Introduction to satellite Communications Lecture (11) 12/24/20151Dr. Hassan Yousif

What is a satellite ? S atellite is an object launched to orbit earth or another celestial body. 12/24/20152Dr. Hassan Yousif

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How it works 12/24/2015Dr. Hassan Yousif4

Features of Satellites: Providing global coverage. Carrying large amount of traffic For satellite systems the cost is “distance insensitive” Remote sensing (pollution, weather, search and rescue) 12/24/20155Dr. Hassan Yousif

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How it launches Anything on the surface of the Earth at the equator is already moving at 1670 kilometers per hour. If you look at two spots on one line from pole to pole, one spot on the equator and the other halfway to the pole, each will make a complete revolution in 24 hours and return to where it was. But since the Earth's shape is round, and the widest point is at the equator the spot on the equator would have to go more miles in that twenty four hours. That means that the land is moving faster at the equator than any other place on the surface of the Earth. The land at the equator is moving 1670 km per hour, and land halfway to the pole is only moving 1180 km per hour, so launching from the equator makes the spacecraft move almost 500 km/hour faster once it is launched. 12/24/2015Dr. Hassan Yousif7

Applications 12/24/2015Dr. Hassan Yousif8  Traditionally – weather satellites – radio and TV broadcast satellites – military satellites – satellites for navigation and localization (e.g., GPS)  Telecommunication – global telephone connections – backbone for global networks – connections for communication in remote places or underdeveloped areas – global mobile communication –  satellite systems to extend cellular phone systems (e.g., GSM or AMPS)

Advantages of Satellites The advantages of satellite communication over terrestrial communication are:  The coverage area of a satellite greatly exceeds that of a terrestrial system.  Transmission cost of a satellite is independent of the distance from the center of the coverage area.  Satellite to Satellite communication is very precise.  Higher Bandwidths are available for use. 12/24/20159 Dr. Hassan Yousif

Disadvantages of Satellites  Launching satellites into orbit is costly.  Satellite bandwidth is gradually becoming used up.  There is a larger propagation delay in satellite communication than in terrestrial communication. 12/24/ Dr. Hassan Yousif

Satellite-Related Terms Earth Stations – antenna systems on or near earth Uplink – transmission from an earth station to a satellite Downlink – transmission from a satellite to an earth station Transponder – electronics in the satellite that convert uplink signals to downlink signals 12/24/ Dr. Hassan Yousif

Satellite System Elements 12 Space Segment Satellite TT&C Ground Station Ground Segment Earth Stations Coverage Region SCC 12/24/2015 Dr. Hassan Yousif

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Space Segment –Satellite Launching Phase –Transfer Orbit Phase –Deployment –Operation – TT&C - Tracking Telemetry and Command Station – SSC - Satellite Control Center: –OCC - Operations Control Center –SCF - Satellite Control Facility Provides link signal monitoring for Link Maintenance and Interference monitoring. –Retirement Phase 1412/24/2015 Dr. Hassan Yousif

Satellite Subsystems Communications – Antennas – Transponders Common Subsystem (Bus Subsystem) – Telemetry/Command (TT&C) – Satellite Control (antenna pointing, attitude) – Propulsion – Electrical Power – Structure – Thermal Control 1512/24/2015 Dr. Hassan Yousif

Satellite Services  Fixed Service Satellites (FSS) Example: telephone system, Sat to Cable  Broadcast Service Satellites (BSS) Example: Satellite Television/Radio Also called Direct Broadcast Service (DBS). In Europe called DTH  Mobile Service Satellites (MSS) Include land mobile, maritime mobile, and aeronautical mobile.  Navigational satellite services i.e. GPS  Meteorological satellite services i.e. Weather and rescue service 1612/24/2015 Dr. Hassan Yousif

Frequency Allocations for Satellite Services To facilitate frequency planning, the world is divided into three regions:  Region 1: Europe, Africa  Region 2: North and South America and Greenland  Region 3: Asia, Australia, and the southwest Pacific 1712/24/2015 Dr. Hassan Yousif

Intelsat 10 at 68.5º E Africa footprint. 1812/24/2015 Dr. Hassan Yousif

Telestar 12 footprint 1912/24/2015 Dr. Hassan Yousif

NileSat footprint 2012/24/2015 Dr. Hassan Yousif

Services provided by satellites: Fixed satellite service (FSS), telephone network Broadcasting satellite service (BSS ), DTH Mobile satellite services ( MSS), land, maritime Navigational satellite services (NSS), GPS Meteorological satellite services (MSS), SARS 12/24/ Dr. Hassan Yousif

Frequency band designations 12/24/2015Dr. Hassan Yousif22 Frequency range (GHz) BandService Band 0.1 – 0.3 VHF Navigation/ Weather 18 – 27 K 0.3 – 1 UHF 27 – 40 Ka 1 – 2 LMobile 40 – 75 V 2 – 4 S 75 – 110 W 4 – 8 CFSS mm X μmμmμmμm 12 – 18 Ku DBS/ FSS

ITU Frequency Band Designation Frequency range band name  Frequency range band name 3-30 KHz VLF MHz VHF KHz LF MHz UHF KHz MF 3-30 GHz SHF 3-30 MHz HF GHz EHF 12/24/201523Dr. Hassan Yousif

12/24/ Intelsat V Dr. Hassan Yousif

12/24/ Intelsat VI Dr. Hassan Yousif

12/24/ An Earth Observation Sat (EOS) Dr. Hassan Yousif

12/24/ A communication sat. Dr. Hassan Yousif

12/24/ Important Terminologies 1.Apogee (point of farthest approach) 2.Perigee (point of closest approach) 3.Line of Apsides 4.Ascending node 5.Descending node 6.Line of nodes 7.inclination Dr. Hassan Yousif

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12/24/ Apogee & Perigee heights The Length of the radius vectors at the apogee and perigee: r a = a (1 + e) r p = a (1 - e) Dr. Hassan Yousif

12/24/ Example (2-1) Calculate the apogee and perigee heights for a satellite orbit, given that e = a= Km. Assume that the mean earth radius is 6371 Km. Dr. Hassan Yousif

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Types of Satellites: INTELSAT (international Telecom. Satellite) GEO, AOR+IOR+POR+IAR DOMSAT (domestic Satellite) GEO Polar Orbiting Satellites Sun synchronous, ascending pass, descending pass 12/24/201534Dr. Hassan Yousif

The evolution of Intelsat satellite Early bird Intelsat V Intelsat VI Intelsat VII First Launch Satellite mass in orbit (kg) Prime Power (W) Number of transponders Total Bandwidth (MHz) Telephone Channel capacity: All Analog All Digital , , ,000 12/24/201535Dr. Hassan Yousif