| Since 70's of 20th century,the use of satellite on Radio and TV transmission has been put on concern by many countries worldwide. The satellite transmission of Radio and TV with the advantages of wide coverage, long transmission distance, huge information volume, high quality of signal and unaffected by geographical constraints, etc, has been rapidly developed and widely used in China's Radio and TV Industry recent years. However, satellite transmission is a open transparent system, the uplink area of signal is vast, the program frequency and the symbol rate are publicly parameters, vulnerable to space or ground non-malware interference or malicious attacks. Since 2002, the numbers of attacks by overseas lawbreakers has increased year by year with various means, especially they are equipped with the high power amplifier and large aperture antenna, which are serious threat to the normal broadcasting of China's Satellite Radio and TV programmes.To integrate satellite resources, enhance the quality of signal transmission, improve rating effect and thoroughly solve the problems such as unlawful interference, China invested 5 billion in 2006 to build two special satellites Sinosat-3 (125°E)and Chinasat-6B (115.5°E),which were successfully launched respectively on June 1st,2007 and July 5th,2007. From August 1st,2007, the programmes originally broadcasted through Apstar-2R(76.5°E) Chinastar-1(87.5°E), AsiaSat-3S(105.5°E),Sinosat-1(110.5°E),AsiaSat-4(122°E) and Apsatr-6(134°E) have been transferred to Sinosat-3(125°E) and Chinasat-6B(115.5°E). At the same time, the Radio and TV programmes originally transmissed and broadcasted through Sinosat-1(110.5°E) KU repeater have been transferred to Apstar-6(134°E)Ku frequency repeater for transmission.As the direct implementer of Satellite-Transfer task, the performance of satellite uplink station is directly related to the transmission safety of Radio and TV satellite signals. In order to achieve better results,Anhui Earth Station,in the Satellite-Transfer adjustment work, has realized:1.Adjustment of the position of TV program in Chinasat-6B repeater,avoid the excessive intermodulation interference; 2.Overall planning and allround consideration, the optimization design of the uplink signal symbol rate; 3.The scientifically design of the signal source, enhance the system reliability; 4.Reasonable design of radio-frequency signal wiring, improve the stability of the uplink output power and other uplink systems optimization design.In the implementation of the project, Anhui Earth Station has completed: 1.the adjustment of antenna feeder system; 2.the expansion and modification of surveillance wall and control table; 3.the installation and debugging of new uplink system, ensured the successfully completion of Satellite-Transfer work and made important contribution to the national receipt normally of AHTV programmes and the rapid development of AHTV business, also be the solid technical basis for the Anhui Earth Station being the one of nine "zero off-the air signal rate"stations nationwide in 2007. |
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