3. Introduction
• Telecom cables form the backbone of the
telecommunication infrastructure around the globe.
• These communication cables transmit voice
messages, computer data, and visual images via
electrical signals to telephones, wired radios,
computers and televisions.
Contd…
4. • Copper has been used in electric wiring since the
invention of the electromagnet and the telegraph in
the 1820s.
• Majority of the communication cables used copper as
a conductor.
• Optical Cables are replacing the traditional copper
based cables.
5. Copper Based Cables
• Traditional cables consist of copper conductors.
• The invention of the telephone in 1876 created further
demand for copper wire as an electrical conductor.
• Despite competition from other materials, copper
remains the preferred electrical conductor in nearly
all categories of electrical wiring.
6. Properties of Copper Conductors
• Electrical conductivity
– Copper has the highest electrical conductivity rating of
all non-precious metals.
• Tensile strength
– Copper can be bent, twisted, and pulled without
stretching or breaking.
Contd..
7. • Corrosion resistance
– Copper resists corrosion from moisture, humidity,
industrial pollution, and other atmospheric influences.
• Ease of installation
– It can be bent or twisted easily without breaking.
– It can be stripped and terminated during installation or
service with far less danger of nicks or breaks.
8. Processes for Copper Cable
Manufacturing
• Drawing of single copper conductor rolls from raw
copper wire and single steel conductor rolls from raw
steel wire .
• Annealing treatment of copper conductor rolls.
• Tinning treatment on steel conductors and annealed
copper conductors.
• QA testing of conductor rolls.
Contd…
9. • Stranding of copper and steel conductors depending
on the configuration of the cable.
• Insulation of the stranded conductors depending on
the configuration and use of the cable.
• QA testing of the final cable roll before dispatching.
10. Cables Manufactured at OCF
• Carrier Quad Cable.
• Field Telephone Cable.
• Twenty Conductor Cable.
11. Carrier Quad Cable
Temp. Range -55°C to 90°C
CR 24.5 Ohms/Km
Pair Capacitance 50p F/m
Impedence 144 Ohms at 10 Khz & above.
125 Ohms at 60 Khz & above.
120 Ohms at 100 Khz & above.
Attenuation 0.9 dB/Km at 1.6 KHz
1.8 dB/Km at 16 KHz
3.2 dB/Km at 100 KHz
CQC Cables are used to provide carrier trunk connections.
12. Field Telephone Cable
Temp. Range -40°C to 80°C
CR: 76 Ohms/Km
Pair Capacitance 37p F/m
Impedence
600 Ohms
Attenuation
1.4 dB/Km at 1.6 KHz
Breaking Load
76 Kgs
13. Twenty Conductor Cable
Temp. Range -40°C to 80°C
CR. 85 Ohms/Km
Pair Capacitance 40p F/m
Impedence
600 Ohms At 1.6 KHz
Attenuation
2.0 dB/Km at 1.6 KHz
Breaking Load
300 Kgs
14. Optical Fibers: Manufacturing and
Cabling
• Optical Fibers are thins long strands of ultra pure glass
(silica) or plastic(polymers) that can to transmit light from
one end to another without much attenuation or loss.
• Optical fibers are widely used in fiber-optic
communications.
• The light source at the transmitting end is modulated by
the electrical signal and this modulated light energy is fed
into the Optical Fiber.
Contd...
15. • The optical fiber elements are typically individually coated
with plastic layers and contained in a protective tube
suitable for the environment where the cable will be
deployed.
• It has following layers
– Core- Made of highly pure glass with refractive index for the
light to travel.
– Cladding- A middle layer of glass with a lower refractive index.
– An outer polymer jacket to protect the fiber for damage.
16.
17. Why Optical Fibers?
• Cost effectiveness & stable over long distances.
• Available in different sizes, refractive index, index
profiles, material and operating wavelength for
different systems applications.
• It can be handled in a more efficient manner than
conventional electrical transmission cables.
18. Optical Fibers Copper Cables
Extremely low loss (0.3db/km) Very high losses (30db/km)
High bandwidth (7000 Limited bandwidth
channels)
1/8th weight of copper Heavy for usage
Electromagnetic Interference Affected by Electromagnetic
and Noise Proof Interference
19. Fiber Optic System Devices
• Transmitter (laser diode or LED)
• Fiber Optic Cables.
• Receiver
20. Optical fiber as transmission
medium
• Optical fibers transmit data as light pulses.
• Light propagates by means of total internal reflection.
21. Total Internal Reflection
The angle of the light is always
greater than the critical angle.
Cladding does not absorb any light
from the core.
The extent that the signal degrades
depends upon the purity of the glass
and the wavelength of the
transmitted light.
22. Classification of Optical Fibers
• Optical fibers are classified on the basis of
– Core and cladding materials.
– Refractive index profile.
– Modes of propagation.
23. Core and cladding materials: three
varieties
• Glass core and cladding( SCS: Silica Clad Silica)
– Low attenuation and best propagation characteristics.
– Least rugged: delicate to handle.
• Glass core with plastic cladding(PCS: Plastic Clad
Silica)
– More rugged than glass; attractive to military applications.
– Medium attenuation and propagation characteristics.
24. • Plastic core and cladding
– More flexible and more rugged.
– Easy to install, better withstands stress, less expensive,
weighs 60% less than glass.
– High attenuation: limited to short runs.
25. Refractive index profile: two types
• Step index
– Refractive index makes abrupt changes.
• Graded index
– Refractive index is made to vary as a function of radial
distance from the center of the fiber.
26.
27. Mode of Propagation: two types
• Single Mode Fiber
– Only one signal travels at a time.
• Multimode Fiber
– More than one signal is present.
28. Single Mode(mono-mode) fibers
• Most important for long haul use.
• Small core ( 7-10 µ) forces the light to follow a linear
single path down its length.
• Lasers are the usual sources of light.
• Most expensive and delicate to handle.
• Highest bandwidth and distance rating (more than 100
kms)
29. Multimode Fibers
• Relatively large diameter core (50-100 µ).
• Step index multimode cable has an abrupt change
between core and cladding. It is limited to about 50
Mbps.
• Graded index multimode fiber has a gradual change
between core and cladding. It is limited to 1 Gbps.
30. Two major communication issues
• Attenuation
– Attenuation is signal loss over distance.
– Light pulses lose their energy , flatten out as they travel down
the cable.
• Dispersion
– Dispersion is broadening of light pulses with time.
– It arises due to physical properties of the transmission medium.
31. Dispersion in MM/SM fibers
• Single mode fiber sustains only one mode of
propagation whereas multimode contains many
modes.
• Large radii of multimode fiber makes it easier to
launch tight into fiber.
• Even LED’s can excite multimode whereas for single
mode lasers are required
Contd…
