Satellites Adam Friedrichsen Collin Frierson Jeremy Gragg

Introduction Collin Frierson –Business MIS, Economics, Psychology –Server Support Group (OSU) Adam Friedrichsen –Business MIS, AFROTC –OSU Desktop Support Jeremy Gragg –Business MIS & Int. Bus., Computer Sci. –BSG, Sigma Phi Epsilon

Overview History Transmission Orbits Military Applications Commercial Applications Cost Forward Error Correction

History Sputnik 1 – USSR –Oct 4 57’ – Jan 3 58’ Explorer 1 - USA – Jan 31 58’ – March 31 70’ Technology grew from the Space Race Commercial and Military Applications

History Source PayloadsDebris On Orbit DecayedTotalOn Orbit Decaye d Total All3,1632,7375,9008,03016,86524,895 All On OrbitDecayedTotal 11,19319,60230,795

Transmission - Uplink Uplink facilities transmit the original signal to the satellite. Antennas are pointed at specific satellites to transmit. Frequency ranges, specific satellites tune into specific frequencies.

Transmission – Relay Satellites receive transmissions from the uplink station. Based on the signal frequency, the satellite relays and rebroadcasts the signal on another frequency.

Transmission – Downlink All Satellite receivers are tuned to specific frequencies. Most receivers need LoS (line of sight). Receivers can be large (TV Dish) or small (XM Radio Receiver).

Transmission Frequencies BANDUP-LINK (GHz)DOWN-LINK (GHz)ISSUES C Interference with ground links. Ku Attenuation due to rain. Ka High equipment cost. L/S Interference with ISM band.

LEO – Low Earth Orbit Altitude: miles –Little, Big, Mega –All Shuttle Flights Plane: Varies –Sun-Synchronous Capability Period: 90 minutes – 3 Hours –Approximate Speed: 17,000 mph

LEO – Low Earth Orbit Advantages: –Low Transmission Delay –Smaller Receiver Requirement Disadvantages: –Shorter Life –Smaller Coverage Area

MEO – Medium Earth Orbit Altitude: approx. 22,239 miles –GPS, GLONASS Constellations Plane: Varies –Sun-Synchronous Capability Period: 2 – 12 Hours

GEO – Geosynchronous Earth Orbit Altitude: Approximately 22,240 miles –Weather, Telecommunications Relays Plane: Equatorial or Polar Period: 24 Hours

GEO – Geosynchronous Earth Orbit Hohmann Transfer Geostationary Transfer Orbits

Supersnychronous/Graveyard Orbit Above Geosynchronous Orbit Used for Storage and Dead Objects

Military Applications Intelligence Gathering Battlefield Weather Communications Uplinks GPS – Navigation + Targeting

Anti-Satellite Warfare Possessed Capability to Shoot Down LEOs Since Late 1950s F-15 ASATs Since mid-1980s ASM-135 ASAT F-15 Eagle

Other Applications GPS Technology –Owned by GM –Pinpoints specific location of vehicles. XM & Sirius Radio –Recently Merged –Transmit exclusive radio content while maintaining excellent sound quality. –Reaches locations traditional radio signals cannot.

Other Applications Internet Communications –Requires Southern Sky Line of Sight –Now reasonably fast, cheap and reliable ($50 for 1.5Mbps/256 kbps) Weather Satellites –GOES-8 –Monitors weather patterns, fires, and other environmental changes.

Cost of Satellites Being sent into orbit –Construction, Liftoff & Maintenance Costs –Approximately $ million –Shuttle missions can carry several satellites into orbit. –Crashes and other problems Cost Comparisons –Relative to other transmission media. –Benefits vast geographic separation

Hamming Code Forward Error Correction –Parity Bit based error detection and correction. –Can correct single bit errors but only detect multiple bit errors. –Even and Odd parity schemes. Example Data is sent as “1011” with parity bits applied. By checking the parity, we can determine if an error occurred:

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