMD-GLRT) was derived based on the estimation of signal steering vector. Remarkably, the detection scheme ensures the constant false alarm rate (CFAR) property with respect to the unknown noise power. Experimental results of the measured data of three kinds of planes show that the proposed scheme achieves a visible performance improvement compared with the scatter density dependent generalized likelihood rate test (SDD-GLRT). [ABSTRACT FROM AUTHOR]

Based on the principle of range-Dopple(R-D) algorithm, for low-orbit satellite targets and given azimuth resolution, the accumulation time is analyzed. The result is verified using actual radar and target parameters. According to the algorithm and system parameters, the demanded computation and memory for real-time imaging processing is derived and a multi-channel real time ISAR imaging system is designed and implemented. The actual experiment has obtained good multi-channel imaging result and indicated that the design is effective. [ABSTRACT FROM AUTHOR]

A parallel radar signal processor framework based on StarFabric interconnection is proposed, and transfer performance of the StarFabric network analyzed by mathematical modeling. At the same time, digital signal processing(DSP) module and other module were designed. DSP module integrates 8 C64 x DSP and 2 GB memory. Other modules have the same connection interface but with different function circuit. The framework and the modules had been applied in a SAR jamming signal processor. [ABSTRACT FROM AUTHOR]

A new coherent detection method based on generalized likelihood ratio test(GLRT) and constrained GLRT(CGLRT) is proposed, which can be used in coherent detection for frequency diversity separated sub-array radar. The Keystone transform is employed to compensate the Doppler frequency discrepancy introduced by frequency diversity. Theoretical analysis and simulation results show that frequency diversity separated sub-array radar obtains better detection performance and better angle ambiguity resolution performance compared with its counterpart using single frequency, and the Doppler frequency discrepancy can be compensated by the Keystone transform regardless of the unknown target radial velocity. [ABSTRACT FROM AUTHOR]

In order to realize obstacle recognition of unmanned ground vehicle (UGV) in unpredicted environment, and to improve the accuracy of recognition, a system based on three-dimensional radar is proposed. A classification algorithm is given according to its function, angle and distance are used as two thresholds to classify data. Then the blocks which impede the vehicles can be detected. The reliability of the system and the veracity of the algorithm are verified through experimentation. The system can provide a real-time evaluation method in unpredicted environment for intelligent vehicle. [ABSTRACT FROM AUTHOR]

The memory attenuated Kalman filter (MAKF) algorithm is introduced for radar tracking and measurement of high dynamic target's range and velocity, and a new determination method of memory attenuated factor which can judge and repress the filter divergence is proposed. The algorithm increases the weight of measurement in state estimation, so the biases of range and velocity caused by acceleration can be eliminated, and the filter divergence caused by high dynamic target can be repressed. The simulation results showed that the performance of the proposed algorithm and the standard Kalman filter (KF) algorithm are similar in low dynamic situation, while the systematic biases and the random errors of the proposed algorithm are significantly smaller than the standard KF algorithm in high dynamic situations. The proposed algorithm can also repress the filter divergence caused by the general accelerated motion. [ABSTRACT FROM AUTHOR]

Based on the signal processing theory of stepped-frequency radar, the target motion compensation for the system is studied. According to the characteristic of possible multi-target in radar eyesight under real scenario, the method of compensation in frequency domain is presented. The method can be used in the compensation of multi-targets with relative motion so as to supply the traditional compensation method in time domain. The results of computer simulation verified the validity of this method. [ABSTRACT FROM AUTHOR]

According to the structure of sum-difference patterns phase-comparison two-dimension mono-pulse radar system, the system is divided into three parts, including the antenna-comparator, comparator, and channel processing circuitry. The impact of their non-ideal to the performance of angle measurement is analyzed and simulated. Some meaningful conclusions are acquired. The amplitude imbalance of antenna-comparator has influence on measured angle value but sign, and the phase imbalance has influence on both the measured angle value and sign. The impedance inconsistency of comparators affects both measured angle value and sign. The amplitude imbalance of channel processing circuitry affects the measured angle value and the phase imbalance affects measured angle sign. Furthermore, in the non-ideal factors, the impact of phase imbalance of antenna-comparator is the least, and the amplitude imbalance of antenna-comparator as well as the impedance inconsistency of comparators is great. [ABSTRACT FROM AUTHOR]

