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25 April 1986, Volume 6 Issue 02 Previous Issue    Next Issue

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THE PERFORMACE ANALYSIS FOR DETECTION MODEL OF FRAME SYNCHRONOUS IN DIGIT COMMUNICATION (一) Chen Yiyuan Han Guangxi 1986, 6 (02):  1-9+18.  Abstract ( 2836 )   Save This paper puts emphasis on discussing the performance analysis for detection model of frame synchronous codes under the stable comdition of bits synchronization. In the space digit communication, we often adopt the detection model with both fixed correlation and maximum correlation level criterions. Here, we calculate the detection probability, set up the state model of detection process and deduces the equation of estimating, synchronous detection time. Hence, it provides scientific basis to performance analysis, for the two detection devices and profits selecting the parameter for the frame synchronous detection devices. Related Articles | Metrics

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THE TWO-WAY DOPPLER RANGE-RATE MEASUREMENT Chen Qin-nan 1986, 6 (02):  10-18.  Abstract ( 1733 )   Save The two-way Doppler equation isderivated according to the concept of the two-way Doppler range-rate measurement. The major measure methods and error sources are suggested and the analysis of the average error of the Doppler measure method is put forward. For direct sensing, the Doppler factor is derivated using the geometry method. A more ideal measure method based on discussing two conventional measure methods is suggested.The method has been applied to a practical equiqment. In order to analyse the range-rate error, ten major error sources is taken into acc0unt. Among other things,the tenth error source must be considered in the case of the rotation satellite using paetical antennas. Finally, the emphasis is laied on the average error of the Doppler measure method. On the basis of getting a clear understanding of the average error concept, the major factors to influene the error are analysed. Related Articles | Metrics

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A CONDITION APPROXIMATE TO CICRE FOR GROUND TRACKS OF EARTH SATELLITE Fan Jianfeng 1986, 6 (02):  19-28.  Abstract ( 1656 )   Save This paper presents a condition approximate to cicre for ground tracks of satellites moving in any elliptic orbits, and some aplications in the preliminary design of satellite orbits. Related Articles | Metrics

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MULTI-STATE FAULT-TREE ANALYSIS Liao Jiongsheng 1986, 6 (02):  29-37.  Abstract ( 1727 )   Save Usually, only two states (failuse/success) of the bottom and top event are considered in FTA. But in the real world, the system and its components are capable of being in different failure modes and in a whole range of failure. Therefore, it necessary to develop the multi-state FTA approach. In this article, the multiple-valued logic is discussed, the disjaint Boolean algebraic method to analyze the fault tree with multi-state components is presented, and an example of FTA is introduced, in the later the statistically depedent events is replaced by a multi-state component. Related Articles | Metrics

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SYNCHRONIZATION AND BUFFER FOR IMAGE DATA Sun Huaisu 1986, 6 (02):  38-48.  Abstract ( 1951 )   Save In geostationary meteorological satellite systems raw data obtained from visible infrared spin-scan radiometer (VISSR) has to be synchronized and buffered before it is sent to data processing center(OPC). Synchnonzation is necessary for recovering a good image in which the pixeles are precisely positioned and for the accurate measurement of wind speed which is a majorapplication of the data, and buffering is for easing data transmission and interconnectionwith computers.So, from the point of view of utilizing the data correctly, syn chronization and buffer are indispensable techniques in the systems. This paper presents the fundamental functions and the detailed features of the synchronizer/data buffer (S/DB) systems which have been successfully used in Meteosat and GMS systems. Related Articles | Metrics

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POWER SPECTRUM ANALYSIS AND EXPERIMENTAL RESEARCH OF PN CODE MODULATED QPSK WAVES Lin Ke-xiang Wang Ming-yuan 1986, 6 (02):  49-57.  Abstract ( 1693 )   Save The theoretical analysis and experimental research of The principles of QPSK with ECL XOR gates and the power spectra of PN code modulated QPSK waves are done. The experimental results are well conformed with the theoretical analysis. Related Articles | Metrics

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MICROWAVE INTEGRATED DOWNCONVERTER USED IN UNIFY CARRIER FOR C BAND Liu Le He Yu Xiu Ming Cai Shui Yin Huang Rong Lia 1986, 6 (02):  58-62.  Abstract ( 1849 )   Save The microwave integrated downconverter used in unify Carrier for c band is specially designed for satellite communication earth station. It has three channels. Features of each channel are as follows the net gain about 20dB, the NF less than 8dB, the interfering signal output level is less the 12MV for the prime-amplifier, the root-mean-squaz of flat-phase difference between each two channel is less than 0.3 degree, the insulation among three channels is more than 60dB, and the increment of gain amony three channels is less than ±0.5dB. The downconverter can track and telemeter up to twenty-seven frequency signals by means of chosing a correct local cscillating frequency. Related Articles | Metrics

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CHARGING AND DISCHARGING OF DIELECTRIC FILMS IRRADIATED BY COMBINED HIGH-/MEDIUM-/LOW-ENERGY ELECTRONS Yang Zhaoming, Zhou Yanping and Ge Reihong 1986, 6 (02):  63-69.  Abstract ( 1913 )   Save Exposure of Mylar and Teflon films to combine dhigh-/medium-/low-energy electrons has been performed whose results differ from that of exposure to medium-energy electron environment alone, combined high-/medium-energy electron environment, and combined medium-/low-energy electron environment. The experimental results have shown that dielectric discharge can be initiated by highenergy electron exposure. The results of exposure of Teflon films to combined high-/medium-/low-energy electron environment agree with that of exposure to 1—100keV dN/dE∝E~(-2) spectral energy electron environment and that of NASCAP computer simulation. It is concluded that combined high-/mediumow-energy electron exposure can perfectly simulate charging and subsequent discharging effects of dielectrics aboard geosynchronous satellites. Necessity and sufficiency of using electrons with the three different energies have been demonstrated. It is inferred that the surface potential of dielectrics on spacecraft surface will be raised and discharges will be initiated if high-and/or mediumenergy electron fluxes increase to an adequate value in geosynchronous orbit during geomagnetic storm or substorm. Related Articles | Metrics