SatellitesSatellites OverviewHistory of SatellitesSlide 4Slide 5Slide 6How Satellites WorkSatellite Frequency Bands and Antennas (Dishes)Slide 9Low-Earth-Orbit (LEO)Little LEOs ApplicationsBig LEOs ApplicationsMega (Super) LEOs ApplicationsHubble TelescopeSpace DebrisMiddle-Earth-Orbiting (MEO)GPS: What is it ?GPS: How it worksGPS: Problems in the SystemGPS: Who Uses GPS ?Geosynchronous-Earth-Orbit (GEO)Basics of GEOsGEOs and WeatherFacts about GEOsGEOsPros and Cons of GEOsProvides images of nearly one-third of the Earth's surface every 23 minutes with 4 km resolution. While the United States maintains and operates its GEOs, the European community is served by its European Space Agency (ESA) Meteosat satellite, and Japan with its GMS satellite. Satellite Tracking SystemConclusionSlide 30SourcesSatellitesSatellitesAmy ChaAmy ChaLaura CollinsLaura CollinsBrad RobertsonBrad RobertsonSatellites OverviewSatellites OverviewHistory History How Satellites WorkHow Satellites WorkSatellite Frequency Bands and AntennasSatellite Frequency Bands and AntennasOrbit Distance, Pros & Cons, ApplicationsOrbit Distance, Pros & Cons, ApplicationsTypes: Types: Low-Earth-Orbit (LEOs)Low-Earth-Orbit (LEOs)Medium-Earth-Orbit (MEOs)Medium-Earth-Orbit (MEOs)Global Positioning System (GPS)Global Positioning System (GPS)Geostationary (GEOs)Geostationary (GEOs)Satellite Tracking System (J-Tracker, J-Pass)Satellite Tracking System (J-Tracker, J-Pass)History of SatellitesHistory of SatellitesThe First SatellitesThe theory of satellites was simple enough - shoot something out into space at the right speed and on the correct trajectory and it will stay up there, orbiting Earth, for years - if not forever. If the orbit is the right distance in space the satellite will keep pace with the rotation of the Earth. Pioneer Satellites (1957) Early in October 1957 communications stations started picking up a regular beeping noise coming from space. The signals were coming from Russia's Sputnik 1, the world's first man-made satellite. It was January 1958, before a Jupiter rocket successfully launched Explorer 1, the first American satellite.History of SatellitesHistory of SatellitesNASA's Syncom programme (1963) GEOsIn July 1963 the Hughes Aircraft Corporation launched the experimental Syncom 2 for NASA, the world's first geosynchronous communications satellite. Its earlier sister, Syncom 1, had been blown up on launch earlier that year, but the second version was a huge success. It carried the first live two-way satellite call between heads of state when President John F. Kennedy in Washington, D.C., telephoned Nigerian Prime Minister Abubaker Balewa in Africa.The third Syncom satellite transmitted live television coverage of the 1964 Olympic Games from Tokyo.History of SatellitesHistory of SatellitesEarly Bird (1965) The world's first commercial communications satellite was Early Bird, built for the Communications Satellite Corporation (COMSAT) by Hughes. The satellite was launched on April 6, 1965, and placed in commercial service after moving into geosynchronous orbit 22,300 miles above the equator. That meant it was always on station to provide line of sight communications between Europe and North America. Early Bird didn't have a battery - and worked only when its solar panels were exposed to the sun.History of SatellitesHistory of SatellitesLater communications satellites The launch of the Intelsat 3 satellites in 1969 created a global TV and speech communications network that spanned the Atlantic, Pacific and Indian Oceans. The introduction of multiple-beam antennas in the 1980s brought new improvements in efficiency, as a satellite's power could now be concentrated on small regions of the Earth, making possible smaller-aperture (coverage area), lower-cost ground stations. The Capacity (the number of simultaneous television and speech channels carried) grew as well.How Satellites WorkHow Satellites Work1.1.A Earth Station sends A Earth Station sends message in GHz range. message in GHz range. (Uplink) (Uplink) 2.2.Satellite Receive and Satellite Receive and retransmit signals back. retransmit signals back. (Downlink)(Downlink)3.3.Other Earth Stations Other Earth Stations receive message in receive message in useful strength area. useful strength area. (Footprint)(Footprint)Satellite Frequency Bands and Satellite Frequency Bands and Antennas (Dishes)Antennas (Dishes)The size of Satellite Dishes (antennas) are The size of Satellite Dishes (antennas) are related to the transmission frequency.related to the transmission frequency. There is a There is a inverse relationshipinverse relationship between between frequency and wavelength. frequency and wavelength. As wavelength increases (and frequency As wavelength increases (and frequency decreases), larger antennas (satellite dishes) decreases), larger antennas (satellite dishes) are necessary to gather the signal.are necessary to gather the signal.Satellite Frequency Bands and Satellite Frequency Bands and Antennas (Dishes)Antennas (Dishes) C-BandC-Band Ku-Band Ku-BandMost commonly used bands: Most commonly used bands: C-band C-band (4 to 8 GHz) (4 to 8 GHz) , Ku-, Ku-band band (11 to 17 GHz) , and Ka-band (20 to 30 GHz ). (11 to 17 GHz) , and Ka-band (20 to 30 GHz ).Low-Earth-Orbit (LEO)Low-Earth-Orbit (LEO)Altitude (375-1000 miles)Altitude (375-1000 miles)Revolution time: 90 min - 3 hours.Revolution time: 90 min - 3 hours.Advantages:Advantages: Reduces transmission delay Reduces transmission delay Eliminates need for bulky Eliminates need for bulky receiving equipment.receiving equipment.Disadvantages:Disadvantages: Smaller coverage area.Smaller coverage area.Shorter life span (5-8 yrs.) Shorter life span (5-8 yrs.) than GEOs (10 yrs).than GEOs (10 yrs).Subdivisions: Little, Big, and Mega Subdivisions: Little, Big, and Mega (Super) LEOs.(Super) LEOs.Little LEOs ApplicationsLittle LEOs Applications0.8 GHz range0.8 GHz rangeSmall, low-costSmall, low-costVehicle tracking, Vehicle tracking, environmental monitoring environmental monitoring and two-way data and two-way data communication. Used for communication. Used for short, narrowband short, narrowband communications. communications.Big LEOs ApplicationsBig LEOs Applications2 GHz or above range2 GHz or above rangeCan offer global services, which Can offer global services,