This article briefly analyzes the working process of photovoltaic radar of a certain plane and intraduces the software and hardware design of the equipment for detecting synthetic photovohaic radar parameters based on virtual instrument technology. This thesis emphasizes the common process of testability design and the application in the equipment. The automatic detecting capability of testing and isolating faults in the equipment is obtained due to the application of bulb-in testing (BIT). Thus, the maintainability, usability and reliability of the equipment are effectively improved. [ABSTRACT FROM AUTHOR]

A parameter design method is proposed for the signal acquisition of tracking and measurement radar with pseudo-random number (PN) code modulated continuous wave. The method uses FFT algorithm to implement time-domain correlation between received signals and local regenerated signals by frequency-domain spectrum multiplication, so that the acquisition time can be decreased significantly, then introduces non-coherent integration to increase the signal to noise ratio for weak signals. Tong multiple trial is applied to make the probability of false alarm meet system requirement. Parameters determination method is proposed to select the times of non-coherent integration and the parameters of Tong multiple trial. Results of simulation verified that the proposed method can meet the predetermined probability of detection and false alarm under low signal to noise ratio. [ABSTRACT FROM AUTHOR]

Aiming at the solution of sidelobe problems of phase-coded radar signals, a novel method of code agility is proposed here. Different codes selected randomly are transmitted from pulse to pulse, and the return waves are projected to the radar line of sight after matched filtering for eaeh echo and DFT processing for each range cell. A criterion for code selection is established as well. Theoretical analysis and experiments indicated that this technique suits for various biphase codes or polyphase codes, with perfect effect of sidelobe suppression. In addition, the capability of small targets detection is improved. Furthermore, good reduction performance can be retained even if target return waveforms are eclipsed to a great extent due to high duty cycle. [ABSTRACT FROM AUTHOR]

According to the problem of target range migration through resolution cells in a long-term integration, a long-term coherent integration method is proposed to maintain the detection sensitivity of the radar. It makes use of the cued velocity for a coarse velocity compensation, and then Keystone transform is adopted for the completion of the migration compensation. The coherent integration is finally carried out by Doppler processing. Computer simulation results showed the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Two key problems for inverse synthetie aperture radar(ISAR) imaging simulation of maneuvering targets are the high accurate simulation of raw signal and high resolution imaging processing. Instead of the traditional point-target model for raw signal simulation, full-wave numerical method is used to compute the scattering field of maneuvering targets under instantaneous position and attitude. Following a sequence of time delay, the raw signal is obtained by overlapping the scattering field on discrete time. According to resolution deterioration due to target maneuvering, ISAR imaging based on time-frequency transform is performed. Feasibility of this simulation approach is validated by simulation results presented. [ABSTRACT FROM AUTHOR]

A new approach of automatic classification of the radar emitter signals is presented. This method is based upon the characteristics derived from instantaneous frequencies and contains three sequential steps: firstly, the instantaneous frequencies of radar emitter signals are extracted via the improved instantaneous autocorrelation algorithm; secondly, a two-times-normalizations based feature re-extraction approach is used to obtain the classification characteristic vector; finally, the kernelized fuzzy c-means clustering with validity assessment is carried out to categorize the considered signals automatically. The results of simulation experiments show that, the characteristic vector can reflect the differences of signals with different modulation types and has a good ability to resist noises. The proposed scheme of signals classification can achieve the overall success rate of above 95% , even at the signal to noise ratio of 6dB. [ABSTRACT FROM AUTHOR]

