Lecture 8 Cable Certification & Testing:

1. Lecture 8 Cable Certification & Testing:

2. Cable Distribution • Cable Distribution Equipment • UTP (Unshielded Twisted Pair) • UTP Cable Termination Tools • UTP Connectors, plugs, jacks, and patch Panels • UTP Cable Certification and Testing • Shielded Twisted Pair • Thin-Net Coaxial Cable • Optical Fiber • Multi-Mode fiber • Single Mode Fiber • Fiberoptic Connectors

3. UTP (Unshielded Twisted Pair) • Characteristics • Four Pair, 24 Gauge 100 Ohm copper cable • Unbalanced • PVC or Plenum Jacket • Types of UTP Cable: Category 3, 4, 5, and "Enhanced Category 5" or Category 6 • Category 3 • Transmission Frequencies up to 16 MHz • intended for low speed data, telephone, 4 Mbps Token Ring, and 10 Mbps Ethernet applications. • Category 4 • Transmission Frequencies up to 20 MHz • Suitable for all category 3 applications as well as • 16 Mbps Token Ring • Category 5 • Transmission Frequencies up to 100 Mhz • Most popular for high speed applications • Suitable for all Category 3 and 4 applications as well as any copper based voice, video, or data application such as: 100 Mbps "Fast Ethernet", CDDI (FDDI over Copper), and ATM. • Enhanced Category 5 and Category 6 • High frequency applications such as Gigabit Ethernet and certainly ATM will require better and higher bandwidth cables than originally specified by the Category 5 standard. While Gigabit Ethernet should be compatible with Category 5 cabling, it is suggested that cabling for high speed applications including Fast Ethernet should exceed Category 5 standards. • New standards for such cabling is underway.

4. TIA/EIA 568 Standard

5. Thin Net Coax • (Coaxial Cable) Used for 10Base 2 Ethernet. • Coax is primarily used for its self shielding properties, low attenuation at LAN frequencies, and installation expense. • The construction of the cable greatly reduces susceptibility to outside interfering signals and noise, as well as minimizing the radiated emissions from the cable.  • Jacket- (sheath) The outer protective covering of a cable. • Center Conductor   Inner part of a Thin- net (coaxial cable). Center conductor or wire on which the LAN signal is carried. See Thin-net, shield, braided wire shield, foil shield, 10Base 2." • Insulation   A material which is nonconductive to the flow of electric current. The coating (usually plastic) of a conductor which insulates it from other conductors. • Shield   A metallic foil or multi-wire screen mesh that is used to prevent electromagnetic fields from penetrating or exiting a transmission cable.

7. Optical Fiber • Multi-Mode fiber • most commonly used in LANs and MANs. • A fiber wave guide which supports the propagation of multiple modes. • Multi-mode fiber may have a typical core diameter of 50 to 100 um with a refractive index that is graded or stepped. • It allows the use of inexpensive LED light sources and connector alignment and coupling is less critical than with single mode fiber. • Distances of transmission and transmission bandwidth are less than single mode fiber due to dispersion of the light signal.

9. Single Mode Fiber • A fiber wave guide in which only one mode will propagate. Single mode fiber has a very small core diameter, in some fibers aprox. 8 micron. It allows signal transmission for long fiber distances with relatively high bandwidth and is generally driven with a laser diode."

11. Fiber-optic Components • Core – inner fiber (62.5mic.) • Cladding – encases core (125mic.) • Jacket- surrounds core and cladding • Strength & environmental members

14. Indoor Fiber-optic Cables

15. Fiber-optic Connectors • ST • SC • FSD

17. Fiber Termination Techniques • Breakout Cable • Epoxy • Crimp • UV Cure Epoxy • Air Blown Fiber

18. Transceivers • AUI connectors • Media converters

20. Testing & Certification • UTP Cable Certification and Testing • Attenuation & Next • Pair Scanners

21. Standards • TSB-67 “Transmission Performance Specifications for Field Testing of Unshielded Twisted-Pair Cabling Systems” • 568-A

22. UTP Properties • Attenuation • Next • Attenuation and Near End Cross Talk (NEXT) are the two most crucial electrical parameters that distinguish performance characteristics of twisted pair cable.

23. Attenuation • Attenuation refers to the power loss an electrical signal experiences as it travels through a cable. • Communications equipment operates by detecting signal variations (which becomes more difficult as the signal becomes weaker). • In a Category 5 system TIA/EIA 568A limits attenuation to 24 dB for 100 MHz signal. • 20 db of attenuation means that only 1/100 th of the original signal reaches its destination. • the lower the dB means the stronger the signal • Distance, higher frequencies and high temperatures increase attenuation.

24. Near End Cross Talk (NEXT) • NEXT occurs when a portion of the signal energy jumps from one pair in a cable to another. • Cables are most susceptible to cross talk near their ends, or close to devices. • In a UTP cable one or two pairs are used to transmit signals while the other pair or pairs receive. • Close proximity of the transmit pairs increases NEXT. • The first 50 or 60 ft of a cable run are the most susceptible to NEXT. • Cross connects are especially susceptible to NEXT.

25. Too much signal "noise" prevents the receiver from distinguishing transmit form receive signals and results in garbled transmission and poor network performance. • Attenuation to Cross Talk margin • Category 3 Category 4 Category 5 • Attenuation per 100m 13.1 dB 8.9 dB 8.2 dB • NEXT 23 dB 38 dB 44 dB • Peak Frequency 16 MHz 20 MHz 100 MHz

26. Pair Scanners • Pair Scanners • CAT 5 Pair Scanner (Cable Tester) • CAT 5 Pair Scanners Differ from normal Pair Scanners in that they test all pairs of the cables at various frequencies up to 100 MHz. • Measures each pair for Distance (Including Twist Pitch) • http://www.humboldt.edu/~mdh3/network/netlab/cabletests/lb121-1.html