Application Research On Orbit Managing For Geosynchronous Communication Satellite

The management of geosynchronous communication satellite is fulfilled through orbit measuring, orbit determination and orbit keeping (maneuver). Orbit measuring is also called the ranging. The prevail measuring and controlling system in China is the unified carrier TTC system, mainly used for ranging through multiple side tone. One of the difficult points for measuring system is that the utmost unambiguous distance is limited by the lowest frequency of tone. Other on orbit satellite accurate station keeping. During the period of my master degree studying, I was engaged in the GEO satellite operation always in China Orient Satellite Telecommunication Co. LTD. I took part in some telecommunication satellite on orbit operation and station keeping. Regards to the GEO communication satellite orbit management, I performed some quit deeply researching.The thesis offers the concrete solutions for the utmost unambiguous distance of effectively increasing the side tone ranging system. Given the ranging data, satellite's orbit is calculated based on the distance, angle, radial speed and time stamp, etc. Besides, from the side of the engineering application, the article presents in detail the reason why the geosynchronous satellite excurses in the designated position and the calculation method, as well as the large amount of the practical ranging data and implementary strategy for orbit regular keeping by dividing the E/W orbit correct area (window) through the current China Satellite No. X. Article origination:Article 2:Look on the "ChinaSat X" as the example, performed:ranging scenario analysis, described ranging system operation processing, analysis with ranging error and elimination method, the detail of side tone ranging technology. Article 3:Look on the "ChinaSat X" as the example, researched the side tone ranging production, due to the two double technology, complementary tone technology improved ranging accuracy in the side tone ranging system and maximum non-inkling distance. Article 4:Look on the "ChinaSat X" as the example, introduced caused reason and calculation mean of GEO communication satellite orbit drift in detailed. Article 5:the E/W station keeping mean of GEO communication satellite was investigated regards to as the following:the satellite mean longitude drift, tracking station accuracy, force error of on board thruster, the coupling with south/north maneuver to east or west maneuver on board, etc. Per as to above, it introduced a mean which is how to specific the orbit control windows and to estimate eccentricity control radius field. The following problems have been solved:1, In order to generate the low frequency of range tone, the DDS has been applied in the multiple side tone system to produce the sine wave at any frequency. As for the PLL (Phase-Locked Loops) interference caused by the low frequency, it works out through moving the low frequency out of the signal band of PLL by two-double tone technology. The question about the bandwidth of multiple side tone is broad and inefficient utility, it is made up by complex tone. Finally by multiplexes circuit it achieved to increase the accuracy of measurements, enlarge the maximum unambiguous distance, and avoid investing on more equipment.2, Due to the fact that the zone 1 used for mean longitude control is asymmetry between east and west part, the zone 2 allocated for eccentricity control has the same figure as zone 1. As it is illustrated in graph 5—1. Based on the "Cask Principle", the maximum capacity of a cask depends on its shortest batten, it can be derived that the control eccentricity radius is about 149μ. In order to cut down the control on eccentricity, two control schemes have been brought forward by experimental. A. The method of appropriate move for the center of orbit location, Ls. As it is illustrated in graph 5—4, the Ls could be moved east for 0.004651°, therefore the eccentricity control sector 2 could symmetrically be 0.01318°, and the radius for the minimum eccentricity control round could be extented to 230μcorrespondingly. B. If it is adopted that whenever the satellite excurses at western area, a AV amendment needs to be done. That means the eastern eccentricity semi-oscillation sector 0.01783°could be fully used. So radius of eccentricity control round could be widened to 230μcorrespondingly.