UNIT 17 Satellite Communication Systems,This unit is mainly discuss the basic knowledge about “Satellite Communication Systems ”. A basic Satellite Systems construction The frequency spectrum utilized by satellite Communication Systems,NEW WORDS:,1. schematically ski mtikli adv. 图示地, 用示意图, 用图解法 schematic adj. 纲要的, 示意的, 概略的; 计划性的 图解的, (按照)图式公式的 schematic diagram 示意图 【词性变化】 schematic n. 简图(如电路图); 示意图, 原理图, 图解 cable-and -trunk schematic 【电】电缆和干线简图 2. baseband beisbnd n. 基带 base+band,3. dedicated dedikeitid adj. 专用的;热诚的，一心一意的 dedicate vt.专门用于;献给, 献身, 致力 ; 【习惯用语】 be dedicated to. 献身于. dedicate oneself to. 献身于. dedicate ones life to. 献身于. dedicate . to sb. 把(作品)奉献给某人 4. spectrum spektrm n. 光谱, 频谱 a solar spectrum 太阳光谱 spectrum analysis 光谱分析 5. retransmit ri:trnzmit v.转发, 中继站发送,5. retransmit ri:trnzmit v. 转发, 中继站发送 re-再；重新 6. commercial km:l adj. 商业的, 贸易的 【词性变化】 commercial n. (无线电或)电视中的 广告节目 【继承用法】 commercialism n. 商业主义，商业精神，商业习惯； commercialist n. 商业家， 商业主义者； 营利主义者 7. utilize ju:tilaiz vt. 利用 同义词 employ use safety measures in utilizing electric 用电安全措施,8. geostationary i(:)usteinri adj.与地球同步的 geostationary orbit (人造卫星的)对地静止轨道 9. congest knest vt. 充塞, 拥挤 eg. The streets are often congested. 街上经常拥挤。 【继承用法】 congestible adj.,10. attenuate tenjueit vt. 削弱 【词性变化】 attenuate vi. 变细, 变薄, 变弱; 衰耗 attenuate adj. 稀薄的 细的, 薄的 减弱的 eg. a device that attenuates an electrical signal. 衰减器，减压器使电子讯号减弱的装置,Technical terms:,1. earth station 地面接收站, 转播站 2. dedicated line 专用线 3. Radio Frequency(RF) 无线电频率, 射频 4. uplink/downlink frequency spectrum 上行/下行频谱 5. terrestrial microwave link 地面微波链路 6. experimental stage 试验阶段,Expressions:,in order to 为了. switch on 接通 set aside 留出,Questions for text discussion:,1. Talk about the main parts in a satellite system. 2. What tasks can an earth station perform? 3. What is the function of the satellite in space?,Text:,The first paragraph: A satellite system consists basically of a satellite in space which links many earth stations on the ground, as shown schematically in Fig.1. The user generates the baseband signal which is routed to the earth station through the terrestrial network. The terrestrial network can be a telephone switch or a dedicated link to the earth station. notes: consists of: 由组成 route n. 路; 路线程; 航线 eg. the Eighth R-Army 八路军 a train bus route 火车公共汽车路线 travel from Shanghai to Dalian by the route across the sea 从上海乘海轮去大连 【词性变化】 route vt. 给.规定路线次序, 程序; 由某一路线发送 terrestrial network 地面网,The first paragraph: At the earth station the baseband signal is processed and transmitted by a modulated radio frequency (RF) carrier to the satellite. The satellite can be thought of as a large repeater in space. It receives the modulated RF carriers in its uplink (earth-to-space) frequency spectrum from all the earth station in the network, amplifies these carriers, and retransmits them back to earth in the downlink (space-to-earth)frequency spectrum in order to avoid interference（1）. notes: a modulated radio frequency(RF)carrier 已调制的射频载波 be thought of as 被看作为 repeater 中继器 amplifies （amplify) 放大 interference 干扰 Sentence 1:这是一长句的翻译，其中的receives , amplifies, retransmits 为并列谓语，而 in order to 为动词不定式短语作目的状语。,3. dedicated dedikeitid adj. 专用的;热诚的，一心一意的 dedicate vt.专门用于;献给, 献身, 致力 ; 【习惯用语】 be dedicated to. 献身于. dedicate oneself to. 献身于. dedicate ones life to. 献身于. dedicate . to sb. 把(作品)奉献给某人 4. spectrum spektrm n. 光谱, 频谱 a solar spectrum 太阳光谱 spectrum analysis 光谱分析 5. retransmit ri:trnzmit v.转发, 中继站发送,5. retransmit ri:trnzmit v. 转发, 中继站发送 re-再；重新 6. commercial km:l adj. 商业的, 贸易的 【词性变化】 commercial n. (无线电或)电视中的 广告节目 【继承用法】 commercialism n. 商业主义，商业精神，商业习惯； commercialist n. 商业家， 商业主义者； 营利主义者 7. utilize ju:tilaiz vt. 利用 同义词 employ use safety measures in utilizing electric 用电安全措施,8. geostationary i(:)usteinri adj.与地球同步的 geostationary orbit (人造卫星的)对地静止轨道 9. congest knest vt. 充塞, 拥挤 eg. The streets are often congested. 街上经常拥挤。 【继承用法】 congestible adj.,10. attenuate tenjueit vt. 削弱 【词性变化】 attenuate vi. 变细, 变薄, 变弱; 衰耗 attenuate adj. 稀薄的 细的, 薄的 减弱的 eg. a device that attenuates an electrical signal. 衰减器，减压器使电子讯号减弱的装置,Technical terms:,1. earth station 地面接收站, 转播站 2. dedicated line 专用线 3. Radio Frequency(RF) 无线电频率, 射频 4. uplink/downlink frequency spectrum 上行/下行频谱 5. terrestrial microwave link 地面微波链路 6. experimental stage 试验阶段,Expressions:,in order to 为了. switch on 接通 set aside 留出,Questions for text discussion:,1. Talk about the main parts in a satellite system. 2. What tasks can an earth station perform? 3. What is the function of the satellite in space?,Text:,The first paragraph: A satellite system consists basically of a satellite in space which links many earth stations on the ground, as shown schematically in Fig.1. The user generates the baseband sign