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25 June 2003, Volume 23 Issue 03 Previous Issue    Next Issue

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Automatic Modulation Recognition of TTC Signals of Satellite Zhong Xingwang Chen Hao(Xi′an Institute of Space Radio Technology, Xi′an 710000 )Yi Kechu(Xidian University, Xi′an 710000) 2003, 23 (03):  .  Abstract ( 1648 )   Save This paper is about automatic modulation recognition of TTC(Tracking,Telemetry and Control)signals of satellites. The modulation schemes considered are FM and PM. Two algorithms are developed. The influence of carrier frequency offset on the probability of correct decision is considered and some carrier frequency excursion estimation algorithms are used to remove the influence. According to the computer simulation experiment, it is found that the least-squares algorithm is an effective method to remove the influence of carry frequency offset and part noise in the algorithm based on standard deviation of the direct value non-line component of instantaneous phase( σ dp ), and that the probability of correct decision is up to 100% in the algorithm based on standard deviation of the direct value of instantaneous warped phase( σ dwp ),when the signal-to-noise ratio is higher than negative 6dB at the presence of 100Hz carry frequency offset. Related Articles | Metrics

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Analyses of the Absolute Motion and Relative Motion for Space Rendezvous V-bar Approach Using Impulsive Maneuver Zhu Renzhang Lin Yan(Beijing University of Aeronautics and Astronautics, Beijing 100083)Li Yili(Chinese Academy of Space Technology, Beijing 100083) 2003, 23 (03):  .  Abstract ( 1662 )   Save The absolute motion and relative motion for space rendezvous V bar approach using impulsive maneuver are investigated in this paper, in terms of orbital perturbation equations and C W solutions. The results based on the analyses are useful for space rendezvous mission design. Related Articles | Metrics

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Simulation of Parachute Initial Inflation Phase PengYong Zhang Qingbin Cheng Wenke Qin Zizeng(College of Aerospace and Material Technology, NUDT, Changsha 410073) 2003, 23 (03):  .  Abstract ( 1714 )   Save An initial inflation model for parachutes is established. The forebody, suspension lines and canopy are modeled as a series of elastically connected mass nodes. The flow field inside canopy is one-dimensional incompressible flow. Finally, the model is used to calculate the variations of canopy shape, the variations of canopy projection area and the tension of suspension lines during initial inflation phase. Related Articles | Metrics

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Tracking and Navigating Filter for Maneuvering Target Li Hengnian Zhu Zhuanmin(Xi'an Jiao Tong University, Xi'an 710047) Li Jisheng(Xi'an Satellite Control Center, Xi'an 710043) 2003, 23 (03):  .  Abstract ( 1628 )   Save In view of the uncertainty of thrust acceleration, enormous error occurs in tracking and navigating maneuvering target during orbit transfer process. In this paper, three components of position and velocity with respect to ECI coordinate system are augmented with thrust acceleration to be augmented system states, whose dynamical equations and measure equations are developed in ECI frame, and a minimum variance filter for estimation of augmented system states is presented, and the issues on linearizing non linear augmented state equations are discussed in detail. Simulation results are employed to illustrate that the algorithm developed here can track and position maneuvering target in real time during orbit transfer process. Related Articles | Metrics

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The Parameter Optimization of Tripropellant′s Engine for SSTO Tan Songlin(The North West Polytechnology University, Xi′an 710072)Wang Hongrang(Airspace Propulsion Technology Institute, Xi′an 710100) 2003, 23 (03):  .  Abstract ( 1613 )   Save The parameter of tripropellants engine for SSTO is optimized on the basis of performance calculation with respect to dry mass of launcher. The optimized parameters and transfer time of engine are obtained corresponding to the dry mass of the least launcher, which will lay the foundation of the detailed design of engine in the future. Related Articles | Metrics

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Sensitive Analysis of the Dynamic Balancing of Small Satellites Hou Yuemin Ji Linhong Jin Dewen(Tsinghua University, Beijing 100084) 2003, 23 (03):  .  Abstract ( 1696 )   Save The effects of the mass eccentricity ( R c ), the allowed mass eccentricity( R c0 ),the balancing mass limit ( w b ), and the satellite mass ( M c ) on the total balancing mass ( W ) are analyzed based on the linear programming and the tool of balancing platform developed. It can be concluded that for certain balancing positions: 1) R c0 ∝1/ M c; 2) R c0 ∝ w b; 3) the increase of R c increases significantly W in the case of lower w b; 4) the increase of w b reduces significantly W in the case of larger R c. The conclusions are applicable for other aircrafts and mechanical products . Related Articles | Metrics

