Satellite Technology

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Satellite Technology

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

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

• Communication (truncking call)
• Teleconference
• Telemedicine
• TV Broadcasting
• Data communication
• Telemetry(TEC, remote sensing etc)

• Weather telecast
• Navigation
• GPS
• Security/Calamity monitoring
• Standard Time
• military

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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)

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Look angle (Elevation)
El
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• 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

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Looking angle(azimuth)
N

• Consider for GEO only

W
ES
E
a
S
Sat
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• If Earth station is in the North Latitude ,
• the azimuth will be as follow (refer to N)

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

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Example
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Link budget

• Noise Power Budget for 54 MHz channel
• Boltzmanns 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

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• In decibel

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• Parabolic antenna diameter

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• MEASAT

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• JCSAT

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• Superbird C

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Teleconference System
1.536Mbps
LNA/HPA
Transceiver QPSK mod demod
TV monitor
CODEC
ODU
IDU
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Data communication
1.536Mbps
PC
LNA/HPA
Transceiver QPSK mod demod
Router Transciever
IDU
ODU
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Other factors need to consider

• Antenna
• Rain attenuation
• Beam Footprint
• Mismatch losses
• Misalignment
• Scintillation for low elevation
• troposphere/atmosphere
• Bit error rate

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

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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
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Slant path
Rain height 3km
Lpath
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