PPT on signalling and optical fiber and the topic which are related to RDSO

1. Industrial training presentation
Research Designs and
Standards Organization (RDSO)
(Telecom Directorate)

2.  INTRODUCTION
 ABOUT RDSO
 SIGNALING IN INDIAN RAILWAYS
 SOME IMPORTANT TERM IN RAILWAYS
SIGNALING
 OPTICAL FIBER
 STRUCTURE OF OPTICAL FIBER
 WORKING PRINCIPLE AND USES OF
OPTICAL FIBER
 OPTICAL FIBER SLICING
CONTENT

3. INTRODUCTION

4. ABOUT RDSO…….
Research Design and
Standard
Organization (RDSO)
was formed in 1957,
under Ministry of
Railways at Lucknow
All the directorates of
RDSO except Defence
Research are located
at Lucknow

5. ABOUT RDSO…….
RDSO is the sole R&D organization
of Indian Railways and functions as
the technical advisor to Railway
Board Zonal Railways and
Production Units and performs the
following important functions:
 Development of new and
improved designs.
 Development, adoption,
absorption of new technology for
use on Indian Railways.
 Development of standards for
materials and products specially
needed by Indian Railways.
and many more…

6. Signaling in Indian Railways
 Railway signaling is a system used to
control railway traffic safely,
essentially to
prevent trains from colliding.
 There are basically two purposes
achieved by railway signaling:-
 To safety receive and dispatch
trains at a station.
 To control the movements of trains
from one station to another after
ensuring that the track on which
this train will move to reach the
next station is free from movement
of another train either in the same
or opposite direction.
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7. Some Important terms in Railway Signaling
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• To run the train system according to a timetable.
• Trains may only run on each section of track at their
scheduled time.
Timetable
operation
• One train is permitted in each block at a time.
• Can be manually or automatic controlled.Block signaling
• To determine whether a section of line is occupied is by
use of a track circuit.Train detection
• To indicate to drivers whether the line ahead is
occupied.
• To ensure that sufficient space exists between trains to
allow them to stop.
Fixed signals
• Displaying the same aspects by night as by day.
• Require less maintenance than mechanical signals.
Color light
signals
• To inform a driver which route the train will take beyond each
signal.
• To drive the train at the correct speed for the route to be taken.
Route and speed
signaling

8. Optical fiber
 An optical fiber is a hair thin cylindrical of
glass or any transparent dielectric.
 The fiber which are used for optical
communication are wave guides made of
transparent dielectrics.
 Its function is to guide visible and infrared
light over long distances.

9. 9

10. Structure of optical fiber

11.  Core – Central tube of very thin size made up of
optically transparent dielectric medium and carries the
light form transmitter to receiver. The core diameter
can vary from about 5um to 100 um.
 Cladding – outer optical material surrounding the
core having reflecting index lower than core. It helps
to keep the light within the core throughout the
phenomena of total internal reflection.
 Buffer Coating – Plastic coating that protects the
fiber made of silicon rubber. The typical diameter of
fiber after coating is 250-300 um.

12. Working principle
Total Internal Reflection
 When a ray of light travels from a denser to a
rarer medium such that the angle of incidence
is greater than the critical angle, the ray
reflects back into the same medium this
phenomena is called total internal reflection.
 In the optical fiber the rays undergo repeated
total number of reflections until it emerges out
of the other end of the fiber, even if the fiber is
bent.

13. Total internal reflection in optical fiber

14. Uses of Optical Fiber
 Fiber optic can accommodate variety of
needs.
 It can be used in Communication, fiber
optic sensors, illumination, medical.
 And also in other places where bright light
needs to be shone on a target without a
clear line-of-sight path.
 Used in building to route sunlight from the
roof to other parts of the building.
 And many more usages but we will only
discuss use of optical fiber in
communication here.
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15. In Communication
 Optical fiber can be used as a medium for
telecommunication and computer
networking because it is flexible and can be
bundled as cables.
 It is especially advantageous for long-distance
communications, because light propagates
through the fiber with little attenuation compared to
electrical cables.
 The per-channel light signals propagating in the
fiber have been modulated at rates as high as
111 gigabits per second (Gbit/s) by NTT, although
10 or 40 Gbit/s is typical.
 In June 2013, researchers demonstrated
transmission of 400 Gbit/s over a single channel.
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16. OPTICAL FIBER SPLICES -
FUSION
Fusion splices are
expensive, fully automated
machines that do most of
the work. The operator uses
a high quality clever to
prepare the fibers and
inserts them into the jaws
of the splicer. The machine
automatically aligns the
ends, makes the splice and
even gives an estimate of
the loss. The operator then
places the splice in a holder
which also seals it and
inserts it in a splice tray.

17. OPTICAL FIBER SPLICES - FUSION
While fusion
splices are
expensive($5000+)
, but each splice is
cheap. So if you
are doing lots of
splices, fusion is
more cost
effective.

18. Thank you