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Satellite network
Operation
- 케플러 법칙
- the signal from a satelllite is normally aimed to
Three Categories of Satellites
- GEO satellite: 정지 궤도 위성, 고도 에 위치해야 함.
- van allen belt is a layer that contains charged particles
- MEO
- LEO
MEO, LEO는 자전속도보다 훨씬 빠르게…
Frequency Bands for Satellite Communication
- transmission from the earth to the satellite is called uplink
- transmission from the satellite to the earth is called downlink
GEO Satellites
- Geostationary Earth Orbit (정지 궤도 위성)
- 지구 전체를 모니터링 하려면 세개를 쏘아 올려야 한다.
MEO Satellites
- Medium-Earch Orbit (MEO)
- One Example of a MEO satellite system is the Global Positioning System (GPS), 고도 18000km
GPS
- 24개의 위성, 6개의 궤도
- 한 궤도에 4개의 위성
- four satellites are visible from any point on Earth.
- GPS is based on a principle called trilateration
- On a plane,
- In space
LEO
- Low-Earth Orbit
Iridium System
- 66 satelites, orbit에 11개
Teledesic
- 288 satellites in 12 polar orbit