CETTMMTNL Fiber Optic Communication Module Id : TGENFOC110 1 CETTM Topics Covered Introduction to Optical Fibre Classification of Optical Fibre Application of Fibre Optic Cable Transmission Systems MTNL 2 CETTM Introduction MTNL Advantages of OF Media Low Losses in path Very high information carrying capacity Very less Transmit power required No electromagnetic interference Light weight Easy fault localization 3 Light injected into the core. Inner layer called core has a refractive index slight higher than the outer layer called cladding. This light strikes the core-cladding surface at an angle greater than the critical angle and gets reflected back into the core 4 .CETTM Introduction MTNL A Basic Optical fiber consists of two concentric layers. CETTM Introduction MTNL An Optical Fibre System uses light waves as carrier of the information signals. Main portion of an optical transmitter is light source ( LED or LASER diode. Transmitted through an Optical Fibre using the principle of Total Internal reflection. 5 . ½ Detected signal is then amplified and shaped appropriately.) This changes electrical signals to optical signals. ½ Receiver contains a photo diode which converts light back into electrical signals. Electrical signals are converted into light signals. 6 . Light travels down the fiber. Electrical signals are decoded into information. A detector changes the light signals into electrical signals.CETTM Transmission in Optical Fiber MTNL Transmission sequences given below: Information is encoded into electrical signals. Core: 8 µm diameter for SMF & 50 µm dia for MMF 2.CETTM Fiber Construction MTNL 1. 3. Cladding: 125 µm dia. Jacket: 400 µm dia 7 . Buffer: 250 µm dia. 4. CETTM Fiber Construction Secondary coating Primary coating Clad Core MTNL 9 µm 125 µm 8 . CETTM Fiber Construction MTNL Optical Fiber – Thin strands of highly transparent glass or sometimes plastic that guide light.even through curves Buffer coating or primary coating – A hard plastic coating on the outside of the fiber that protects the glass from moisture or physical damage. Core – The centre of the fiber where the light is transmitted Cladding – The outside optical layer of the fiber that traps the light in the core and guides it along . 9 . Glass Fibres [glass core & glass cladding] 2. Plastic-clad Silica Fibres [glass core & plastic cladding] 3. Single-mode fibres ½ Based on refractive index 1. Multi-mode fibres 2. Plastic Fibres [plastic core & plastic fibres] ½ Based on size 1. Step-Index Fiber 2. Graded-index Fiber 10 .CETTM Optical Fibre Classification MTNL ½ Based on material 1. CETTM Modes MTNL Single Mode Multi-mode Mode 11 . 50km Multimode fiber (MMF) has higher "light-gathering" capacity than SMF. carry many rays of light •Use for Short distance communication e.CETTM Types of Fiber Single-mode l fiber (SMF) designed to carry only a single ray of light (mode) •Use for long distance communication e. 200 mtrs MTNL 12 .g.g. 20 mtrs 13 .10.CETTM Patch Cords & Pigtails MTNL Patch Cords – It has connectors on both end – Size 5.10.20 mtrs PigTails – It has connectors on one end – Size 5. Termination Box Require at both the end of fibre cable for terminating to FDF in PCM Room One side Fiber Cable & other side Pigtails are terminated 14 . T-joint etc.g Straight Joint .CETTM O F C Joint & Termination Box Joint Box MTNL Require at every 2Km as cable drum length is limited to 2Km Should be air tight & waterproof with high tensile strength The splice joint of fiber is placed inside Different type of joint boxes are used e. Mechanical splicing Fusion Splicing 15 .Splice CETTM MTNL Permanent connection between two fibres Involves cutting of the edges of the two fibres to be spliced Alignment of the cores of the fibres to be connected is important to reduce splice loss Splicing Methods Single Fiber Mechanical splicing Adhesive bonding or Glue splicing Temp. CETTM Optical Testers MTNL Variable Attenuator Power Meter Power Meter •For Testing the output power of the Optical system or Light source Light Source Variable Attenuator •For artificially introducing The losses in fiber for Testing Light Source •For Testing the fiber losses & Fiber cuts 16 . Telephone inter–office trunk lines. Expensive environments. Undersea