1. Class 5 note
Computer Network
ID:173462589
How many network cables used in communication systems?
Ans: Three major types of network cable used in communication system.
โข Fiber optic cable
โข Twisted pair cable
โข Coaxial cable
What is Fiber optic cable?
Ans: A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an
electrical cable, but containing one or more optical fibers that are used to carry light.
There are three types of fiber optic cable commonly used:
โข Single mode
โข Multi-mode
โข Plastic optical fiber (POF)
Single mode:
Single Mode fiber optic cable has a small diametral core that allows only one mode of light to
propagate. Because of this, the number of light reflections created as the light passes through the
core decreases, lowering attenuation and creating the ability for the signal to travel further. This
application is typically used in long distance, higher bandwidth runs by Telcos, CATV
companies, and Colleges and Universities.
2. Multi-mode:
Multimode fiber optic cable has a large diametral core that allows multiple modes of light to
propagate. Because of this, the number of light reflections created as the light passes through the
core increases, creating the ability for more data to pass through at a given time. Because of the
high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced
over long distances. This application is typically used for short distance, data and audio/video
applications in LANs. RF broadband signals, such as what cable companies commonly use,
cannot be transmitted over multimode fiber.
Plastic optical fiber (POF):
Plastic optical fiber (POF) or polymer optical fiber is an optical fiber that is made out of
polymer. Similar to glass optical fiber, POF transmits light (for illumination or data) through the
core of the fiber.
What is Twisted pair cable?
Ans: Twisted pair cabling is a type of wiring in which two conductors of a single circuit are
twisted together for the purposes of improving electromagnetic compatibility.
There are two main types of twisted pair cables:
โข Unshielded twisted pair (UTP)
โข Shielded twisted pair (STP)
Unshielded twisted pair (UTP):
UTP stands for Unshielded Twisted Pair cable. UTP cable is a 100 ohm copper cable that
consists of 2 to 1800 unshielded twisted pairs surrounded by an outer jacket. They have no
metallic shield. This makes the cable small in diameter but unprotected against electrical
interference.
Shielded twisted pair (STP):
Shielded twisted pair is a special kind of copper telephone wiring used in some business
installations. An outer covering or shield is added to the ordinary twisted pair telephone wires;
the shield functions as a ground.
3. What is Coaxial cable?
Ans: Coaxial Cables are also referred commonly as coax or RF Cables. The main purpose of
coaxial cables is for the transmission of radio frequency signals (RF signals). There are various
reasons for which one could use a coaxial cable. Some of the more obvious purposes are:
โข Connecting radio transmitters with their antennas
โข Receivers can also be connected to their antennas via coaxial cables
โข Coaxial cables play a major role in network connectivity
โข The most common use being in the distribution of cable television to your home
What is RJ-45 pinout?
A RJ-45 connector is a modular 8 position, 8 pin connector used for terminating Cat5e or Cat6
twisted pair cable. A pinout is a specific arrangement of wires that dictate how the connector is
terminated. Straight through is the most common type of cable and is used for connecting your
computer to your network.
Difference Between Twisted pair cable, Co-axial cable and Optical fiber cable :
Characteristics Twisted pair cable Co-axial cable Optical fiber
cable
Signal transmission Takes place in the
electrical form over
the metallic
conducting wires.
Takes place in the
electrical form over
the inner conductor
of cable.
Takes place in an
optical form over a
glass fiber.
External magnetic
field
Affected due to
external magnetic
field.
External magnetic
field is less affected .
External magnetic
field is not
affected.
Cause of power Power loss due to
conduction and
radiation.
Power loss due to
conduction.
power loss due to
absorption,
scattering and
bending.
Bandwidth Twisted pair cable
has low bandwidth.
Co-axial cable has
moderately high
bandwidth.
Optical fiber cable
has very high
bandwidth.
Electromagnetic
interference(EMI)
EMI can take place. EMI is reduced to
shielding.
EMI is not
present.
4. Installation Easy installation. Fairy easy
installation.
Difficult to install.
Attenuation In twisted pair cable
has very high
attenuation.
In co-axial cable has
low attenuation.
In optical fiber
cable has very low
attenuation.
Data rate Twisted pair cable
supports low data
rate.
Moderately high data
rate.
Very high data
rate.
Noise immunity Twisted pair cable
has low noise
immunity.
Co-axial cable has
higher noise
immunity.
Optical fiber cable
has highest noise
immunity
