卫星通信基础知识86738.doc

Who am I?卫星通信技术/Satcom ｛卫星通信基础/Satcom ABC通信卫星资源/Comsat resource卫星通信网/Network链路设计/Link budget建站开通/Installation干扰与异常 /Interference降雨衰耗/Rain atten工作频段/Freq bands轨位协调/Coordination中国广播卫 星/China DBS常用数据表/Tables友情参-M/Visitors area｝技术文章/Articles科技译文 /Translations 其他作品/Others 生命的延续/My family 卫星通信基础/ Satcom ABC 静止卫星 / GSO satellite 卫星通信的历史与现况 / Satellite, the past and the present *卫星通信的特点/ Properties of satcom 卫星通信的分类 / Classifications for satcom *常用工作频段 *常用极化方式 *频率极化计划与通信转发器 *分贝的概念 *传输损耗 *面反射天线 *转发器的主要参数 *1/0关系曲线与功率回退 *有关论文 静止卫星 / GSO satellite ?静止卫星工作在位于赤道平面的圆轨道上，卫星的运行周期为24小时。由于静止的运转方 向和角速度与地球的口转方向和角速度相同，卫星的空间位置与地而任意地点的相对空间关 系固定不变。 GSO satellites arc locating and operating at geostationary orbit. Geostationary orbit is a circular one, with its revolution period of 24 hours. A GSO satellite appears stationary above the earth, because of its running direction and orbital velocity is as same as the earths rotational directi on and speed respectively. Therefore, an earth station could point to the satellite at fixed elevation and azimuth angles. 由静止卫星的轨道位置示意图可见，地球的平均半径约为6378公里，静止卫星的轨道高度 约为35786公里，轨道半径约为42,164公里。从静止卫星看地球，地球的角直径约为17.4 度。 As the sketch map of geostationary orbit shown, the earths mean radius is about 6378 km, while the altitude and orbit radius of a GSO satellite is approximately equal to 35786 km and 42164 km respectively. Looking from a GSO satellite, the earths diameter is about 17.4o in angle. 在采用EquiRectcngular投影方式的静止卫星的覆盖范围示意图中，三条绿线分别对应东经 105.5度卫星的0度、15度、及30度仰角服务区。图中的0度仰角服务区表明，静止卫星 只能覆盖到南北纬大约80度处，南北两极附近的高纬度地区并不在静止卫星的服务区内。 由15度仰角服务区的经度覆盖范围大致有140度町知，只需轨位间隔约为120度的三颗静 止卫星，就可以覆盖南北纬70度以下的绝人部分地球表面。 Adopting EquiRectengular projection method, the sketch map of the coverage of a GSO satellite located in 105.5oE longitude presents three green lines denoting service areas of elevation Oo, 15o and 30o respectively. The service area of Oo elevation indicates that a GSO satellite could only cover the area between 8O0N and 8O0S latitude, while higher latitude areas near no