49700940-switching
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SWITCHING
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What is switching?
How is switching is made?
Switching is setting up a temporary connection b\w
2 or more exchange termination.
Exchange provide a temporary path for simultaneous,bi-directional transmission of speech
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EXCHANGE
STORED PROGRAM
CONTROLLED EXCHANGE
ELECTROMECHANICAL
EXCHANGE
Relays and switches are used for
providing a closed path b\w two
subscriber for the data, voiceexchangement
Modification impossible
Subscribers cant modify their owndata entries for supplementary
services, such as on-demand call
transfer, dialing, short code etc.
Routine test required to check faults
These exchanges works according to
the data store in the processor
Modification become possible by
changing the data stored in
processor
Can provide modification service to
subscriber
Automatically faults are detected
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BLOCK SCHEMATIC OF SPC EXCHANGE
TERMINAL EQUIPMENT
SWITCHING NETWORK
SWITCHING PROCESSOR SWITCHING PERIPHERALS
SIGNALING INTERFACES
DATA PROCESSING PERIPHERALS
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In this equipment, line , trunk, and service
circuit are terminated for the detection,
signaling, speech, transmission, and
supervision of calls.
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Largest sub-system in terms of size of the
equipment. Its main function :
Switching
Transmission
Types of electronic switching system
o Space divisiono Time division
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Continuous physical path is set up betweeninput and output terminations.
Path is separate for each connection and is
held for entire duration of the call.
Same path is used by number of call.
The path is sequentially shared by number of
call for a fraction of time {time=125s}7
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Network
Special purpose real time computer, designedand optimised for dedicated application ofprocessing telephone calls
Block schematic of a switching processor
Central control processor
Programme Store
Data store
Translation Store
To SwitchingTo Switching
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There are speed buffer and interface b\w processorand component in telephone switching section asboth operates at different speed.
Scanner
Marker
Distributor
Bus system
Line interface circuits Analogue subscriber line interface
Transmission interface
Signaling interface9
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Type of signaling
CAS ( Common associated signaling )
CCS ( Common channel signaling )
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Electronic exchanges work on the principle of
Stored Program Control. All the call processing
functions are performed on the basis of pre-
designed programme which is stored on the
memory of the central processor.
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C_DOT DSS MAX :Universal digital switch { perform local, transit, or
integrated local and transit switch role }
BASIC GROWTH/BULIDING MODULESBASE MODULE
CENTRAL MODULE
ADMINISTRATION MODULE
INPUT OUTPUT MODULE
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The Base Module (BM)
The basic growth unit of the system.
It interfaces the external world to the switch.
The interfaces may be subscriber lines,analogue and digital trunks.
Each Base Module can interface upto 2024
terminations.
It carries out majority of call processing
functions
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The Single Base Module (SBM)
In Single Base Module (SBM) exchange
configuration, the Base Module acts as anindependent switching system and providesconnections to 1500 lines and 128 trunks.
In such a configuration, the Base Module directlyinterfaces with the Input Output Module .
It is a very useful application for small urban andrural environments.
With minimum modifications in hardware a BaseModule(BM) can be remotely located as aRemote Switch Unit (RSU), parented to the mainexchange using PCM links.
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Central Module (CM)
It consists of a message switch and a spaceswitch to provide inter-modulecommunication
It perform voice and data switching betweenBase Modules.
It communicates with Administrative Module
for operation and maintenance functions. It also provides clock and synchronisation on a
centralised basis.
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Administrative Module
It support administration and maintenancefunctions
It communicates with the Base Module via the
Central Module. It supports the Input Output Module for
providing man- machine interface.
It also supports the Alarm Display Panel forthe audio-visual indication of faults in thesystem.
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Input Output Module (IOM)
It is a powerful duplex computer system
It interfaces various secondary storage devices
like disk drives, cartridge tape drive and floppy
drive.
It supports printers and ports for video
display units which are used for man- machine
communication interface.
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REMOTE SWITCH UNIT The normal BM can be modified for remoting
with the host exchange via 2 Mbps digital links. The number of 2 Mbps links between the Main
Exchange and RSU is primarily determined by the
traffic.
Operation and maintenance functions are
handled by the host exchange.
A maximum 16 RSUs are possible in C-DOT DSSMAX-XL and 8 RSUs in MAX-L.
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