Physical Transmission Media 8 5/9/ Modified by: Brierley

Objectives In this chapter, you will learn to: Characteristics of wireline transmission Properties and uses of coaxial cable Properties and uses of different types of twisted-pair wire Characteristics of lightwave transmission Properties and uses of fiber optic cable Factors to consider when selecting a telecommunications medium Cabling standards Installing wire and fiber optic cabling Testing continuity and performance on physical transmission media 5/9/ Modified by: Brierley

Characteristics of Wireline Transmission Impedance: expressed in Ohms, is the combined effect of a circuit’s inductance and capacitance. Propagation Delay and Latency: the difference in time between a data packet’s transmission and its reception over a specific route. Distortion: the unintended and undesirable modification of at least one signal component, which makes the signal different from how it was originally transmitted. Noise: any unwanted interference from external sources. 5/9/ Modified by: Brierley

Crosstalk 5/9/ Modified by: Brierley

Impulse Noise 5/9/ Modified by: Brierley

Thermal Noise 5/9/ Modified by: Brierley

Coaxial Cable 5/9/ Modified by: Brierley

Non-twisted Wire 5/9/ Modified by: Brierley

Level 1 Terminations 5/9/ Modified by: Brierley

Twisted Pair (TP) 5/9/ Modified by: Brierley

Shielded Twisted Pair (STP) 5/9/ Modified by: Brierley

Unshielded Twisted Pair (UTP) 5/9/ Modified by: Brierley

Category 5 (CAT5) 5/9/ Modified by: Brierley

Category 3 (CAT3) 5/9/ Modified by: Brierley You describe and draw

Fiber Optic Cable 5/9/ Modified by: Brierley

Fiber Optic Cable 5/9/ Modified by: Brierley

Popular Uses for Fiber Optic Cable Includes connecting: Regional and local cable TV facilities Internet NAPs with other large telecommunications exchange point Central offices with other central offices Main feeders with central offices A telecommunication’s network with private LANs A telecommunication’s network with private switching systems, such as PBX 5/9/ Modified by: Brierley

Selecting Appropriate Media When selecting telecommunications media consider: Existing infrastructure Throughput potential Cost of installation Noise immunity Security Size and scalability 5/9/ Modified by: Brierley

Comparison of Physical Media 5/9/ Modified by: Brierley

Comparison of Physical Media 5/9/ Modified by: Brierley

Structured Cabling 5/9/ Modified by: Brierley

Backbone Wiring 5/9/ Modified by: Brierley

Telecommunications Closet 5/9/ Modified by: Brierley

Telecommunications Closet 5/9/ Modified by: Brierley

Horizontal Wiring 5/9/ Modified by: Brierley

Work Area 5/9/ Modified by: Brierley

Work Area 5/9/ Modified by: Brierley

Installing UTP 5/9/ Modified by: Brierley

Crossover Cable 5/9/ Modified by: Brierley

Installation Tips for CAT5 UTP Do not untwist twisted-pair cables more than one-half inch before inserting them into the punch-down block or connector. Pay attention to the bend radius limitations for the type of cable you are installing. Test each segment of cabling as you install it with a cable tester. Use only cable ties to cinch groups of cables together 5/9/ Modified by: Brierley

Installation Tips for CAT5 UTP When pulling cable, do not exert more than 25 pounds of pressure on the cable. Avoid laying cable across the floor where it might sustain damage from rolling chairs or foot traffic. Install cable at least three feet away from fluorescent lights or other sources of EMI. Always leave slack in cable runs. 5/9/ Modified by: Brierley

Installing Fiber Splice - the physical joining of two facing and aligned pieces of wire or fiber. Mechanical splicing - the two ends of a fiber optic cable are fixed in position within a tube so that they form one continuous communications channel. Fusion splicing - a connection between fibers is accomplished through the application of heat and the resulting melting and fusion of two fiber strands. 5/9/ Modified by: Brierley

Mechanical and Fusion Splicing 5/9/ Modified by: Brierley

ST and SC Fiber Connectors 5/9/ Modified by: Brierley

Cable Installation Tips for Fiber Optic Cable When pulling fiber optic cable, do not exert pressure on the cable. Fiber optic cable should be installed within a conduit whenever you are concerned about the potential for environmental damage. Do not exceed the minimum bend radius. 5/9/ Modified by: Brierley

Troubleshooting Connectivity Problems Identify the symptoms Identify the scope of the problem Establish what has changed on the network Determine the most probable cause of the problem Implement a solution Test the solution Recognize the potential effects of the solution Document the solution 5/9/ Modified by: Brierley

Troubleshooting Tools Crossover Cable - allows you to quickly and easily verify that a node’s network adapter is transmitting and receiving signals properly. Tone Generator - a small electronic device that issues a signal on a wire pair. Tone Locator - a type of amplifier that can detect the inductive energy emitted by the tone (current) on a wire. 5/9/ Modified by: Brierley

Tone Generator and Tone Locator 5/9/ Modified by: Brierley

Performance Testers Provides the following functions: Measures the length of each wire pair Ensures that the cable does not exceed recommended maximum lengths Measures the distance from the tester to a cable fault Measures attenuation along a cable Measures crosstalk between wires 5/9/ Modified by: Brierley

Performance Testers 5/9/ Modified by: Brierley

Fiber Optic Cable Testers 5/9/ Modified by: Brierley

Time Domain Reflectometers 5/9/ Modified by: Brierley

Telephone Test Set 5/9/ Modified by: Brierley

Summary Characteristics that affect wireline transmission include impedance changes, latency, delay distortion, and noise. Traditional four-pair, non-twisted copper telephone wiring is known as Level 1 cable or quad wire. Category (CAT3) UTP cable is the minimum grade of unshielded twisted-pair cabling for use in telephone systems. To identify the source of cabling infrastructure problems, follow a logical troubleshooting methodology and have the appropriate testing tools handy. 5/9/ Modified by: Brierley