Fiber Optics Transmission System (fots) In

By Kovid Kaushik Roll-ece 087

acknowledgements • my sincere thanks to Mr.ALOK

RANJAN, DSTE-TELE. I pay special thanks to Mr. Sudheer Chawla, Mr. Krishna Avatar, Ms Anisha Modak, Mrs. Jyotsana Mr. Sumer Singh, Mr Banty Kr Sao, who in spite of their busy schedule have lent their precious time for helping out me to understand various systems used in DMRC .

Need • Delhi has more registered vehicle than the total number of vehicles in Mumbai, Calcutta and Chennai put together. • Delhi has now become the fourth most polluted city in the world, • Need to improve both the quality and availability of mass transport service. • Is possible only if a rail-based mass transit system,

Delhi MRTS Project • a feasibility study for developing such a

multi-modal MRTS system was commissioned by GNCTD (with support from GOI) in 1989 and completed by RITES in 1991. • will cost approximately Rs 4860 crores • 11 km to underground (METRO) corridor along with 44.30 km of elevated / surface (RAIL) • a joint venture company (viz., Delhi Metro

Fiber Optics Transmission System (FOTS) in DMRC FOTS can be termed as the backbone of DMRC telecommunications .Fiber optical cables are on both sides of the track.You can see as yellow The number of fibers is determined in order to comply with redundancy. The fiber is redundant for security and protection. In case of fiber optic failure, communication can take place via spare fiber while the fiber that is down may be fixed.

The main components of the fiber optic transmition 1. Optical fiber cables 2. Synchronous Digital Hierarchy (SDH) 3. Digital Distribution Frame (DDF) 4. Flexible Multiplexer (FMX) 5. Optical Distribution Frame (ODF)

Optical Fiber Cables Fiber cables are used for the transmission of the data from one station to the other station. An optical FIBRE has two concentric layers called the core(n1, refractive index =1.48 to 1.5) and the cladding (n2, refractive index=1.46 to 1.48). The refractive index of core is slightly higher than that of the cladding i.e. n1>n2. This difference between n1 and n2 allows total internal reflection. Light ray enters the FIBRE and strike core cladding surface at and angle greater than the critical angle. This is totally reflected back into the core. As angle of incidence and angle of reflection are equal the reflected light will again be reflected. The light will continue to travel in zigzag manner down the length of the FIBRE.

SYNCHRONIZED DIGITAL HIRARCHY (SDH) In early 60’s the analog communication was taken over by the digital communication. There are number of advantages of digital communication over analog system. With the advent of semi conductor circuits and the increasing demand for the telephone capacity, a new type of transmission method called Pulse Code Modulation (PCM) made an appearance. It allows multiple use of a single line by means of digital time domain multiplexing. The analog telephone signal is sampled at a bandwidth of 300-3400Hz,

• Audio range

=4khz =4000hz • Sampling frequency =2*4000 =8000hz • No of bits / sample =8 ⇒Bit rate =8000hz x 8 bits/sample ⇒ =64 Kbps ⇒ = .Further the bandwidth of speech signals and visible range is limited .with the advancement in the needs of the frequency bands, this bandwidth must be utilized.

•So the frequencies must be multiplexed in order to transmit maximum information through the channel. •The multiplexing is achieved by time division multiplexing (TDM). •In TDM, the time axis divided into slots and more information can be transmitted. For an audio signal the time period of the signal is 0.025ms. •Time period of the sampled signal = 1/ 8000 =125 ms •This implies that between two samples there is gap of 125 ms. Between this time interval of 125 ms, we can multiplex number of signals.

• When 32 channels are multiplexed for a transmission rate of 2.048 Mbps speed also E1

•

E2=4E1

E3=4E2=16E2

STM1= 63E1

Access-MUX •D

PIDS (Passenger Information Display System)

• There are 2 pids panel on each

platform plus 1on each side of concorse . • It gives us direction and countdown ei. 4 means train is 4 stations behind . • Display panel consist of LEDs with matrix display • Panel cards 1 LED card 2

PAS( passenger addressing system) • Pas broadcasting of voice messages • Exchanger net card –takes voice data • SA2(Serial Address) card –decides in which zone should announcement be made . OCC SERVER Zone 8M Shaper Gatekeeper Amplifier Speaker

EBTS (Enhanced base transceiver system) • Remote site functionality • Redundancy for fots (@128kbps) • DMRC uses motorola dimetra having benefit of TETRA standards range is 380-400MHz. • Line Of Site usage 15 EBTS sites 25 to 75 miles apart

Breaker panel functions for power distributions Overload protection circuit breakers provides Manual on/off plus auto. Junction panel cabinet grounding ,inter-cabling Cable terminations Cavity Combiner It combines TX and RX signals Sends them to APM Receiver Multi Coupler provides serial ports via receiver in BR and combines them in TDM Environment Alarm system Analog power monitor measures incident and reflected power via vswr ranges from zero to infinity . Filter tray contains band pass filter

Tetra site Controller site controller provides the X.21 interface to master site and BR operations Can control 7BRs folowing are the components of TCS 1 Power PC mother board Site reference ISA card this uses GPS signal to provide time or frequency reference . X.21 interface card Ethernet LAN PCI card Flash memory card Base Radio has 4channels

CLOCK SYSTEM

• Global Positioning System (GPS) by Master Clock at OCC. • gps>> srs>>master clock >>Lan>>submasterclock PL2QA TB

LNA PL GPS

TC TB

PL TC

EPABX (Electronics Private Automatic Branch Exchange) • self-sustained telephone exchange • EPABX System at OCC: • Telephone system shall interface to the radio

system to enable radio users to initiate and receive calls to/ from EPABX extension or to MTNL or TATA INDICOM telephones. • Centralized Digital Recording System: The telephone system is equipped with a CDRS for recording of designed lines, emergency PAS announcements and designated conversion system. • Network Management System: The telephone

Shelf 0 &Shelf 1 2 Power cards: This card distributes power to wholerack SF2X8 card: This card provides LAN ports for monitoring of EPABX at other stations. • 2 DXCXL cards: These are CPU cards used for networking purposes. • ADP: Administrative Data Processor. This is also a CPU card performs controlling information. • HDMO card: Hard Disk Magneto Optical card used for all software information backup.

Shelf 1

• 2 SLMAC cards: This card is for analog

phones. Maximum 24 phones can be connected to each card. • 2 SLM02 cards: This card supports digital phones. Maximum 24 phones can be connected to each card • LTUCA card: This card connects shelf 1 and 0 in EPABX rack. • 2 DIUN2 cards: This card takes E1 signal from DDF. Links one station to other stations. There are 2 ports in each card, one for analog and another for

Station 2

Station 1 EP A BX

D DF

SD H

Station 2 OD F

OD F

SD H

DDF-Digital Distribution Frame SDH-Synchronous Digital Hierarchy ODF-Optical distribution Frame

D DF

EP A BX

conclusion • Through this presentation I would

conclude that in dmrc all the systems are interdependent synchronization is as important • Dmrc has compiled all the new technology to make efficient company .

Thank You