INTERNSHIP REPORT

Pakistan telecommunication company ltd :

The Report is prepared of 3 weeks for PTCL Transmission

Submitted to: (Mam: Pray).

Submitted By: (1) Muhammad Noman

(2) Soofi Mohsin Hassan

(3) Asif Ali Channa

(4) Shams Gul

Department of BS-Telecommunication

University of Sindh Jamshoro

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Table of ContentsOrganizational introduction …………………………………….. 3

Introduction and Historical Background of PTCL …………………………… 3

Transmission ……………………………………………………….. 5Optical Fiber ……………………………………………………………………………………… 6

Optical Fiber Connector ……………………………………………………………………… 7

Splicing ………………………………………………………………………………………………. 8

Signal …………………………………………………………………………………………………. 9

Channel-Associated Signaling (CAS) ……………………………………………………….. 9Common-Channel Signaling (CCS) ………………………………………………………….. 9Synchronous Digital Hierarchy (SDH) ……………………………………………………… 10ONU (Optical Network Unit) ……………………………………………………………………. 11Broadcast Domain …………………………………………………………………………………… 39

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ORGANIZATIONAL INTRODUCTION

Introduction & Historical Background of PTCLPTCL is largest telecommunication company of Pakistan. It has reached its service to almost every part of the country. (PTCL) is proud to be Pakistan’s most reliable and largest converged services carrier providing all telecommunications services from basic voice telephony to data, internet, video-conferencing and carrier services to consumers and businesses all over the country with more the 2000 exchanges all providing at least the fixed line network and the dialup internet service.

Whether it is an office in the largest city of Pakistan or a home in a small village, PTCL is present in every corner of Pakistan to serve its customers providing several services.

Some of its services are named below: Broadband IPTV EVO Wireless Dialup Internet

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TelephonePTCL is established since 1947 by establishing Posts and Telegraph’s Department, proceeding to establishing Pakistan Telegraph and Telephone Department in 1961, then in 1990-91, it went to become Pakistan Telecom Corporation, after which in 1996, PTCL became listed in all stock exchanges of Pakistan, further in 1998, its subsidiaries of Mobile Services, and Internet Services started on the name of Ufone and PakNet, coming to the year 2000, it Finalized its Telecom Policy. It also announced in year 2003, the Telecom Deregulation Policy, finally in 2006, Etisalat (The Telecom Company of United Arab Emirates) took over its Management and it is still holding the status of backbone for country's telecommunication infrastructure despite arrival of a dozen other telecoms including telecom giants like Telenor, China Mobile, Wateen Telecom, and others.

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TransmissionIn telecommunications, transmission (abbreviation: Tx) is the process of sending and propagating an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless. Transmission technologies and schemes typically refer to physical layer protocol duties such as modulation, demodulation, line coding, equalization, error control, bit synchronization and multiplexing, but the term may also involve higher-layer protocol duties, for example, digitizing an analog message signal, and source coding (compression).Transmission of a digital message, or of a digitized analog signal, is known as data transmission or digital communication.One transmission is the sending of a signal with limited duration, for example a block or packet of data, a phone call, or an email.

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Optical Fiber optical fiber (oroptical fibre) is a flexible, transparent fiber made of high quality extruded glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe” to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. This causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter, and are used

for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are

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used for most communication links longer than 1,050 meters (3,440 f t).Joining lengths of optical fiber is more complex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together, either mechanically or by fusing them with heat. Special optical fiber connectors for removable connections are also available.

Optical fiber connectorAn optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors lose very

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little light due to reflection or misalignment of the fibers. In all, about 100 fiber optic connectors have been introduced to the market.

Splicing:Fiber splicing is the process of permanently joining two fibers together. Splices are "permanent" connections between two fibers.There are two types of fiber splicing, Mechanical splicing and Fusion splicing.

Mechnical Splicing:Mechanical Splices are alignment gadget that hold the ends of two fibers together with some index matching gel or glue between them, enabling light to pass from one fiber into the other.Fusion Splicing:Fusion splicing is the act of joining two optical fibers end-to-end using heat.  The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered or reflected back by the splice, and so that the splice and the region surrounding it are almost as strong as the virgin fiber itself. The source of heat is usually an electric arc, but can also be a laser, or a gas flame, or a tungsten filament through which current is passed. Fusion splicing is the most widely used method of splicing as well as providing the strongest and most reliable joint between two fibers.

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SignalA function that conveys information about the any physical behavior or attributes of some phenomenon.Signaling:In telecommunication, signaling has the following meanings:1. The use of signals for controlling communications.2. The information exchange concerning the establishment

and control of a telecommunication circuit and the management of the network, in contrast to user information transfer.

3. The sending of a signal from the transmitting end of a telecommunication circuit to inform a user at the receiving end that a message is to be sent.

Channel-associated signaling:Channel-associated signaling (CAS), also known as per-trunk signaling (PTS), is a form of digital communication signaling.Definition:It uses routing information to direct the payload of voice or data to its destination.With CAS signaling, this routing information is encoded and transmitted in the same channel as the payload itself. This information can be transmitted in the same band or a separate band to the payload.

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CAS potentially results in lower available bandwidth for the payload. For example, in the PSTN the use of out-of-band signaling within a fixed bandwidth reduces a 64k bit/s DS0 to 56k bit/s.Security benefits: of separating the control lines from the payload.Application: Robbed-bit signaling.Common-channel signaling:Definition:Common-channel signaling (CCS) is the transmission of signaling information (control information) on a separate channel from the data, and, more specifically, where that signaling channel controls multiple data channels. For example, in the public switched telephone network (PSTN) one channel of a communications link is typically used for the sole purpose of carrying signaling for establishment and tear down of telephone calls. The remaining channels are used entirely for the transmission of voice data. In most cases, a single 64kbit/s channel is sufficient to handle the call setup and call clear-down traffic for numerous voice and data channels. The logical alternative to CCS is channel-associated signaling (CAS), in which each bearer channel has a signaling channel dedicated to it.

