Time filter

Source Type

Lu T.-Y.,Beijing Institute of Technology | Yin J.,Beijing Institute of Technology | Yin J.,Academy of Equipment Command and Technology | Xia Q.-L.,Beijing Institute of Technology | And 2 more authors.
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2015

Aiming at the problem of fluctuation of line-of-sight rate estimate caused by phased array seeker discrete beam motion, a line-of-sight rate extraction algorithm is presented, which uses beam angle error compensation. The strapdown phased array seeker discrete beam motion principium is analyzed, and the mathematical model of beam scanning control is proposed. The disturbance rejection transfer function caused by beam angle direction error slope is derived. The method of using beam angle direction error compensation is analyzed and described. The simulation results show that by using beam angle direction error compensation method, the fluctuation of line-of-sight rate estimate can be effectively eliminated, and the algorithmic validity of decoupling and line-of-sight rate extraction is proved.

Wu X.,Beihang University | Wu S.,Beihang University | Xing Z.,Beihang University | Zhang W.,Beijing Huahang Radio Measurement Institute
Proceedings of the 2015 27th Chinese Control and Decision Conference, CCDC 2015 | Year: 2015

The problem of seeker allocation and target assignment (SATA) of multiple hetero-seeker missile formation in the anti-ship cooperative attack was investigated in this paper. A calculation model of penetration probability and a model of SATA for the missile formation attack were designed, considering the characteristics of the missile seeker, the operational process of the missile formation cooperative attack, the shipboard anti-missile weapons with the constraints of the ammunition restrictions and the target value. Then a method based on genetic algorithms (GA) was presented, with novel encoding, modified initialization, crossover and mutation operations. Simulations demonstrate the viability of the proposed method, showing that the missile formation penetration probability increases by 10% using the proposed algorithm; it could provide basis and reference for actual combat operation. © 2015 IEEE.

Lan S.-C.,Harbin Institute of Technology | Zhang X.,Beijing Huahang Radio Measurement Institute | Pan R.,Harbin Institute of Technology | Li J.-H.,Harbin Institute of Technology
Proceedings of the 2011 6th IEEE Conference on Industrial Electronics and Applications, ICIEA 2011 | Year: 2011

Considering the on-board clock stability, the paper presents a method of timing calibration strategy based on the observation of pulsars, a natural celestial source, in order to improve the timing accuracy. A calibration model is established and the error factors are considered based on the characteristic of pulsars' stable and periodical signals, and the pulsar timing residuals are caused by reference normal clock and pulsar itself, and the two influences are not correlative. Firstly, filters such as wavelet and HHT are implementing to data handling and error analysis, and then the paper investigated and developed a multiple-pulsar-observation method. Judging from the signals transmitted from different pulsars, the onboard timing residuals are determined by credibility weight of different pulsars' observation different components. Finally this paper comes to the conclusion via simulations. The method allows separating the error from a single pulsar timing errors and the on-board time can be obtained by filtering the observation residuals of pulsars observed, extracting the filtering result of different pulsars, and then choosing the weight according to the stability of timing result denoted with timing variance. © 2011 IEEE.

Chen C.,Harbin Institute of Technology | Zheng Y.,Beijing Huahang Radio Measurement Institute | Hu S.-Y.,Beijing Huahang Radio Measurement Institute | Qiang W.-Y.,Harbin Institute of Technology
Yuhang Xuebao/Journal of Astronautics | Year: 2011

Frequency agility and coherent process technique used in radar are combined. In this context, the phase changes of the moving target echo are analyzed. Factors affecting the coherent include two coupling terms, carrier frequency versus range and carrier frequency versus velocity. Effective coherent methods on phase compensation are proposed, which include the irregular pulse repetition interval method and the cost-function based compensation method. The feasibility and versatility of this method are verified.

