telecommunacation in`DMRC
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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.
OCC Theatre
CHIEF CONTROLLER AT OCC
VIEW OF OCC FROM TOP
EQUIPMENT ROOM IN OCC
Line1
Line2
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
talk
group. The party who initiates the call has
the highest priority for calling.
2. Direct Mode Operation:
• It represents direct communication between two or
more
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
R1R2
M1
M2
Central Secretariat
Vishwa Vidyalaya
ISBTShahdara
North
R3
DCC
Khyber Pass Depot
DCC
Shastri Park Depot
Shastri Park Station
OCC
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
Radio Base Station Site
R1R2
M1
M2
Central Secretariat
Vishwa Vidyalaya
ISBTShahdara
NorthNorth
R3
DCC
Khyber Pass Depot
DCC
Shastri Park Depot
Shastri Park Station
OCC
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
Radio Base Station Site
Metro Corridor(underground)
Rail Corridor(at-grade or elevated)
Radio Base Station Site
Radio Base Station Site
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
use
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.