Time filter

Source Type

Shen J.,Nanjing Changjiang Electronics Group Co. | Li H.,Nanjing Changjiang Electronics Group Co. | Wu C.,Nanjing Changjiang Electronics Group Co.
2010 9th International Symposium on Antennas Propagation and EM Theory, ISAPE 2010 | Year: 2010

The design of a IFF (Identification Friend or Foe) interrogator antenna (hereafter referred to IFF antenna) sharing the shaped reflector with the C-band radar is described. To ensure that each feed operates properly in the presence of the other, dipoles elements were tried as IFF feed, IFF feed elements beside and under the radar feed horn were also tried. In the end, two dipoles were used as IFF feed and were located under the radar feed horn, yielding approximately a 9° azimuth beamwidth and 1.7 dB per degree horizon cutoff. The sidelobe level of the sum beam is about -40dB, the difference beam is below -25dB. ©2010 IEEE.


Wang X.-D.,Nanjing University of Aeronautics and Astronautics | Wang X.-D.,Nanjing Changjiang Electronics Group Co. | Fan T.,Nanjing University of Aeronautics and Astronautics | Huang Q.-H.,Nanjing Changjiang Electronics Group Co. | Zheng B.-S.,Nanjing University of Aeronautics and Astronautics
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2016

SOQPSK signal has constant envelope and continuous phase, and has high power and spectral efficiency. It will have broad application prospects in satellite communications, deep space communications and aeronautical telemetry systems. To ensure SOQPSK carrier signal can be applied to larger Doppler offset system, this paper presents a SOQPSK signal carrier tracking technology which uses FFT guide COSTAS loop. First, a rough estimate by FFT of the Doppler frequency makes carrier frequency offset be limited to a small range, and then uses the improved COSTAS loop to track carrier residuals and phase error, thus achieving a steady carrier track for SOQPSK signal with large carrier frequency offset. Simulation results show that the proposed algorithm not only is able to track large carrier frequency offset, but also is better to track small frequency offsets than traditional methods. © 2016, Chinese Institute of Electronics. All right reserved.


Sun W.,Nanjing University of Information Science and Technology | Sun W.,Nanjing Southeast University | Zhang X.,Nanjing University of Information Science and Technology | Sun Y.,Nanjing Changjiang Electronics Group Co. | And 2 more authors.
High Technology Letters | Year: 2012

According to the chroma distribution diversity (CDD) between lip color and skin color, the lip color area is segmented by the back propagation neural network (BPNN) with three typical color features. Isolated noisy points of the lip color area in binary image are eliminated by a proposed region connecting algorithm. An improved integral projection algorithm is presented to locate the lip boundary. Whether a driver is fatigued is recognized by the ratio of the frame number of the images with mouth opening continuously to the total image frame number in every 20 s. The experiments show that the proposed algorithm provides higher correct rate and reliability for fatigue driving detection, and is superior to the single color feature-based method in the lip color segmention. Besides, it improves obviously the accuracy and speed of the lip boundary location compared with the traditional integral projection algorithm. Copyright © by HIGH TECHNOLOGY LETTERS PRESS.


Shi W.,Nanjing University of Aeronautics and Astronautics | Hu W.,Nanjing University of Aeronautics and Astronautics | Wang Y.,Nanjing University of Aeronautics and Astronautics | Wang S.,Nanjing Changjiang Electronics Group Co. | Liu X.,Nanjing Changjiang Electronics Group Co.
Shuju Caiji Yu Chuli/Journal of Data Acquisition and Processing | Year: 2013

When passive radar based on TV signals radiates electromagnetic wave outward to detect target, the high correlation of the horizontal synchronizing signals of TV signals causes target range ambiguity after testing. Meanwhile, the strong cyclical of TV signals itself confronts a problem that the influence of pulse pressure is not ideal. Therefore, to suppress range side-lobe better, a fast optimization algorithm is proposed, combining a mismatch filter with compressed sensing. The simulation result show that this optimization algorithm can solve the problem of range ambiguity.


Hu W.,Nanjing University of Aeronautics and Astronautics | Hu W.,Nanjing Changjiang Electronics Group Co. | Zhao G.-H.,Nanjing University of Aeronautics and Astronautics | Zhang G.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2012

A time scale is a nonempty closed subset of the real numbers R. Recently, the dynamic equations on time scale have received much attention, which have the generalized forms of differential and differential dynamic equations. In this paper, we study the stabilities of fixed points and bifurcations of the sine dynamic equations on time scale. The results show that the solutions of the sine dynamic equations become different with the time scale parameter changing. And n-period-doubling bifurcations and splits of fixed points are observed. Moreover, the chaotic parameter spaces of the dynamic equations are expanded by the increase of complexity of time scale but without increasing the system parameter, thus providing a potential advantage for chaos encryption, radar waveform design and other application areas. ©2012 Chinese Physical Society.


Hu W.,Nanjing University of Aeronautics and Astronautics | Hu W.,Nanjing Changjiang Electronics Group CO. | Li J.-P.,Nanjing University of Aeronautics and Astronautics | Zhang G.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2012

We proposed a new chaotic system using the closed loop self-feedback frequency modulation (FM) technique where the current sample of the output signal of voltage-controlled oscillator (VCO) is transformed and used as the next input of VCO. The dynamical behavior of the system is investigated by Bifurcation diagram and Lyapunov exponents. The performance of the system is analyzed in terms of peak to average power ratio (PAPR), frequency spectrum and the correlation function of the output signal. The results show that the developed system has complicated dynamical behaviors, including bifurcation, multi-stability and chaos, and the generated chaotic signals have low PAPR and wide bandwidth. We also discussed the synchronization of the system by FM code. In circuit experiments, VCO is implemented by digital frequency synthesis. The experimental results are consistent with our theoretical analysis. © 2012 Chinese Physical Society.


Hu W.,Nanjing University of Aeronautics and Astronautics | Hu W.,Nanjing Changjiang Electronics Group Co. | Bao B.,Jiangsu Teachers University of Technology | Zhang G.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | Year: 2010

The blind identification of linear convolution systems driven by a piecewise linear continuous chaotic signal was researched, and a chaos synchronization based identification approach for linear convolution systems is proposed. By utilizing linear matrix inequality (LMI) and chaos synchronization systems, a least square based observer was constructed and minimized by an adaptive algorithm to estimate the parameter of linear convolution systems. A simple piecewise linear chaotic system was used in simulation analysis. The numerical simulation results are consistent with theoretical analysis results, which demonstrate that the proposed approach can identify the convolution systems. And the proposed approach converges only after about ten iterations. The proposed approach is more robust than the traditional Bussgang algorithm. When input SNR is 15 dB, the output SNR (signal to noise ratio) of the proposed approach is 10 dB higher than that of the Bussgang algorithm. And even when imput SNR in 0 dB the proposed approach has output SNR of 5 dB.


Jianguo M.,Nanjing University of Aeronautics and Astronautics | huiyu Z.,Nanjing University of Aeronautics and Astronautics | Guangmin L.,Nanjing University of Aeronautics and Astronautics | Jiankang X.,Nanjing Changjiang Electronics Group Co.
Applied Mechanics and Materials | Year: 2013

This template explains a design of a fuzzy temperature control system for the pressuresensitive paint. According to the relationship between temperature difference and the current of semiconductor chip, the fuzzy system control theory, control the volume of the domain, control rules design, and design a constant current source circuit to control the current through the chip, and finally make experimental verification of the system. The system hardware uses C8051F040 MCU, temperature chip DS18B20, keyboard chip CH451. © (2013) Trans Tech Publications, Switzerland.

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