Download UTP Cable Certification and Testing

Lecture 8
Cable Certification &
Testing:
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Cable Distribution
• Cable Distribution Equipment
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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
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• Multi-Mode fiber
• Single Mode Fiber
• Fiberoptic Connectors
UTP (Unshielded Twisted Pair)
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Characteristics
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Category 3
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Transmission Frequencies up to 20 MHz
Suitable for all category 3 applications as well as
16 Mbps Token Ring
Category 5
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Transmission Frequencies up to 16 MHz
intended for low speed data, telephone, 4 Mbps Token Ring, and 10 Mbps Ethernet applications.
Category 4
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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
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
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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.
TIA/EIA 568 Standard
Thin Net Coax
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(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.
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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.
Optical Fiber
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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.
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Single Mode Fiber
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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."
Fiber-optic Components
Core – inner fiber (62.5mic.)
 Cladding – encases core (125mic.)
 Jacket- surrounds core and cladding
 Strength & environmental members
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Indoor Fiber-optic Cables
Fiber-optic Connectors
ST
 SC
 FSD
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Fiber Termination
Techniques
 Breakout
Cable
Epoxy
 Crimp
 UV Cure Epoxy
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Air Blown Fiber
Transceivers
 AUI connectors
 Media converters
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Testing & Certification
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UTP Cable Certification and Testing
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Attenuation & Next
Pair Scanners
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Standards
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TSB-67 “Transmission Performance
Specifications for Field Testing of Unshielded
Twisted-Pair Cabling Systems”
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568-A
UTP Properties
Attenuation
 Next
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Attenuation and Near End Cross Talk (NEXT) are the two most
crucial electrical parameters that distinguish performance
characteristics of twisted pair cable.
Attenuation
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Attenuation refers to the power loss an electrical signal
experiences as it travels through a cable.
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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.
Near End Cross Talk (NEXT)
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NEXT occurs when a portion of the signal energy jumps
from one pair in a cable to another.
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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.
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Too much signal "noise" prevents the receiver from
distinguishing transmit form receive signals and results in
garbled transmission and poor network performance.
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Attenuation to Cross Talk margin
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Attenuation per 100m
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NEXT
Peak Frequency
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Category 3
13.1 dB
23 dB
16 MHz
Category 4
8.9 dB
38 dB
20 MHz
Category 5
8.2 dB
44 dB
100 MHz
Pair Scanners
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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/cablete
sts/lb121-1.html