telecommunacation in`DMRC

transcript

Summer Internship With

DELHI METRO RAIL CORPORATION.LTD. (A joint Venture of Government of India & -Government of Delhi)

Name:RISHIKANT SINGH Enrollment No:10ESMEC070

The basic components of

telecommunication department can be

stated as follows:

FOTS ( Fiber Optic Transmission System)

PIDS (Public Information Display System)

PAS (Public Address System)

Master Clock

CCTV (Closed Circuit Television)

Radio System

EPABX (Electronic Private Automatic Branch Exchange)

Operational Control Center (OCC)

Located at Shastri Park and Barakhamba.

It controls both Rail & Metro Corridor.

Here all the central systems of various systems

are located.

All the train movements are supervised and

system monitoring equipments are installed in

OCC Theatre

CHIEF CONTROLLER AT OCC

VIEW OF OCC FROM TOP

EQUIPMENT ROOM IN OCC

It is used to display traffic &

train scheduling information

also data related to arrival &

departure time and other

information along the station and various platform

areas .

Public Information Display System(PIDS):

• It is used to broadcast voice messages to

passengers/staff

in all stations , depots ,OCC and DMRC Headquarter.

•Also used for emergency evacuation broadcast .

Public address system(PAS):

Clock system is used to provide accurate time to

staff, passengers and time reference to systems

at DMRC. Accurate and synchronized time

information is obtained from Global Positioning

System (GPS) by Master Clock at OCC.

Master Clock system:

•This is used to monitor the station and the platforms

along with the metro corridors where it is very difficult

to keep a view on the corridors.

•Mostly it is used for security reasons and help train

operators in the curved station platforms.

Closed Circuit Television System(CCTV):

For purpose of planting communication link

between different stations, DMRC has its self-

sustained telephone exchange. This system

works on -48 V DC. Data is processed at a rate of

64k bps.

Electronic Private Automatic Branch Exchange (EPABX) :

Radio Waves

A radio uses electromagnetic waves to send

information across the air. This is accomplished by

producing an electrical signal that moves back and

forth, or oscillates, at a rapid rate.

Frequency Spectrum

• Terrestrial Trunked Radio (TETRA) (formerly known as Trans European Trunked Radio) is a specialist professional Mobile Radio and two-way transceiver specification.

• This standard was developed by the ETSI for private mobile radio. Open standard for private mobile radio. It defines radio services and interfaces

• The TETRA standard defines the air interface between mobile stations and the infrastructure.

Technology in use:

Radio system in DMRCThe Radio system is a digital trunked radio system,

operating in 380-400 MHz band and confirming to

TETRA standards.

The Radio system have central control equipment

installed in OCC.

The Radio system uses EBTS towers for communication

in rail corridor & leaky coaxial cable along each track in

the tunnels for communication with train borne mobile

radio (in metro corridor) .

RADIO CENTRAL EQUIPMENT AT OCC

The trunking concept allows channels or other

resources to be made available to users as

they are needed. It allows all the channels to

be pooled together. As a channel is needed,

the controller grants an available channel

from its pool of channels.

Trunking

TETRA Trunking

SC=Site ControllerCC=Control ChannelBR= Base Radio

Talk group

In most organizations, radio users work in groups

that are based on their functions and

responsibilities. These groups of radio users can be

assigned to communication talkgroups that reflect

their function or responsibilities.

Calls are semi-duplex.

TYPES OF MODES OF COMMUNICATION:

1. Trunk Mode Operation:

It represents communication

between two or more TETRA

mobile stations with the use of

trunking network infrastructure.

This mode consists of 4 communication modes:

(a)Group mode (b) Private mode

(c) Phone mode (d) Emergency mode

It is a half duplex communication

mode in which many users

can communicate with each

other by selecting a

common talk group.

(a) Group Mode:

(b) Private Mode:

It is a half as well as full duplex

communication mode in which many users

can communicate with each other

privately without interfering the talk group.

It uses two frequencies.

(c) Phone Mode:

It is a full duplex mode of

communication in which a radio

user can talk to any dialed

phone number within DMRC or

external network connected to DMRC.

(d) Emergency Call:

The emergency key is provided on

every radio equipment, an audio

visual alarm will appear on every radio unit in that

group. The party who initiates the call has

the highest priority for calling.

2. Direct Mode Operation:

• It represents direct communication between two or

TETRA mobile stations without the use of trunking

network infrastructure.

• Simplex mode of communication.

EBTS (Enhanced base Transreceiver

System )

• It provides RF interface from the master

site to the mobile subscribers in a TETRA

system. It can be categorized in two

configuration:

(a) Above ground (Rail corridor)

(b) Under ground (Metro corridor)

•Both are of same configuration & characterstics.