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Research on Configuration Analysis and Comparison of SGCMG System Zhang Jinjiang(Beijing Institute of Control Engineering, Beijing 100080) 2003, 23 (03):  .  Abstract ( 1688 )   Save The single gimbal control moment gyro (SGCMG) configuration of a large spacecraft is studied. First, the research object of analyzing configuration is restricted. Second, The double parallel configuration, three parallel configuration, the pyramid configuration, four ridge cone configuration ,five surface cone configuration and five ridge cone configuration are analyzed according to the main indexes of configuration analysis. The merits and shortcoming of each configuration are compared. The conclusion that the optimum configuration is five ridge cone configuration is deduced. This conclusion provides the academic foundation of selecting configuration in large spacecraft SGCMG system. Related Articles | Metrics

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Realizing A Ka-Band Fourth-Harmonic Mixer Ma Kaixue Zhang Haobin Chen Jianrong(Xi'an Institute of Space Radio Technology,Xi'an 710000) 2003, 23 (03):  .  Abstract ( 1991 )   Save The paper deduces the formulas for designing and realizing fourth harmonic mixer and presents the mixer formula through combine the theory of anti diodes and the theory of composing differential phase signals. Based on the formula, the scheme of realizing Ka band high IF forth harmonic mixer is given and then the circuitsimulation is performed and the mixer circuit is worked out. The results of simulation and test show that the formulas are correct and the scheme is practicable. Related Articles | Metrics

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Research on Second-Order Nonlinear Filter Technology for Processing Satellite Attitude Measurement Information Lin Yurong Deng Zhenglong(Harbin Institute of Technology, Harbin 150001) 2003, 23 (03):  .  Abstract ( 1553 )   Save The stringent attitude orientation accuracy demanded by the satellite flight omission motivate the development of recursive nonlinear filters for precise attitude estimation. This paperpresents the second order attitude estimator for the typical stellar inertial attitude determination system using the nonlinear filter based on the second order Taylor series approximation. In addition , the QUEST algorithm is efficiently combined with the attitude estimator as the compressing technique of multi vector observation information in order to simplify the update implementation . Performance comparison by computer simulation under the same conditions demonstrates that the second order nonlinear attitude estimator consistently performs better than the first order linear attitude estimator using the extended Kalman filter technology. Related Articles | Metrics

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Design Twin-Station LEO Satellite δ Constellations for Regional Coverage Zhang Juan He Xingsuo Zhang Liexia Deng Fengyan(Northwestern Polytechnical University, Xi′an 710072) 2003, 23 (03):  .  Abstract ( 1497 )   Save The Twin Station LEO satellite constellations for regional coverage are suggested in this paper using point coverage simulation method. The constellations have 41° inclination retrograde orbit. The advantage of Twin Station system can be showed in these constellations. The constellations can offer single and double regional continuous coverage to China and the space station . The Inter satellite Links are established among the satellites of the constellation and the satellite links between constellations and space station are also established, which can ensure the data passing continuously among space station, ground station and constellations. Related Articles | Metrics

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The Study of Precise Orientation Based on Two GPS Receivers You Hongjian Su Lin(Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101) 2003, 23 (03):  .  Abstract ( 1711 )   Save Two or more GPS receivers can be used to determine the orientation or attitude of objects except that GPS can be used to determine the position, velocity and time. How to determine the orientation precisely based on carrier phase synchronization provided by two GPS OEM boards is studied in depth in this paper. The double difference of carrier phase is formulated first and then the orientation and pitch are searched in two dimensional space based on the baseline between the two GPS receivers. The ambiguity function is used as the judgment criterion to search the azimuth and pitch. At last, the baseline vector of the two GPS receivers is determined using the least square and the accurate azimuth and pitch are calculated based on the accurate baseline vector. Many test results show that the method is feasible and the accuracy can reach 0 08 degree with a 5 meters baseline and it only takes 1 3 minutes to determine orientation in real time. Related Articles | Metrics