1. Introduction
1.1. Satellite is a space vehicle launched by human and orbit the earth
1.2. Satellite communication is a system in which and earth station transmit radio waves via antenna to a communication satellite that has been put into the orbit
1.2.1. 1) Space segment: contain one or several active and spare satellite organize in a constellation
1.2.2. 2) Control segment: consist of all ground facilities for the control and monitoring satellite on traffic and on board resource
1.2.3. 3) Ground segment: consist of all traffic earth station depending on the type of service
2. Satellite orbit
2.1. Path followed by a satellite is called an orbit
2.2. Types of orbit rotation
2.2.1. 1) Prograde: rotate same direction as the earth (0 to 90 degrees)
2.2.2. 2) Retrograde: rotate opposite direction from the earth (90 to 180 degrees)
2.3. Types of orbital path
2.3.1. 1) Equatorial (0 degrees)
2.3.2. 2) Polar (90 degrees)
2.3.3. 3) Incline (0 to 180 degrees)
2.4. Types of orbit
2.4.1. 1) LEO (Low earth orbit)
2.4.1.1. Characteristics - 150 KM to 1500 KM - 66 satellite - Period around the earth (1.5 to 2.1 hours)
2.4.1.2. Advantages 1) Less require power 2) Frequency reuse 3) Low launch cost
2.4.1.3. Disadvantages 1) Shorter life span 2) Atmospheric drag 3) Frequent handover
2.4.1.4. Application 1) Observation 2) Weather 3) Search and Rescue
2.4.2. 2) MEO (Medium earth orbit)
2.4.2.1. Characteristics 2000 KM to 25000 KM - 25 satellite - Period around the earth (2.1 to 15.1 hours)
2.4.2.2. Advantages 1) Wider footprint 2) Fewer satellites needed 3) Less propagation delay
2.4.2.3. Disadvantages 1) More satellite than LEO 2) Greater delay than LEO 3) Higher launched cost than LEO
2.4.2.4. Application 1) Observation 2) Navigation and GPS 3) Mobile communication
2.4.3. 3) GEO (Geostationary orbit)
2.4.3.1. Characteristic -35000 KM - 3 satellite - Period around the earth (24 hours)
2.4.3.2. Advantages 1) Can cover the entire world with 3 satellites only 2) Constant view of area (24 hours) 3) Good for broadcasting
2.4.3.3. Disadvantages 1) Cannot cover high latitude or low elevations 2) Large propagation delay 3) Higher launched cost
2.4.3.4. Application 1) Broadcasting 2) Mobile service 3) Weather observation
3. Spectrum allocation
3.1. Factors in choosing a frequency in satellite link design: 1) Antenna dimension 2) Propagation factors: Rain cause a significant attenuation above 10GHz. 3) Availability allocation of slot. 4) Equipment availability 5) Cost
4. Satellite system
4.1. Uplink The path of satellite from the earth tx to satellite rx. . . . . . . : : : : : : : . . . .
4.2. Downlink The path of satellite from the satellite tx to earth rx. . . .. . . : : : : : : : . . . .
4.3. Transponder = satellite . . . . . . : : : : : : : . . . .
4.4. Satellite Subsystem
4.4.1. 1) Power Supply -Obtained from solar panel
4.4.2. 2) Altitude Control -To ensure that directional antennas point in the proper direction.
4.4.3. 3) Station Keeping -For GEO satellite to be kept in its correct orbital slot.
4.4.4. 4) Thermal Control - Use thermal blanket and shields to provide insulation.
4.4.5. 5) Telemetry, Tracking and Command (TT&C) - Monitor the satellite's health
4.4.6. 6) Antenna subsystem - a medium to receive and transmit signal
4.4.7. 7) Communication Subsystem - transponder - series interconnected units which forms a single comm channel between the rx and tx antennas in a communication satellite.