usefull presentation

1. NAME : S.PRIYADHARSINI
YEAR : III YEAR
SECTION : ECE –A
REG NO : 1090110103283
GAGET : OTDR
DATE : 07-10-2011

2. OTDR
Optical Time-Domain Reflectometer
 Image from exfo.com

3. WHAT ARE OPTICAL FIBERS ?
Optical Fibers are thins long (km) strands of ultra pure glass
(silica) or plastic that can to transmit light from one end to
another without much attenuation or loss.
The glass used to make Optical Fibers is so pure that if the
Pacific Ocean was filled with this glass then we would be able
to see the ocean bottom form the surface….!!!!
This is to be believed as repeater distances on long haul routes
for optical fibers vary from 50 to 150 km.

4. BLOCK DIAGRAM

5. Working of Optical fibers?
The light source (LAZER) at
the transmitting (Tx) end is
modulated by the electrical
signal and this modulated light
energy is fed into the Optical
Fiber.
At the receiving end (Rx) this
light energy is made incident
on photo-sensors which
convert this light signal back to
electrical signal.

6. TYPICAL OTDR TRACE

7. Why Optical Fibers ?
As mans need and hunger for communication increased, the amount of
bandwidth required increased exponentially.
Initially we used smoke signals, then horse riders for communicating. But
these ways were way to slow and had very little bandwidth or data caring
capacity.
Then came the telephone and telegraph that used copper wires for
communication. But soon demand out striped the capacity and capability of
copper wires and data transport got added to voice communication. Then
came Coaxial copper cables, VHF and UHF Radios, Satellite but demand still
outstripped the supply.
It was not until Optical Fibers came on the scene that
large amount of communication bandwidth became
economically and easily available to everyone.
As an example 50,000 voice / data circuit copper cable is
massive in size and very expensive, while a single Optical
Fiber, the diameter of human hair, can carry 5,00,000
circuits of voice and data. This capacity is increasing day
by day as supporting electronics is developing. In itself
the capacity of Optical Fibers is limitless.

8. OTDR Uses
 Measure loss
 Locate breaks, splices, and connectors
 Produces graphic display of fiber status
 Can be stored for documentation and later reference
 Cable can be measured from one end

9. VARIOUS TYPES OF OPTICAL FIBER CABLES
1. OPGW Cable
2. ADSS type OF Cable
3. Self-Support AERIAL figure 8 type OF Cable
4. LASHED type OF Cable
5. UNDERGROUND / BURRIED type OF Cables
6. DUCT Type OF Cable

10. ADVANTAGES OF OPTICAL FIBERS
1. VERY HIGH INFORMATION CARRING CAPACITY.
2. LESS ATTENUATION (order of 0.2 db/km)
3. SMALL IN DIAMETER AND SIZE & LIGHT WEIGHT
4. LOW COST AS COMPARED TO COPPER (as glass is made from sand..the
raw material used to make OF is free….)
5. GREATER SAFETY AND IMMUNE TO EMI & RFI, MOISTURE &
COROSSION
6. FLEXIBLE AND EASY TO INSTALL IN TIGHT CONDUICTS
7. ZERO RESALE VALUE (so theft is less)
8. IS DILECTRIC IN NATURE SO CAN BE LAID IN ELECTICALLY
SENSITIVE SURROUNDINGS
9. DIFFICULT TO TAP FIBERS, SO SECURE
10. NO CROSS TALK AND DISTURBANCES

11. DISADVANTAGES OF OPTICAL FIBERS…
1. The terminating equipment is still costly as compared to copper equipment.
2. Of is delicate so has to be handled carefully.
3. Last mile is still not totally fiberised due to costly subscriber premises
equipment.
4. Communication is not totally in optical domain, so repeated electric –
optical – electrical conversion is needed.
5. Optical amplifiers, splitters, MUX-DEMUX are still in development stages.
6. Tapping is not possible. Specialized equipment is needed to tap a fiber.
7. Optical fiber splicing is a specialized technique and needs expertly trained
manpower.
8. The splicing and testing equipments are very expensive as compared to
copper equipments.

12. APPLICATIONS OF OPTICAL FIBERS…
1. LONG DISTANCE COMMUNICATION BACKBONES
2. INTER-EXCHANGE JUNCTIONS
3. VIDEO TRANSMISSION
4. BROADBAND SERVICES
5. COMPUTER DATA COMMUNICATION (LAN, WAN etc..)
6. HIGHT EMI AREAS
7. MILITARY APPLICATION
8. NON-COMMUNICATION APPLICATIONS (sensors etc…)

13. THANK YOU