Lab 1
By
Mehran Mamonai
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A satellite is a radiofrequency repeater but
New-generation satellites are regenerative.
Satellite amplify, conditions and reformat
received (uplink) data and route (downlink)
the data to specified locations.
Reformatting is done in Transponder.
Satellite moves in different orbits.
Satellite has vast number of Applications.
Limitation in Satellite.
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U.S.S.R.’s launch of the first artificial satellite
called Sputnik (1957).
Worked only for 21 days as Telemetry
services.
The first series of commercial geostationary
satellites was inaugurated in 1965
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High Frequency Radio waves were used as
carriers of information with a large
bandwidth
Earth to Satellite Frequency is called Uplink
Satellite to Earth Frequency is called
Downlink
Reception area called footprint (covering
map)
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Transmitter and Responder = Transponder
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The satellites are characterized by the power
they radiate in the beam axis
This corresponds to the power (expressed in
dBW)
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Geostationary satellite (GEO)
High elliptical orbiting satellite (HEO)
Middle-earth orbiting satellite (MEO)
Low-earth-orbiting satellite (LEO)
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All satellite occupies an orbit around the
ground located at about 36,000 km (35785)
height
satellite speed coincides to the earth rotation
speed.
Also called Geosyncronous.
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An HEO satellite is a specialized orbit
satellite continuously swings very close to the
earth, loops out into space, and then repeats
It is an elliptical orbit approximately 18,000 to
35,000 km above the earth’s surface
Not necessarily above the equator
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Satellite orbiting approximately 8,000 to
18,000 km above the earth’s surface
Not necessarily above the equator
between the LEO and GEO
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Orbit between altitude of approximately
160km to 2,000 kilometers
Majority of artificial satellites, have been in
LEO.
Satellite cannot orbit less than 300 km due to
the larger atmospheric drag.
Lowest Delay then orbit MEO and GEO.
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C – band
 Up-link: from about 5.7GHz to about 6.5GHz
 Down-link: from 3.4GHz to 4.2GHz
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Ku – band:
 Up-link: from about 14GHz to about 14.5GHz
 Down-link: from 10.95GHz to about 12.75GHz, with the
following sub-division:
 10.95 – 11.70GHz FSS band (Fixed Satellite Services) for TV
communication
 11.70 – 12.50GHz DBS band (Direct Broadcasting Satellite)
for direct diffusion
 12.50 – 12.75GHz SMS band (Satellite Mobile Services)
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More channels on the same band
Polarity formats
 Linear
▪ Horizontal
▪ Vertical
 Circular
▪ LHCP
▪ RHCP
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Frequency modulated by the Video + Audio
composite signal
PAL
NTSC
SECAM
MAC
 Superior clearness of the digital superior to the
50% in respect to PAL
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Employs the QPSK digital modulation