cables. Classified (secure) communication MTNL 17 . Rails. Military applications. Roads). Factory communication/Automation. Control systems. High EMI areas (Power lines. Customer premise communication networks. High lightning areas.CETTM Applications of Fibre Optics in Communications Common carrier nationwide networks. CETTM Elements of Fiber Optic System Optical Transmitter (E-O) Optical Receiver (O-E) Fiber Optics Optical Amplifier (O-O) Multiplexer Demultiplexer MTNL 18 . CETTM What is PDH? MTNL The Plesiochronous Digital Hierarchy (PDH) is a technology used in telecommunications networks to transport large quantities of data over digital transport equipment such as fibre optic and microwave radio systems PDH networks run in a state where different parts of the network are nearly. but not quite perfectly. synchronised 19 . but the principles are the same 20 .CETTM PDH MTNL There are three different standards of PDH European American Japanese These versions of the PDH system differ slightly in the some technical details. CETTM Limitation of PDH MTNL Existing PDH is point to point system O F capacity is under utilized Difficulty in centralized supervision Restoration of fault is time consuming Manpower requirement is more 21 . aim to provide a simple. economical and flexible telecom infrastructure 22 .CETTM What is SDH? MTNL Synchronous: One master clock and all elements synchronized with it Digital: Information in binary Hierarchy: Set of bit rates in hierarchical order SDH is an ITU-T standard for high capacity telecom network SDH is a synchronous digital transport system. to provide services quickly or to respond to new change more rapidly when networks need to improve survivability for important user services when networks need to reduce operation costs .CETTM When do we use SDH ? MTNL When networks need to increase capacity . SDH simply acts as a means of increasing transmission capacity When networks need to improve flexibility . which are becoming a heavy burden 23 . 28 Mb/s MTNL STM-1 ---------------STM-4 ---------------STM-16 -------------STM-64 -------------- Apart from the above. There is STM-0 is of 51.080 Mb/s 2488.520 Mb/s 622.CETTM SDH bit rates 155.84 Mb/s 24 .32 Mb/s 9953. DVB.A single synchronous multiplexer can perform the multiplexing function Future Proof Networking – SDH is able to handle video on demand and all other new systems like ATM. ESCON. FICON. Ethernet. etc. 25 .CETTM SDH Advantages MTNL Up gradation of system is easy Existing PDH can work on SDH Network Simplification. CETTM SDH Network Elements MTNL Terminal multiplexer Add Drop Multiplexer Regenerator Digital cross connect (DXC) 26 . The terminal is used in the chain topology as an end element E1-E4 TM STM-N STM-M 27 .CETTM SDH Network Elements MTNL Terminal multiplexer The terminal multiplexer is used to multiplex local tributaries (low rate) to the STM-N (high rate) aggregate. CETTM SDH Network Elements MTNL Add Drop Multiplexer The Add And Drop Multiplexer (ADM) passes the (high rate) stm-N through from his one side to the other and has the ability to drop or add any (low rate) tributary The ADM used in all topologies STM-N TM STM-N STM-M E1-E4 28 . CETTM SDH Network Elements MTNL Regenerator It mainly performs 3R function: 1R – Re amplification 2R – Retiming 3R – Reshaping STM-N REG STM-N 29 . CETTM SDH Network Elements MTNL Digital Cross-Connect (DXC) – Form lowest level to highest level semi-permanent interconnections between different channels and routing of them are performed STM-16 STM-4 STM-1 140 Mb/s 34 Mb/s 2 Mb/s STM-16 STM-4 STM-1 140 Mb/s Cross .connect 34 Mb/s 2 Mb/s 30 . CETTM SDH Network Topology Point to Point MTNL PDH TM STM-M STM-N TM PDH STM-M 31 . CETTM SDH Network Topology Point to Multipoint or Bus MTNL PDH TM PDH STM-N STM-N ADM TM STMM STM-M PDH STM-M 32 . ATM etc New Generation SDH can carry Ethernet .CETTM Application of SDH MTNL SDH Systems are used as a core network of service provider It is also use for access network It carries most of the Existing PDH Bit rates. etc. 33 . Gigabit Ethernet. Fast ethernet. CETTM DWDM System Components MTNL 34 . CETTM MTNL THIS SLIDE IS KEPT INTENTIONALLY BLANK 35 . CETTM MTNL THIS SLIDE IS KEPT INTENTIONALLY BLANK 36 .