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Satellite Technology

Satellite Technology. Assoc. Prof Dr Syed Idris Syed Hassan School of Electrical and Electronic Eng Universiti Sains Malaysia Seri Iskandar , 31750 Perak. Concept. Transponder. downlink. downlink. uplink. uplink. IRRADIUM. Earth station(site B). Earth station (site A).

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Satellite Technology

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  1. Satellite Technology • Assoc. Prof Dr Syed Idris Syed Hassan • School of Electrical and Electronic Eng • Universiti Sains Malaysia • Seri Iskandar , 31750 Perak

  2. Concept Transponder downlink downlink uplink uplink IRRADIUM Earth station(site B) Earth station (site A)

  3. Communication (truncking call) Teleconference Telemedicine TV Broadcasting Data communication Telemetry(TEC, remote sensing etc) Weather telecast Navigation GPS Security/Calamity monitoring Standard Time military Applications

  4. Type of Satellites • LEO -Low Earth orbital 100-16,000Km (90min to 12hrs orbiting the earth) • MEO - Medium Earth Orbital 16,000-36,000 Km (12 - 24 hrs orbiting the earth) • GEO - Geosynchronous Earth Orbital - 36,000 Km ( The satellite appears to be stationary over one point on earth)

  5. Look angle (Elevation) El

  6. continue • Le = Earth station Latitude • le = Earth station longitude • Ls = Satellite latitude ( = 0 for GEO) • ls = Satellite longitude • rs = Satellite orbital radius ( ~ 36,000 km for GEO) • re = earth radius = 6370 km For GEO satellite

  7. Looking angle(azimuth) N • Consider for GEO only W ES E a S Sat

  8. continue • If Earth station is in the North Latitude , the azimuth will be as follow (refer to N)

  9. continue • If the Earth station is in the South latitude , the azimuth will be (refer to N)

  10. Example

  11. Link budget Noise Power Budget for 54 MHz channel Boltzmann’s Constant = - 228.6 dBW/K/Hz Receiving system noise temp. = 28.5 dBK Ku- Band ‘s channel bandwidth = 77.3 dB Receiving noise level - 122.8 dB For C/N about 10 dB to allow rain and other fading the signal level should be -112.8 dB

  12. continue

  13. continue In decibel

  14. Continue • Parabolic antenna diameter

  15. Continue • MEASAT

  16. continue • JCSAT

  17. continue • Superbird C

  18. Teleconference System 1.536Mbps Transceiver QPSK mod & demod LNA/HPA TV monitor CODEC ODU IDU

  19. Data communication 1.536Mbps PC Transceiver QPSK mod & demod LNA/HPA Router & Transciever IDU ODU

  20. Other factors need to consider • Antenna • Rain attenuation • Beam Footprint • Mismatch losses • Misalignment • Scintillation ~for low elevation • troposphere/atmosphere • Bit error rate

  21. Rain attenuation % of time exceedance 1% 0.1% 0.01% mm/hr 20 40 60 80 100 rain rate

  22. Continue • For TV and broadcasting usually the reliability is not very critical , so 99% is okay and this equivalent to 1% of exceedance of time • For data other digital com the reliability of 99.99% is probably chosen and this is equivalent to 0.01% of exceedance of time.

  23. continue For 99.99% reliability, the attenuation is calculated as where a and b are constants relied on frequency R0.01 rain rate at 0.01% of exceedance of time Lpath is slant path where signal passed the rain

  24. Slant path Rain height ~3km Lpath

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