PLCC AND SATELLITE COMMUNICATION

1. PLCC POWER LINE
CARRIER COMMUNICATION
VS SATELLITE
COMMUNICATION
Zelalem Fikadu
2k17/C&I/20

2. Power Line Carrier Communication System (PLCC)
 Plcc is the method of transmitting information using power network or line
 Its equipment are used for point-to-point communication over high voltage power
lines
 PLCC system uses the same High Voltage transmission line connecting
two sub-stations for telecommunication purpose too
 PLCC is used in all power utilities as a primary communication service to
transmit speech, telemetry and protection tripping commands. This is
economic and reliable for inter grid message transfer as well as low bit
rate RTU signals.

3. Basic Principal of plcc
 The telephone communication system cannot be directly connected to the high
voltage lines so, we use suitable designed coupling devices for communication
 These usually consist of high voltage capacitor used in conjunction with suitable
line matching unit(LMU) for matching the impedance of line to that of the coaxial
cable connecting the unit to the plc transmitter-receiver equipment.
Signal can be transmitted over the PLCC include
• speech signal (300-2000Hz) and
• data signal (2000-3000Hz)

4. Power Line Carrier Communication System

5. Components
PLCC Terminal = Translates Voice and data into High Frequency Carrier. Output
Power =10 to 80W
LMU ( Line Matching Unit) = For impedance matching between line and coaxial
cable, includes high voltage protection devices like drainage coil(20mH), lightening
arrestor(500V) and an earth switch.
Coupling Capacitor (C.C) = Couples high frequency carrier with Power Line
Line Trap (L.T) = Do not allow the transmitted HF carrier to enter inside the
substation. (L = 0.5 to 2mH) With out Line trap HF carrier get by- passed to some
other line on the same bus bar and may leak to ground ( a earth switch inside the
yard provided for each bay is kept closed during maintenance)

13. Satellite communication
Defination of satellite
 an artificial body placed in orbit round the earth or another planet in order to
collect information or for communication purpose due to the effect of mutual
gravitational forces, used for broadband communication.
 Satellite communications is the use of satellite technology in the field of
communications. The services provided by satellite communications are voice and
video calling, internet, fax, television and radio channels.
 Satellite communications can provide communication capabilities spanning long
distances and can operate under circumstances or conditions which are inoperable
for other forms of communication.

15. Types of Satellites
 Active satellite
It is one in which the signal is amplified and its frequency changed by transponder,
before it sent back to earth.
Example: communication , broadcasting satellites
 Passive satellite
These type of satellites simply reflects or scatters the
micro wave signal back to another station
Example: military and non profitable servieces

16. ELEMENTS OF SATELLITE COMMUNICATIONS
SYSTEM
Two major elements of Satellite Communications Systems are:
Space Segment
Ground Segment
The Space Segment includes:
Means for launching satellite
Satellite(Transponders)
Power supply system
The ground segment consists of:
Earth Stations
Rear Ward Communication links

17. Power requirement
 Modern satellites use a variety of power means
 Solar panels are now quite efficient, so solar power is used to generate electricity
 Batteries are needed as sometimes the satellites are behind the earth - this happens
about half the time for a LEO(Low earth orbits are satellite systems used in
telecommunication, which orbit between 400 and 1,000 miles above the earth's
surface) satellite
 Nuclear power has been used - but not recommended

18. SATELLITE COMMUNICATION SERVICES
Different Satellite Communications services are classified as
 one way link
 Two way link.
One way link from transmitter Tx to receiver Rx on earth’s
surface

19. Examples of satellite services where the transfer of
information takes place through one way link are:
 Broadcast Satellite Service (Radio, TV, Data broadcasting)
Data Collection Service (Hydro meteorological data collection)
Space operations service, (Tracking, Telemetry, Command)
Safety services (Search & Rescue, Disaster Warning)
Earth Exploration Satellite Service (Remote Sensing)
Radio Determination Satellite Service (Position location)
Reporting Service (fleet monitoring)

20. Two-way Satellite Communications link
 Fixed Satellite Service (Telephone, telex, fax, high bit rate
data etc.)
 Mobile Satellite Service (Land mobile, Maritime, Aero-mobile,
personal communications)
 Satellite News Gathering (Transportable and Portable )

21. Advantages of Satellites
The advantages of satellite communication over terrestrial communication are:
 The coverage area of a satellite greatly exceeds that of a terrestrial system.
 Transmission cost of a satellite is independent of the distance from the center of the
coverage area.
 Higher Bandwidths are available for use.
Disadvantages of Satellites
 Launching satellites into orbit is costly.
 Satellite bandwidth is gradually becoming used up.
 There is a larger propagation delay in satellite communication than in terrestrial
communication.