A Project Report on

2. A Project Report on E 10 B EXCHANGE Presented By: MUHAMMED TAHIR MOHAMMAD IRSHAD MANISH KUMAR SAHU MAHENDRA KUMAR KANWAR TRIPTEE DEWANGAN

3. INTRODUCTION Telephone Exchange is system of electronic components that connects telephone calls. George W. Coy designed and built the first commercial telephone exchange which opened in New Haven, Connecticut in January, 1878. THE E-10 B SYSTEM It is Electronic Digital Exchange Version-B made by France in 1971. First E-10 B exchange was commissioned at Bombay in Feb 1985. A new era of technology in history of Indian Telecommunication. FEATURES No. of Switching PCM links - 384 Processing capacity - 190,000 BHCA Traffic Handling capacity - 4,000 Erlangs System - Time Division Switching, PCM principle used, 2.048 MB/ PCM link, 30 channels/PCM link Power Supply - 48 v DC for Exchange Ambient Temperature - 20 °C The microprocessors used in the E-10 B system are Intel 8085. A Telephone Exchange

4. URAD SWITCHING NETWORK URAD URM ETA BDA CONTROL UNIT OMC BLOCKS OF E-10 B SYSTEM Based on the functions carried by different parts, an E-10 B exchange can be divided in four blocks as shown in figure. BLOCK 2 BLOCK 1 – CONNECTION UNITS BLOCK 2 – SWITHCING NETWORK BLOCK 3 – CONTROL UNIT BLOCK 4 – OPERATION AND MANINTANENCE CENTRE BLOCK 1 BLOCK 3 E-10 B EXCHANGE STRUCTURE BLOCK 4

5. CONNECTION UNITS The connection units consists of following four types of units – Local (URAL) and Remote (URAD) subscriber connection unit Multiplex connection unit (URM) Frequency sender/receiver unit (ETA) Auxiliary equipment rack (BDA) LOCAL (URAL) / REMOTE (URAD) SUBSCRIBER CONNECTION UNIT SIGNALLING EQUIPMENT ELECTRONIC CONCENTRATION NETWORK 1024*120 PCM LINES TO SWTICHING NETWORK 1024 SUBSCRIBER LINES PCM LINES PCM LINES PCM LINES Provides connection for 1024 subscriber lines to 60, 90 or 120 digital junctions carried by 2, 3 or 4 PCM lines of 2.048 MB per sec linking it to the switching network.

6. CONNECTION UNITS Max. 1023 lines connected to unit, Equipment no. ‘0’ not used as of difficulty in addressing. Local Unit – located in same premises as exchange Remote Unit – located outside main exchange, identical construction & equipments as local unit (URAL) except few for PCBs Subscriber gain access to emergency services like police, ambulance etc. by dialing 2 digits, 6 out of 1024 equipments are used for emergency services. MULTIPLEXING CONNECTION UNIT (URM) Connected to incoming PCM links from exchanges and responsible for transmission and reception of PCM links. It has capacity of 32 PCM systems in 1 rack. Each URM – 8 modules | Each module - 4 PCMs. Two types – MRS modules and MRM modules for connection of 2.048 MB PCM links. It can process simultaneously 16 different signalling codes.

7. CONNECTION UNITS FREQUENCY SENDER / RECEIVER UNIT (ETA) Sends to switching network different binary codes which after conversion into analog in subscriber terminals become different tones or MF codes used in telephone network. E-10 B system consists of at least 2 ETAs, the maximum number of ETA being 16. Setting up of conference calls using conference circuit (CCF). Two conference circuit devices per ETA, each can set up conference connections between 3-4 subscribers. Other functions include – generation of exchange tones and reception of multi frequency signalling, push button dialing signals etc. AUXILLARY EQUIPMENT RACK This rack is regarded as a connection unit and is always given UR No. 1. It is not involved in call processing. Its functions include - Marshalling of alarms, Monitoring of recorded announcement machine operation, Management of general visual display

8. SWITCHING NETWORK A Digital switching system where signals are switched in digital form. Signals may represent speech or data. • To connect two subscribers, it is necessary to interconnect the time-slots of the two speech samples which may be on same or different PCM lines. The digitalized speech samples are switched in two modes –- • Time Switching (Different PCM lines) • Space Switching (Same PCM lines) FEATURES The time switching is used for switching of sample from one PCM to another PCM in different time slots. The time division switching network is a 3 stage system (Time – Space - Time). It provides a 4-wire switching between the time slots allocated to the calling party. Each time switch handles 16 PCM links and 4 time switches catering 4*16 = 64 PCMs are contained In one switching network rack.

9. TS SWITCHING NETWORK For example, a call sample connection is shown in the figure below. PRINCIPLE OF CONNECTION (4-WIRE) IN THE SWITHCING NETWORK TS TS Calling Subscriber Calling Subscriber (a) (b) TS Called Subscriber Called Subscriber (b) (a) Speech samples (a) from the time slot ‘I’ of the incoming network line LRE associated with the calling subscriber are switched to the time slot ‘J’ of the outgoing network line LRS associated with the called subscriber. Speech samples (b) from the time slot ‘J’ of the incoming network line LRE associated with the called subscriber are switched to the time slot ‘I’ of the outgoing network line LRS associated with the calling subscriber.

10. CONTROL UNITS These units can be classified as follows: Marker (MQ) Switching network control unit (UGCX) Multi-register (MR) Translator (TR) Charging unit (TX) MARKER Responsible for routing the messages between connection units, switching network and multi-registers. Each E-10 B is equipped with two markers working on load sharing basis. SWITCHING NETWORK CONTROL UNIT It co-ordinates operations executed by the switching network. It connects and disconnects speech channels, tones, recorded announcements and signals when ordered. There are 2 switching network control units in each marker rack.

11. CONTROL UNITS • MULTI-REGISTER • It is the heart of the system and is only control unit which can take initiative and send orders to other units. It serves new calls detected by connection units. It orders switching network to connect or disconnect two parties, orders transmission of various tones. It also receives and sends signals from/to connection units, OMC etc. Each multi-register comprises of 256 registers and an exchange contains 2-6 multi-registers depending on the traffic load. One MR has got 256 registers and out of which 254 registers are used for the setting up or releasing of calls and other two are used for house keeping purpose. • TRANSLATOR • It translates prefixes of the first digits dialled by the calling party, translates called party directory number into equipment number. It also handles all management, maintenance and test operations in conjunction with the OMC. The total capacity of translator files is 762 K words each of 16 bits, i.e. 12288 M bits. • CHARGING UNIT • It handles subscribers line accounts, computes the number of basic metered units chargeable for a given telephone call. It also sends detailed billing messages and observation messages to stand by charge recording unit (DSF) when the OMC is down or unavailable.

12. OMC PROCESSOR STORAGE UNIT MODEM • The OMC can be broadly divided into three parts – • THE PROCESSOR • THE STORAGE UNIT • THE MODEM

13. OMC PROCESSOR The processor is responsible for handling all types of various operations in the OMC. It is the unit handling the work of providing new connection , new facilities such as STD, ISD etc. STORAGE UNIT The storage unit is the part which stores data of subscriber for every second viz – the number called, the duration of the call, the place where call is made etc. and sends it to the computers for computation of detailed billing. MODEM It is the unit which connects the OMC with the other remote exchanges where it is necessary to send data from one place to another. For example: data can be send from main exchange in Durg to remote exchanges like in Bhilai.

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