Call Through EBTS

Central Secretariat

Vishwa Vidyalaya

ISBTShahdara

Khyber Pass Depot

Shastri Park Depot

Shastri Park Station

Patel Chowk

Connaught Place

New Delhi

Chawri Bazar

Delhi Main

Old Secretariat

Civil Lines

Gautampur

Seelampur

Metro Corridor(underground)

Rail Corridor(at-grade or elevated)

Radio Base Station Site

Central Secretariat

Vishwa Vidyalaya

ISBTShahdara

NorthNorth

Khyber Pass Depot

Shastri Park Depot

Shastri Park Station

Patel Chowk

Connaught Place

New Delhi

Chawri Bazar

Delhi Main

Old Secretariat

Civil Lines

Gautampur

Seelampur

TransmitterA transmitter transmit radio signal

A transmitter usually has a power supply, an

oscillator, a modulator, and amplifiers

Receiver

A receiver is a device that receives a radio

signal from an antenna and decodes the signal for

Generally, receiver refers to a demodulator, a

preamplifier, and a power amplifier

Types of radio used in DMRC:

1. Mobile Vehicle radio\Fixed

(a) RAU (Radio Access Unit) or Zetron radio set or

Station radio

(b) Train radio set

(c) RCW (Radio console workstation)

2. Mobile Portable radio

Each radio has its radio identification which

register itself in central system for its function.

The radio is programmed for its ID, frequency,

network code, talk group and allowing types of

call. Radio consists of trans and receiver and

frequency synthesizer circuit which function along

with DSP (Digital Signal Processor) for digital

function.

RAU(Radio Access Unit) It is located in the Station control room.It is placed in the best radio coverage and it is fixed & has a functionality just like a telephone radio.It is ideally suited to radio operator dispatchers and where office personnel need access to a radio system without wanting to have a radio placed into the office environment.The M390 is a robust telephone style desktop controller with a large ,easy to read LCD display & handset.

Block diagram of Zetron Setup

Train radio

MTM700 Mobile radio is installed at front & rear cab for communication between the train driver & designated station controllers at OCC & Depots.

This radio unit is connected to different units e.g. TRIU,TRCP; these units are required to communicate with RCW ,TIMS, ATS and rear cab radio.

Dome type omni directional antenna is located at top roof of train. This antenna is connected through RF cable which is connected to radio unit.

Front and rear view of Train radio in cab

Radio console workstation

• It is for different controllers that is working in OCC such that chief and traffic controllers ,etc.

• On its MMI ,all the radio information is displayed and communication can be set up only by clicking the radio identity.

Hand Portable radioThe hand portables come with 3x4 keypads, rotary switch dial, and LCD for number dialing and maximum flexibility. Each hand portable is equipped with an ultra high capacity batteries (Li ion or Li Mgh.) for longest standby and talk-time of 24 hrs, that is 5% transmit, 5% Receive and 90% standby.

Hand portable is suitable for all kinds of calls used in DMRC.

1. The frequency used gives longer range, which permits high levels of geographic coverage with a smaller number of transmitters, thus cutting infrastructure costs.

2.Unlike the cellular technologies, TETRA is built to do one-to-one, one-to-many and many-to-many.

3. Rapid deployment (transportable) network solutions are available for disaster relief and temporary capacity provision.

4. In the absence of a network mobiles/portables can use 'direct mode' whereby they share channels directly (walkie-talkie mode).

Advantages of TETRA:

1. Requires a linear amplifier to meet the stringent RF specifications that allow it to exist alongside other radio services.

2. Handsets are more expensive than cellular.

3. Handsets can sometimes interfere with badly designed (usually old) or sensitive electronic devices such as broadcast (TV) receivers, hospital equipment, speed cameras.

Disadvantages of TETRA:

Conclusion:TETRA communication system has been

implemented successfully

The signals are clear

The voice clarity is excellent

The TETRA technology effectively meets DMRC’s operational and functional expectations

Conclusion:In my training I have got to know about the different

means of communication systems used in DMRC. It consists of radio communication techniques & radio systems; and data transfer between stations and the OCC.

My presentation focuses on radio system. My conclusion from this training is that DMRC uses two types of radio systems:

a)Fixed Radio(Zetron, train radio, RCW)b)Portable Radio(Tetra)Both have their advantages and disadvantages. Fixed

radio equipments provide better voice clarity, but can not be moved when placed at a particular place. Similarly Portable radio equipment can be moved from place to place, but voice clarity may vary as device might not provide 100% signal at all places.

telecommunacation in`DMRC

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