Jia X.,Harbin Institute of Technology | Zhao C.,Beijing Huahang Radio Measurement Institute
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2011

In modern tactical missiles terminal guidance system, strap-down stable scheme is prior to traditional gyro stable scheme in cost and volume, and is a new direction of missile seekers. The critical technique of strap-down terminal guidance system is the so called mathematical stabilization platform and strap-down stable control algorithm. The stabilization control scheme and guidance information extract approach of terminal guidance system with a semi-strap-down structure were discussed. A practical mathematical stabilization control algorithm and the relevant line of sight (LOS) angle rate extract method were devised, which was suitable for engineering implementation. First of all, the principle of strap-down stabilization control was discussed. After that, a new control law of the mathematical platform was described, together with a calculation algorithm of guidance information such as LOS angle and LOS angle rate. Moreover, in order to overcome the deficiency of calculation precision caused by imprecision of sensor's measurement and non-ideality of differential operation, a practical evaluation filter model of LOS angle rate was given out based on the angle tracking model of a missile to a target. Finally, computer simulations were made which verified the efficiency of above methods.

Chen C.,Harbin Institute of Technology | Qiang W.,Harbin Institute of Technology | Shan X.,Harbin Institute of Technology | Hu S.,Beijing Huahang Radio Measurement Institute
Proceedings of the 2012 International Conference on Computer Application and System Modeling, ICCASM 2012 | Year: 2012

This article presents a study for reducing the complexity of data association in multi-target tracking by using the target location data and associated Doppler information measured by radar. A scenario of using characteristic parameters to modify the nearest neighbor algorithm is illustrated in the study of tracking algorithm, and the simulation results verified the applicability and effectiveness of this method for engineering application. © the authors.

Huang P.,Xidian University | Liao G.,Xidian University | Yang Z.,Xidian University | Xia X.-G.,Xidian University | And 3 more authors.
IEEE Transactions on Signal Processing | Year: 2016

In the airborne or spaceborne radar applications, prolonging the coherent integration time is one of the effective methods to improve the radar detection ability of a weak maneuvering target, whereas the coherent integration performance may degrade due to the complex range migration (RM) and Doppler frequency migration (DFM) effects. In this paper, detection and motion parameter estimation for a weak maneuvering target with the third-order RM and DFM are considered. Firstly, Keystone transform is applied to compensate the linear range walk. Then, the matched filtering processing is performed in the range-frequency and azimuth-time domain to eliminate the residual coupling effects between range and azimuth. Finally, a well-focused image of a moving target is obtained, and three motion parameters, i.e., velocity, acceleration, and acceleration rate, are effectively estimated. In addition, as for a fast-moving target with Doppler ambiguity, two cases, i.e., target azimuth spectrum within a pulse repetition frequency (PRF) and spanning over neighboring PRF bands, are analyzed. Compared with the generalized Radon Fourier transform (GRFT), the proposed method can acquire a close integration performance but with lower computational complexity since the parameter searching dimension is reduced. Simulated processing results are provided to validate the effectiveness of the proposed method. © 1991-2012 IEEE.

Shen H.,Ocean University of China | Wu S.,Ocean University of China | Qin S.,Beijing Huahang Radio Measurement Institute | Liu J.,Ocean University of China | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

Frequency stability of Q-switched Nd:YAG laser significantly affects the wind measurement accuracy of direct detection Doppler Lidar. The typical free frequency drift of diode-pumped Nd:YAG laser working at doubling frequency 532 nm based on seed injection can reach 15 MHz/min, correspondingly to a weed speed measurement error of 4 m/s. By using virtual instrument control technology of Labview, the frequency of pulsed laser is successfully scanned, and iodine absorption line 1109 is matched automatically, which get the frequency on one of the two slopes of the line. Standard deviation of frequency stability is about 0.8 MHz for a long time (more than 2 h), while the equivalent wind speed error is 0.2 m/s. The requirement of frequency stability is achieved during long-term lidar measurements.

Wang W.,Harbin Engineering University | Liang D.,Harbin Engineering University | Wang Z.,Beijing Huahang Radio Measurement Institute | Yu H.,Harbin Engineering University | Liu Q.,Harbin Engineering University
Radioengineering | Year: 2015

The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coupling effect within the array. The signal processing platform is based on an efficient field programmable gates array (FPGA) and digital signal processor (DSP) pipeline where a robust beamforming imaging algorithm is running on. The radar system was evaluated through a real field experiment. Imaging capability and real-time performance shown in the results demonstrate the practical feasibility of the implementation.

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