To better apply the ADBF at subarray level to the phased array radar, the two-dimensional ADBF method at subarray level was studied. A signal model of ADBF at subarray level is presented, which is suitable for plane phased array. The normalization method was introduced into the two-dimensional ADBF at subarray level, which normalized the subarray outputs to make the noise power of each subarray be the same, and the desired quiescent pattern was achieved in the absence of jammer, thereby the conversion problem between adaptive and non-adaptive work modes was resolved. The method based on normalization processing can suppress jammer effectively and improve the sidelobe level markedly compared with the conventional method in the presence of jammer. Simulation results indicate the validity of the introduced methods. [ABSTRACT FROM AUTHOR]

According to the coherent phase-coded pulse train (CPCPT) signals used in terminal radar seeker, a long-term coherent integration method is proposed. Without requiring any accurate velocity information, Keystone transformation is used for range migration compensation. Fourier transform is carried out for the coherent integration. In order to reduce the computation complexity, DFT-IFFT algorithm is used for the implementation of Keystone transformation. In support of the method, CPCPT maintains the coherent integration gain and the resolution in range and Doppler without the range-Doppler coupling. Some computer simulation results are presented which illustrate the effectivity of the method. [ABSTRACT FROM AUTHOR]

Keystone transform has been employed to remove range migration in high resolution range bins of moving targets among different stepped-frequency frames, and a new signal processing method using multi-frame stepped-frequency signals is analyzed and evaluated, with which high resolution range-velocity image of moving targets can be achieved. Theoretical analysis and simulation results showed that as long as parameters are properly designed, the method can achieve coherent integration of all moving targets between multi-frame stepped-frequency signals regardless of their unknown velocity. Moreover, thanks to great increase in coherent integration time, the capability of detecting small targets can be improved. [ABSTRACT FROM AUTHOR]

To implement a portable meter wave radar, a three-channel interferometer AOA(angle of arrival) estimation method is proposed. The method implements the targets location in the whole space with only three receiving elements. Because the three receiving elements are placed on the vertexes of an equilateral triangle, the azimuth and elevation angles can be calculated through the phase differences between different elements. The phase differences are obtained by the method of FFT. For a moving target detection radar, the phase differences of the three elements can be calculated from the three channels' moving target detection(MTD) results. Then the angle of arrival(AOA) estimation based on three-channel interferometer can be achieved. It gaves the structure and implementation process of a typical radar location system based on the method. The reasons affecting the performance of the AOA estimation method are analyzed. Results of Monte-Carlo signal simulations with inputs in different SNRs are presented to demonstrate the angle accuracy performance, showing that the AOA estimation method is effective and practical. [ABSTRACT FROM AUTHOR]

In the wideband conical scan radar, the sensitivity to the radial velocity between the radar and the target induces the range migration through resolution cells among the high range resolution profiles. It results in the failure of the conical scan angular measurement algorithm. In this paper, Keystone transform is used for range migration compensation without requiring any accurate velocity information. By the transform, the range profiles are realigned and the angular measurements are obtained correctly by the conical scan algorithm, even if a high radial velocity exists. Some computer simulation results are presented which illustrate the effectieness of the method. [ABSTRACT FROM AUTHOR]

Based on parallel digital signal processing (DSP) technology, the design and implementation of a real-time quick look system is presented. Many kinds of quick look imaging algorithms of spaceborne synthetic aperture radar (SAR) are compared. According to certain parameters of spaceborne SAR system, an optimized real-time imaging algorithm is proposed. The system is used to fulfill 1/4 of range resolution and four-look of azimuth real-time imaging of L band spaceborne SAR Data. Finally, the results of image quality measures are given. [ABSTRACT FROM AUTHOR]

Under a symmetric multiprocessors (SMP) cluster environment, parallel computing of phased array radar simulation system is investigated to reduce simulation time. A coarse-grained message passing interface (MPI) distributed memory and fine-grained OpenMP shared memory hybrid parallel computing method is presented based on the relative independence of the phased array radar multibeam processing and the distance unit sampling computing in the signal processing simulation. Experimental results showed that the simulation speed is greatly enhanced by parallel computing. [ABSTRACT FROM AUTHOR]

