CME 574 Satellite Communications
Fall, 2007 Dr Hazem Al-Otum Ref. Ellwood Brem, Instructor
To orbit the Earth is to fall down and miss the ground ! Topics we will cover:
• History • Earth Segment • Satellite Mechanics • Link Budget • Orbital Mechanics • Multiple Accessing • Launch Vehicles • Satellite Services: • Space Segment • VSAT, MSAT, GPS… It wasn’t easy! It wasn’t easy! http://webphysics.ph.msstate.edu/javamirror/ntnujava/projectileOrbit/projectileOrbit .html Historical Background
• 1945 Arthur C. Clarke publishes an essay about „Extra
Terrestrial Relays“
• 1957 first satellite SPUTNIK
• 1960 first reflecting communication satellite ECHO
• 1963 first geostationary satellite SYNCOM
• 1982 first mobile satellite telephone system INMARSAT-A Historical Background
• 1988 first satellite system for mobile phones and data communication INMARSAT-C
• 1993 first digital satellite telephone system
• 1998 global satellite systems for small mobile phones Historical Background Passive Sats
• Moon: (1954-62) USA Navy TX the first message Earth-moon-earth. • (1956)-Relay established between WD and Hawaii Historical Background Passive Sats
Echo: (1960) 100ft-diameter balloon Historical Background Then Came: Sputnik 1, Explorer1
• Launched October 14, 1957 – from the Baikonur Cosmodrome in Kazakhstan • 184 pounds • Orbital period 90 minutes • Broadcast “beep beep” – 20 and 40 MHz • Shocked the US into action – Started space race Historical Background Active Sats
• (1960) USA Courier – First transponder-Type Sat. (3W) • (1963-64) – USA Syncom-III attempt to place a GEO Sat. • (1965) – IntelSat 1 (Early Bird) 480 VB + 1 TV Now: Boeing 702 DBS Satellite
• 134.5 feet long • 2645 lbs payload • 11,464 lbs takeoff weight • Over 100 high-power transponders (94 active/24 spare) • Up to 25 kW power • Xenon-Ion Propulsion System Satellite Regions Utilization: 24% - USA; 13%-UK; 6% France
• Region 1: Europe, Africa, Former Sov. Union & Mongolia
• Region II: North, South America and Greenland P
• Region III: Asia, Australia, South and West Pacific Uses of Satellites (in somewhat chronological order)
• Intercontinental telephone, • Mobile satellite services data, and video (Inmarsat) • Photo Reconnaissance • Satellite radiolocation • Scientific research (GPS/Glonass) • Network TV distribution • Direct broadcast satellite • Private multipoint data (DBS – networking (VSATs) Primestar/Echostar) • Strategic military • Handheld voice/data communications communications (Iridium/ICO/Globalstar) • Signals intelligence • Internet backbone services A Platform in Space !
• In 1945 Arthur C. Clarke wrote an article in Wireless World magazine outlining a system of geo-stationary broadcast satellites in orbit 22,000 miles above the equator.
• The proverbial Sky Hook ! Intercontinental telephone, data, and video relay
• Initially satellite links were only: – One-way video and data traffic – Backup to undersea telephone cables
• Because: – Nominal 1-2 second time delay for a round-trip voice message. Imagery Reconnaissance
• Military saw the value ! – Over-fly enemy – Early “scientific” satellite programs were cover stories – Discoverer “scientific” satellites • carried cameras • returned exposed film by a parachute • Modern systems digitally encode imagery – Radio transmission to earth. • Newer systems include radar imaging • Low Earth Orbit (LEO) - typically 200 miles Scientific research
• First, scientific satellites – Space environment near earth – Unexpected discovery - Van Allen radiation belts in 1958 • Later, scientific satellites took pictures of earth – Based on military reconnaissance systems –