OCB 283 EXCHANGE ORGAN CONTROL BASE VERSION 283 A Modification of ALCATELALCATEL-E10 -E10 First OCB exchange exchange of RR-11 -11 version was commissioned in France First OCB exchange came to India in 1993 Has been upgraded to RR-20 -20 & R R--25 -25 It can work at temp. 55 -25 -25° 25°C °C though the optimum temperature is 22 22°°C °C
SALIENT FEATURES OF OCB 283 It is a digital switching system A maximum of 2048 PCM switches can be conducted Supports both digital and analog subscribers Various units of the system are connected over token over token ring which enables fast exchange of information All the control units are implemented on same type of hardware.. This is called a station. hardware The system has a modular architecture and the expansion can be very easily carried out by adding necessary hardware and software
ARCHITECTURE OF OCB The OCB exchange consists of three blocks: 1. Connecting units 2. switching network 3. control units DGITAL LINKS
CONECTN UNITS
SWITCHING NETWORK
DIGITAL LINKS
CONTROL
UNITS
STATIONS IN AN OCB 283 Hardware unit consisting of a number of processors and couplers connected to a common bus BSM (multiprocessor (multipro cessor station bus) various stations in OCB 283: SMC SMA SMT SMM STS These stations communicate among themselves on a token ring called MIS (Inter Station Multiplex)
SMC-- Ma SMC Main in Control Contr Con trol ol Station Stati Sta tion on Various
control functions are: Multi--Register(M Multi egister(MR) R):: there are 2 to 6 MR and each has 256 registers of 32 bit each. When a number is dialled it stores the number of the calling party Tr anslator (TR) (TR):: keeps a record of the exchange facalities and it decides whether a subscriber can use a facality f acality or not Marker (MQ) (MQ): These are two in number and it activates the other parts of the switch Charging unit (TX) (TX):: There are 2 TXs in OCB 283, both are synchronized so that no data is lost. Time is noted in it and it gets updated after sometime. Matrix Sy System stem Handler (GX) (GX):: It processes & makes connection in switching matrix on the order from MR or MQ. Common Channel signaling Network Controller: Manage the CCS#7 network for signaling.
SMA- Auxiliary Auxiliary Multiprocessor Multiprocessor Station Functions unctions:: 1. Tone Generation (GT) 2. Conference Call (CCF) 3. Frequency Generation & Reception Receptio n (RGF) SMT (Trunk Multiprocessor S Multiprocessor Station tion)) Functions: it acts as an interface between the junctions of other exchange & the PCB chips of OCB exchange STS (Sy Sync nch hronization & Time Base Station tion)) Functions: 1. It is the clock system of OCB 2. the clock needs to be synchronized with the network it has two partss: 1. synchronization part 2. time base generator part BTT (Base Time Triplicate te)): driven by the synchronizer and it distributes the clock to the switch.
SMM (Maintenance Multiprocessor S Multiprocessor Station tion)) SMM station in ocbocb-283 -283 performs the Operation & Maintenance functions. OCB--283 OCB -283 has Auto Auto Recovery feature feature.. When a serious fault occurs in a Control Unit, it gives a message to SMM (Operation & Maintenance Unit) which puts this unit out of service, loads the software of faulty unit in a backup unit and brings it into service. Diagnostic programmes programmes are run on the faulty system and diagnostics are printed on the terminal. Main functions: 1. operation & maintenance function implementation 2. central defence of OCB
STRUCTURE OF THE EXCHANGE OMC ROOM
ETM (Translator and Interpreter
Switch Room
Exploitation Room
M.D.F. (Main Distribution Frame)
OMC Roomoom- (Operation & Maintenance Room) in OMC Room there are: Hard Disk & Tape Drives : meter reading and subscriber details The Interpreter or the translator which converts the Source Code into the Binary Code which the Electronic Circuits deal in. ETM:
The hard disk of the OCB is 200 GB Switc witch h room has all the Electronic Circuits & the Temperature control of the switch room is a must as the Processor gets heated and may lead to improper functioning.
MAIN DISTRIBUTION FRAME In telecommunications, a distribution f rame rame is a passive device which terminates cables, allowing arbitrary interconnections to be made. MDF terminates the cables leading to subscribers on the one hand, and cables leading to active equipment in the exchange Each external connection shares a copper connector that connects one punch location on the front of the MDF to a single s ingle punch location on the back of the MDF. These patching points as 'punc punch hes¶
EXPLOITATION ROO ROOM M This is the Room from where all the changes are made. In this room we have Teletypewriters (TTY) on which we receive all the alarms Teletypewriters consist of: VDU (Visual Display Unit) Keyboard CPU (Central Processing Unit) We make the modifications from these TTYs T TYs To the teletypewriters printers are attached and all the commands that executed are printed side by side.
CONNECTING SYSTEM
Exchange
MDF
Exchange Side
Subscriber
Cabinets
Line Side
Distribution Poles
Pillars
Cables from the Exchange reach the MDF From the MDF Underground Jumper Cables go to the Cabinets The Capacity of the Cabinets is around 2000 pairs of twisted cables If the number of subscribers is small then there is no need for the Cabinets From the Cabinets the cables go to the Pillars From the Pillars the wires go to the DP DPs s The position of the pillars is chosen c hosen such that the length of the wires going to the DP DPs s is equal in all directions. The capacity of each of the Pillars is about 10 or 15 From the DP DPs s the wires go to the subscribers¶ homes
FAULT CHECKING When a fault is reported then first check is made at the MDF, a Phone set is inserted on the Line Side, some number is dialed and it is checked if the conversation takes place properly If the conversation takes place properly then the fault is said to be on the Line Side (Outdoors) But if there is no Dial Tone T one then the fault is said to be on the Exchange side (Indoors) If there is dial tone at the Pillar r but but not in the subscribers home then the fault is in between the DP and the subscribers phone set. Otherwise at the Pillar If there is dial tone at the Pillar r but but not at the DP then the fault is in between the DP and the Pillar Otherwise the phone is checked at the Cabinet If there is dial tone at the Cabinet but not at the Pillar r then then the fault is in between the Cabinet and the Pillar Otherwise the only option left is that the fault is in between the MDF and the Cabinet.
PULSE CODED MODULATION Two types of PCM: Frequency Division Multiplexing: It involves sharing of Frequency slots within the bandwidth of the transmission medium. Time Division Multiplexing: it involves sharing of the channel during different time slots
STEPS IN PCM SAMPLING QUANTIZATION COMPANDING ENCODING DECODING