Studies the measuring distance of wind profiling radar and the rules of change of structure coefficient for troposphere atmosphere turbulence(Cn²) for different seasons in China. According to the test records of wind profiler in recent years, analyzed and discussed experimentation data of north China and the principles of wind profiler compostion were introduced. Wind profiler radar equations and formulas of maximum measuring distance estimation were also derived. It is concluded that Cn² changes in different areas is the main reason for wind profiler measuring distance estimation errors. The test data proves the undulation of C̄n². with seasons is not very obvious and smaller than that of the boundary-layer atmosphere. Furthermore, the loss of signal processing is not the ignored factor for wind profiler measuring distance estimation. [ABSTRACT FROM AUTHOR]

Intermittent clutter produced by flyers such as birds is a severe interference for wind detecting. For resolving the problem of clutter rejection, a method based on wavelet coefficients replacement is suggested. According to the clutter characteristics of the clutter bursting and short duration gained by the echoes analyzing, a novel method for the clutter recognition based on power consistency checking of different spectral integration signals in the wavelet transform domain, clutter discriminant function and clutter suppression method based on counterpart scale wavelet coefficients replacement are proposed. By the data measured from field testing, high efficiency of clutter rejection is verified. [ABSTRACT FROM AUTHOR]

A novel double vertical half-wavelength dipole antenna is studied. Its main structure and advantages of this novel antenna is presented. 3D electromagnetic numerical method is utilized to analyse and simulate the antenna performance. Measurement results proved that the realized antenna has good electrical performance in operating bandwidth, voltage standing wave ratio(VSWR) and antenna pattern. It also has a high ratio of performance to cost. Finally, application of the antenna in portable tree surveillance radar and large scale air surveillance radar is discussed. [ABSTRACT FROM AUTHOR]

A new digital radio frequency memory (DRFM) system architecture based on digital channelized receiver is introduced. The theory of channelized receiver is stated and the realization structure based on polyphase filters is derived, and the diagram of radar countermeasure system based on this idea is proposed. The DRFM system based on digital channelized receiver take the advantage of broadband coverage of channelized receiver, and guarantees the frequency accuracy of the reproductive signals. The system can significantly reduce the requirement for calculation resources, the complex modulation process can easliy be achieved due to the decimated low speed data rate. [ABSTRACT FROM AUTHOR]

To improve the data rate of step frequency radar system, a velocity compensation method is proposed. It uses the effects of the quadratic phase created by moving target to obtain the real velocity without PRF stagger. Requirements of new algorithm for different parameters are studied. Theory and simulation results showed the efficiency of the proposed method. It provides a foundation for the theory of step frequency radar system. [ABSTRACT FROM AUTHOR]

Investigates a signal processor of electromic warefare(EW) digital receiver based on FFT/IFFT algorithm, and realized completely by FPGA constructed annularly. Four FPGAs implement respectively the high-speed data transmission interface, FFT/IFFT operation and signal detection in the time/frequency domain. The FPGAs run with distributed, multi-bus, parallel and pipeline mode. This processor can detect the parameters of carrier frequency and pulse description word for 4 simultaneous-arrival signals at most, and they need only about 20 ms to detect 4 signals while 256 K(1 K= 1 024) point FFT and 32 K point IFFT are adopted. The data receiving, operating and signal detection in time/frequency domain are realized on a board. [ABSTRACT FROM AUTHOR]

In order to provide a good simulation platform to study the passive radar seeker, video signal simulation was adoped to model and simulate the passive radar seeker, and a simulation platform was built up. In the experiments, the simulation results of passive radar seeker in typical war environment were provided, which verifies the correctness of our model and the robustness of our platform. [ABSTRACT FROM AUTHOR]

In order to implement the real-time capability of spaceborne SAR quick-look system, according to the characteristics of spaceborne SAR quick-look imaging algorithm, the impact from range migration that affects the azimuth matching is analyzed. As to the most time-consuming part in a quick look algorithm, the improved azimuth match algorithm is discussed in detail and realized. The optimized result indicates that the operation-amount descends by a tenth, and that realtime processing of quick-look system is realized. [ABSTRACT FROM AUTHOR]