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Physical Transmission Media. 8. 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
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Physical Transmission Media 8 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 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. Modified by: Brierley
Crosstalk Modified by: Brierley
Impulse Noise Modified by: Brierley
Thermal Noise Modified by: Brierley
Coaxial Cable Modified by: Brierley
Non-twisted Wire Modified by: Brierley
Level 1 Terminations Modified by: Brierley
Twisted Pair (TP) Modified by: Brierley
Shielded Twisted Pair (STP) Modified by: Brierley
Unshielded Twisted Pair (UTP) Modified by: Brierley
Category 5 (CAT5) Modified by: Brierley
Category 3 (CAT3) You describe and draw Modified by: Brierley
Fiber Optic Cable Modified by: Brierley
Fiber Optic Cable 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 Modified by: Brierley
Selecting Appropriate Media • When selecting telecommunications media consider: • Existing infrastructure • Throughput potential • Cost of installation • Noise immunity • Security • Size and scalability Modified by: Brierley
Comparison of Physical Media Modified by: Brierley
Comparison of Physical Media Modified by: Brierley
Structured Cabling Modified by: Brierley
Backbone Wiring Modified by: Brierley
Telecommunications Closet Modified by: Brierley
Telecommunications Closet Modified by: Brierley
Horizontal Wiring Modified by: Brierley
Work Area Modified by: Brierley
Work Area Modified by: Brierley
Installing UTP Modified by: Brierley
Crossover Cable 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 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. 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. Modified by: Brierley
Mechanical and Fusion Splicing Modified by: Brierley
ST and SC Fiber Connectors 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. 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 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. Modified by: Brierley
Tone Generator and Tone Locator 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 Modified by: Brierley
Performance Testers Modified by: Brierley
Fiber Optic Cable Testers Modified by: Brierley
Time Domain Reflectometers Modified by: Brierley
Telephone Test Set 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. Modified by: Brierley