Synchronous Digital Hierarchy (SDH)Short for an Synchronous Digital Hierarchy international standard for synchronous data transmission over fiber optic cables. The North American equivalent of SDH is SONET. SDH is a standard technology for synchronous data transmission on optical media. It is the international equivalent of Synchronous Optical Network. Both technologies

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provide faster and less expensive network interconnection than traditional PDH (Plesiochronous Digital Hierarchy) equipment.

In digital telephone transmission, "synchronous" means the bits from one call are carried within one transmission frame. "Plesiochronous" means "almost (but not) synchronous," or a call that must be extracted from more than one transmission frame.SDH uses the following Synchronous Transport Modules (STM) and rates: STM-1 (155 megabits per second), STM-4 (622 Mbps), STM-16 (2.5 gigabits per second), and STM-64 (10G bps).Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy(SDH) are standardized protocols that transfer multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates data can also be transferred via an electrical interface. The method was developed to replace the Plesiochronous Digital Hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without synchronization problems.

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ONU (Optical Network Unit)An Optical Network Unit (ONU) converts optical signals transmitted via fiber to electrical signals. These electrical signals are then sent to individual subscribers. ONUs are commonly used in fiber-to-the-home (FTTH). The ONU is at the subscriber end and converts the optical signal to whatever the "last mile" format is (DSL, Ethernet, etc.).Broadcast domain:A broadcast domain is a logical division of a computer network, in which all nodes can reach each other by broadcast at the data link layer. A broadcast domain can be within the same LAN segment or it can be bridged to other LAN segments.In terms of current popular technologies: Any computer connected to the same Ethernet repeater or switch is a member of the same broadcast domain. Further, any computer connected to the same set of inter-connected switches/repeaters is a member of the same broadcast domain. Routers and other higher-layer devices form boundaries between broadcast domains.This is as compared to a collision domain, which would be all nodes on the same set of inter-connected repeaters, divided by switches and learning bridges. Collision domains are generally smaller than, and contained within, broadcast domains.While some layer two network devices are able to divide the collision domains, broadcast domains are only divided by layer 3 network devices such as routers or layer 3 switches. Separating VLANs divides broadcast domains as well, but provides no means to network these without layer 3 functionality.

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Digital Subscriber line Access Multiplexer (DSLAM)

A digital subscriber line access multiplexer (DSLAM, often pronounced dee-slam) is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques.[The DSLAM equipment collects the data from its many modem ports and aggregates their voice and data traffic into one complex composite "signal" via multiplexing. Depending on its device architecture and setup, a DSLAM aggregates the DSL lines over its Asynchronous Transfer Mode (ATM), frame relay, and/or Internet Protocol network (i.e., an IP-DSLAM using PTM-TC [Packet Transfer Mode - Transmission Convergence]) protocol(s) stack.The aggregated traffic is then directed to a telco's backbone switch, via an access network (AN), also called a Network Service Provider (NSP), at up to 10 G bit/s data rates.

Main Distribution Frame (MDF )

a main distribution frame (MDF or main frame) is a signal distribution frame for connecting equipment (inside plant) to cables and subscriber carrier equipment (outside plant). The MDF

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is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires at the MDF. All cable copper pairs supplying services through user telephone lines are terminated at the MDF and distributed through the MDF to equipment within the local exchange e.g. repeaters and DSLAM. Cables to intermediate distribution frames terminate at the MDF. Trunk cables may terminate on the same MDF or on a separate trunk main distribution frame (TMDF).

Like other distribution frames the MDF provides flexibility in assigning facilities, at lower cost and higher capacity than a patch panel.

The most common kind of large MDF is a long steel rack accessible from both sides. On one side, termination blocks are arranged horizontally at the front of rack shelves. Jumpers lie on the shelves and go through an insulated steel hoop to run vertically to other termination blocks that are arranged vertically. There is a hoop or ring at the intersection of each level and each vertical. Installing a jumper requires two workers, one on each side. The shelves are shallow enough to allow the rings to be within arm's reach, but the workers prefer to hang the jumper on a hook on a pole so their partner can pull it through the ring. A fanning strip at the back of each termination block prevents the wires from covering each other's terminals. With disciplined administration the MDF can hold over a hundred thousand jumpers, with dozens changed every day, for decades without tangling

Pulse-Code Modulation

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Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, Compact Discs, digital telephony and other digital audio applications. In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps.

Linear pulse-code modulation (LPCM) is a specific type of PCM where the quantization levels are linearly uniform.[5] This is in contrast to PCM using, for instance, A-law algorithm or μ-law algorithm where quantization levels vary as a function of amplitude. Though PCM is a more general term, it is often used to describe data encoded as LPCM.

PCM streams have two basic properties that determine their fidelity to the original analog signal: the sampling rate, which is the number of times per second that samples are taken; and the bit depth, which determines the number of possible digital values that each sample can take.

Digital Distribution frameIn telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made.

For example, the Main Distribution Frame (MDF) located at a telephone central office terminates the cables leading to subscribers on the one hand, and cables leading to active equipment (such as DSLAMs and telephone switches) on the other. Service is provided to a subscriber by manually wiring a twisted pair (called a jumper wire) between the telephone line and the relevant DSL or POTS line circuit.

In broadcast engineering, a distribution frame is a location within an apparatus room through which all signals (audio, video, or data) pass, with the ability to arbitrarily route and connect sources and destinations between studios and other internal and external points. Connections can either be soldered, or made using terminal blocks. Because the frame may carry live broadcast signals, it may be considered part of the airchain.

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