3INDEX 1. COMPANY PROFILE 2. INTRODUCTION 3. ABOUT THE EXCHANGE 4. MDF >TYPES OF FAULTS>PROTECTIVE DEVICES5. OCB6. GSM7. MEDIA8. PROCEDURE FOR HANDLING COMPLAINTS
4INTRODUCTIONToday, BSNL is the No. 1 telecommunication company and the largest public sector undertaking of India and its responsibilities includes improvement of the already impeccable quality of telecom services, expansion of telecom services in all villages and instilling confidence among its customers.EXCHANGE:Equipment which effects interconnected of telephones is known as switching equipment.The switching centre, which houses the terminating and switching equipment is called telephone exchange.
5EXCHANGE LAYOUT Typical exchange consist of : Switch RoomOperations and Maintenance (OMC) RoomInput Output processor (IOP) RoomPower Plant RoomBattery RoomMain Distribution Frame (MDF) Room
6ABOUT THE EXCHANGE1. All telephone subscribers are served by automatic exchanges.2. Today’s automatic exchanges uses a pair of computers.One, running the program that provides services.Second, monitoring the operation of the first, ready to take over in a few seconds in the event of equipment failure. Various exchanges present in BSNL are: > C-DOT > OCB > EWSD
7MAIN SECTIONS OF EXCHANGE: There are three components of exchange:MDFPower plantSwitching Room.
8Main Distribution Frame (M.D.F) : INTRODUCTION: - MDF means Main Distribution Frame. Local cable contact at MDF .- All types of cables out to the door contact connection at MDF .
9POWER PLANT :The main parts of the power room are: 1. Batteries 2. UPS (Uninterrupted Power Supply) 3. Charging - Discharging Unit Inverter and Converter Unit:
10SWITCHING ROOM :Switch room consists of BM and CM cabinets mounted in standard switch.These cabinets are fastened to a switch Room and interconnected by cables.
11MAIN DISTRIBUTION FRAME .MAIN DISTRIBUTION FRAME> The primary function of MDF is to remove fault. It is also known as Fault Remove Section.> The telephone numbers are also disconnected in the MDF because of some specific reason.ORGANISATION OF THE MDFVertical sideHorizontal side
12VERTICAL SIDE RACK: -On the rack, the tags are situated. One rack is having eight tags. The counting is done from up (0) to down (7). TAGS: -Each rack consists of eight tags. 1 tag = 4 core 1 core = 4 bunch 1 bunch = 2 line N.E.:-The word NE stands for the ‘NUMBER OF EQUIPMENT’.It is used for testing number andWEDGE: Wedge is used as a device for checking the ring. Wedge is placed in jack strips, which is connected to telephone for checking.
13HORIZONTAL SIDE:The horizontal side connected to the underground cable.This cable is having 100 pairs. These pair is distributed when we allot the telephone number to the subscriber.Horizontal side is again subdivided in two parts:One part is connected with the vertical side.Another with the subscriber line by using 100 pair underground cable.
14CONSTRUCTION OF M.D.F:-Main distribution frame is mainly divided in two parts.(1) Vertical Side or Line side.(2) LEN side or Exchange side.
15VERTICAL SIDE:All the part from vertical side to the subscriber are generally called outdoor section.:1. One vertical has 10 tag blocks.2. Each tag block has 10 rows and each row has 10 tags. So each tag block has 100 tags.3. Connection between vertical side & subscribers are provided by jelly filled cables.4. These wires are first terminated in cabinet box, then according to requirements the group of the wires (e.g. 200 wires, 100 wires etc.) is terminated in pillar box
16LEN SIDE: • All the parts from LEN to the exchange is called indoor section. • The connection of subscriber from exchange is terminated on this side of MDF.• In 1 tag block there are 128 tags. Each tag block is divided in 4 segments. That is 0, 1,2 & 3 and in each segments.
17. DIFFERENT TYPES OF FAULTS:- LOOP FAULT:-If two wires are joined together because of improper connection, storming air etc. EARTH FAULT:-If two wires get scrape at some places and if this wire comes in contact with tree, pillar or any metal objects then this type of fault occurs. CABLE FAULT:-For outdoor connections, jelly filled wires are used which are affected by natural causes such as rain, earthquake etc. At such time this fault occurs. DISCONNECT FAULT:-This type of fault occurs due to the breaking of wires between the vertical side & LEN side.
18Gas Discharge Tube(G.D Tube) Insertion Tool Wires PROTECTIVE DEVICES USED IN M.D.F.FusesGas Discharge Tube(G.D Tube)Insertion ToolWires
19OCBThe new switching systems are based on Stored Program Control concept. The call processing programmers are distributed over different control organs of the system and are stored in ROM/RAM of the units Processor in the control units .Features:It is a digital switching system.The system supports all the existing signaling system .The system has ‘auto recovery’ feature. When a serious fault occur in control unit, it gives a message to SMM (operation & maintenance unit).
20GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM) Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standardGSM is a cellular network which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM operates in the 900 MHz frequency band.
21There are five different cell sizes in a GSM network- Macro CellsMicro CellsPico CellsFemto CellsUmbrella Cells
22GSM : (SYSTEM ARCHITECHTURE) This system structured hierarchically as shown:It consist of one administrative region, which is assigned to a MSC(Mobile Switching Center).Each administrative Region is made up of atleast one Location Area(LA). LA is also called the visited area.An LA consists of several cell groups.Each cell group is assigned to a base station controller(BSC).Cells of one BSC may belong to different LA’s.
24BASIC BUILDING BLOCKS: Mobile Station (MS)Base Station (BS)Mobile services Switching Center (MSC)DatabasesOperation and Maintenance Center (OMC)
25SYSTEM CAPACITYShannon’s Theory predicts the maximum amount of information that can be transmitted over a channel with given BW & SNR.The optimum usage of given BW is obtained when the signal are noise – like & min SNR.Hence for increased capacity the choice is CDMA.