1) A satellite communication system consists of a communication satellite in orbit that receives and amplifies signals and redirects them, a ground-based control station, and earth stations for transmission and reception. 2) Satellites receive signals from earth stations, amplify and translate frequencies, and broadcast to other earth stations. Signals travel from an earth station to the satellite and back to another earth station. 3) Satellite transponders act as repeaters with receivers and transmitters, picking up signals from earth, amplifying them, translating frequencies, and retransmitting to earth.

1. SATELITE
COMMUNICATION
SYSTEM
NAME :
MOHAMAD HELMY BIN RAMLAN
ZULHAZMI HARITH B. NAWIR
MOHD TARMIZI BIN ZAKARIA
AMIRUL SYAFIQ

2. INTRODUCTION TO SATELITE COMMUNICATION
SYSTEM
A communication satelite is a radio relay station in orbit above
the earth that receives, amplifies and redirects analog signals
carried on a specific radio frequency.
A satelite system consists of:
I. A transponder ( a radio repeater in the sky)
II. A ground-based station to control its operation
III. A user network of earth stations that provide the facilities for transmisson
reception of communication traffics through the satelite system.

3.  Satelite receive a signal from the ground station, do the
amplification and frequency translation, and broadcast
it to earth stations that are able to receive transmission.
 A satelite begins at a single earth stations, passes
through the satellite, and ends at one or more earth
stations.
 A satelite communication systems utilize microwave
terminals both on satelite and in earth stations for high
reliable and high-capacity system.

4. SATELITE TRANSPONDER
Satelite transponder acts like a repeater, consists of a receiver
and a transmitter. The main function of a satelite transponder
are:
 To pick up the transmitted signal from the transmitter on the earth
 To amplify the signal
 To convert the carrier frequency to another frequency
 To retransmit the amplified signal to the receiver on the earth

5. 5.3.3 Satellite system links
 In telecommunications, a link is a
communication channel that connects
two or more communicating devices.

6. Uplink
 Path of satellite
signal from earth
transmitter to satellite
receiver.
 The frequency signal
being transmitted
from the earth
station to the
satellite.
 C-band = 6 GHz
Downlink
 Path of the satellite
signal from the satellite
transmitter to the
receiver on earth.
 It occurred when the
retransmitted signal
from the satellite to the
receiving stations.
 C-band = 4 GHz

7. 5.3.4 Earth station
 Block diagram of an earth station
transmitter.

8.  Modulator= converts the input baseband
signals to an FM,PSK or QAM modulated
frequency.
 Up-Converter = converts the intermediate
frequency (IF) to an appropriate (RF)
carrier frequency.
 High power amplifier (HPA) =provides
adequate input sensitivity and output
power to propagate the signal to the
satellite transponder.

9.  Block diagram of an earth station
receiver.

10.  Low noise amplifier (LNA)=amplifies the
received signal.
 Down converter = converts the received
RF signal to an IF.
 Demodulator = detects the information
signal and send to the appropriate
baseband outputs.

11. FREQUENCY ALLOCATIONS
BAND FREQUENCY BAND (GHz)
VHF 0.03 - 0.3
UHF 0.3 – 3
L 1 – 2
S 2 – 4
C 4 – 8
X 8 – 12
Ku 12 – 18
K 18 -27
Ka 27 – 40
V 40 – 75
W 75 – 100
mm band 110 - 300

12. SATELLITE ORBIT
 Polar Orbit
 Elliptically Inclined OrbitEccentric Orbits
 Circular Equatorial OrbitGeostationary
Orbits

13. POLAR ORBIT:
 North-south orbit
 Used for navigation, weather satellites,
meteorological and land resource satellite system.
 Not used for telecommunication purposes.

14. ELLIPTICALLY INCLINED ORBIT :
 Used for Russian domestic systems, with
inclanation of 63 𝑜 and a 12 hour orbit
period but only visible for 8 hours.
 For a continuous coverage in a day, 3
satellites are need.

15. CIRCULAR EQUATORIAL ORBIT
 Also known as geosynchronous orbit.
 The satellites are at height of about 35800km,
has 24 hour orbit period and angular speed
that equal to the rotational speed of the
earth.(it will become stationary)
 3 satellites are used to cover up the whole
surface of the earth because a satellite can
only be visible to 1/3 of the earth surface.

16. ADVANTAGES OF
GEOSYNCHRONOUS SATELLITES:
 Computer-controlled tracking of the satellite can
be minimized when the satellite remain almost
stationary with the earth station.
 A geosynchronous satellite is permanently in view
which mean there is no breaks in transmission so, no
need to switch one satellites to another.
 Due to high altitude(35800km from earth), it can
cover a large area on earth(about 1/3 of the earth)
so more earth stations may intercommunicate.
 The effect of Doppler shift are negligible. Doppler
shift is the change in the apparents frequency of
the radiation to and from the satellite cause by the
motion of the satellites to and from the earth
station.

17. DISADVANTAGES OF
GEOSYNCHRONOUS
SATELLITES:
 Latitude greater than 81.25 𝑜 North and
South are not covered.
 Due to the high latitude, the received
signal power are very weak and the signal
propagation delay is about 300 msec

18.  Weather satellite : Provide meteorologist with
scientific data and prediction of weather
conditions
 Earth Observation satellites : Allows scientist to
gather information about earth’s ecosystem
 Navigation satellites : Using GPS technology to
provide building exact location .
 Digital Audio broadcasting .
 Vehicle tracking .
 Mobile communications
 Satellite internet
Applications of satellite
communication

19. Advantages of Satellite System
 It can access wide geographical area.
 Wide bandwidth.
 High reliability.
 Distance insensitive cost.
 Rapid installation
 Uniform service characteristic.
Comparison between satellite system
and terrestrial microwave system

20. Disadvantages of satellite communication
 High initial cost.
 Satellite is far away from earth.
 Satellite communication phones cant work when
you are inside building.
 Regulatory licensing requirement and limited orbital
parking slot.