Chapter 6 Flashcards
AWG
American Wire Gauge
A system used to specify wire
size. The greater the wire
diameter, the smaller
the AWG value.
TDMM.* Page G-8
Balanced Twisted-
Pair
A multi-conductor
communications cable
composed of two or more
copper conductors twisted in a
manner designed to cancel
electrical interference.
TDMM.* Page G-78
Bandwidth
A range of frequencies available
for signaling expressed in hertz
(Hz). It is used to denote the
potential information handling
capacity of the medium, device,
or system.
TDMM.* Page G-18
Cable
1 .An assembly of one or more
insulated conductors or optical
fibers within an enveloping
sheath that may be screened or
unscreened.
2. The act of installing
communications cable.
TDMM.* Page G-27
Cable Assembly
A cable that has connectors
installed on one or both ends.
TDMM.* Page G-27
Capacitance
1 . The ability of an electronic
component to store electrical
energy.
2. The opposition to a change in
voltage.
TDMM: Page G-30
Chromatic Dispersion
A result of the phenomenon that
the velocity of propagation in a
medium is frequency dependent,
which causes the frequency
components of a pulse to lose
phase coherence as it
propagates (e.g., transmitted
pulse will spread out as it
propagates).
TDMM: Page G-36
Coaxial Cable
A cable consisting of a central
metallic inner conductor
separated from an enclosing
outer conductor by a dielectric
material. This material may be
solid, foam, suitable gas, or dry
air. The outer conductor
comprises a metallic braid, a foil
layer, or a combination
of braid and foil.
TDMM.* Page G-39
Conductance
The measure of the ease with
which electrical current flows
through a conductor. Uniformly
distributed along the conductor
length, conductance varies as a
function of a conductor’s geometry
and the dielectric properties of the
materials surrounding the
conductor. One of the primary
parameters for transmission lines.
The inverse of resistance. The unit
of measure is siemens (S).
TDMM.* Page G-44
Connector
A mechanical device used to
provide a means for aligning,
attaching, and achieving
continuity between conductors
or optical fibers.
TDMM.* Page G-45
Crosstalk
The unwanted transfer of signal
from one or more circuits to
other circuits as a result of
electromagnetic interference
TDMM.* Page G-50
Delay Skew
The difference in propagation
delay between any two balanced
twisted-pairs within the same
cable sheath. (T IA)
Usually used in reference to the
delay between the balanced
twisted-pair with the highest and
the lowest signal propagation
delay value.
TDMM.* Page G-54
Dispersion
1 . The loss of signal resulting from
the scattering of light pulses as
they are transmitted through a
medium.
2. The widening or spreading out of
the modes in a light pulse as it
progresses along an optical fiber.
3. The characteristics of the sound
coverage field of a speaker.
TDMM.* Page G-60
EMI
Electromagnetic Interference
Radiated or conducted
electromaanetic energy that has
an undesirable effect on
electronic equipment or signal
transmissions.
TDMM.* Page G-67
Inductance
1 . The property of an electrical
force field built around a
conductor when current flows
through it.
2. The resistance to change in
current.
TDMM.* Page G-95
Inside Plant (ISP)
Inside Plant
Infrastructure
(telecommunications) systems
(e.g., balanced twisted-pair cabling,
optical fiber cabling, coaxial
cabling, racks, cabinets, cabling
pathways, information outlets)
inside a building.
Telecommunications companies
refer to this as inside wire (IW) or
intrafacility cabling (IFC).
TDMM.* Page G-98
Modal Dispersion
A characteristic of transmission
in an optical fiber that results
from different lengths of the
light paths taken by the many
modes of light as they travel
down the fiber from source to
receiver. Also called modal
distortion.
TDMM.* Page G-122
NVP
Nominal Velocity of Propagation
The coefficient used to determine
the speed of transmission along
a cable relative to the speed of
light in a vacuum, typically
expressed as a percentage. Also
called phase velocity and velocity
of propagation.
TDMM.* Page G-130
OTDR
Optical Time Domain
Reflectometer
An instrument that measures
transmission characteristics of
optical fiber by measuring the
backscatter and reflection of
injected light as a function of time.
Used to measure attenuation of
optical fiber, splices, and
connectors and locate faults.
TDMM.* Page G-734
Optical Fiber
A transmission media using a
thin filament of glass or plastic
use to transport pulse light
signals. Its bandwidth is higher
than copper and not subject to
electromagnetic interference
(EMI). The optical fiber consists
of a central core (glass or
plastic) and an outer cladding.
TDMM.* Page G-734
OSP
Outside Plant
1 . Telecommunications
infrastructure designed for
installation exterior to buildings
and is typically routed into the
entrance facility. (T IA)
2.Communications infrastructure
outside of the buildings/premises
usina underaround conduits and
vaulfs, direct-buried cable, aerial
plants, and wireless.
TDMM.* Page G-135
Plenum
The areas throughout the building,
compartment, or chamber to
which one or more air ducts are
connected, forming part of the air
distribution system.
TDMM.* Page 6-27
Resistance
A measure of opposition a
material offers to the flow of direct
current. Measured in ohms.
TDMM: Page
Riser
Any vertical service ducts
(shafts and chambers) and the
interfloor passages of the
building subject to the
cable installation.
TDMM.* Page 6-27
What are the components
of a cabling system?
Cables, equipment cords, patch
cords, and connecting hardware
components
TDMM.* Page 6-1
What is the difference
between an equipment
cord and a patch cord?
1 .Equipment cords attach
directly to active equipment
(e.g., network switch,
computer).
2.Patch cords are used to cross-
connect passive cabling
infrastructure (e.g., patch panel
to patch panel).
TDMM: Page 6-1
Name the 2 general
environmental styles of
balanced twisted-pair and
optical fiber cabling.
1 .Outside plant (OSP)
2. Premises (Inside plant [ISP])
TDMM.* Page 6-1
Which IEC standard
specifies an international
classification system for
the sealing effectiveness of
enclosures for electrical
equipment against
intrusion into the
equipment of foreign
bodies and moisture?
IEC 60529
TDMM.* Page 6-2
What term does ISO/IEC
use to describe channel
and link performance?
Class
TDMM.* Page 6-3, Table 6.1
What term does ISO/IEC
use to describe cable and
connecting hardware
performance?
Category
TDMM.* Page 6-3, Table 6.1
What term does TIA
use to describe
performance levels for
cabling and cabling
components?
Category
TDMM.* Page 6-3, Table 6.1
What is the minimum
acceptable performance
level for network cabling?
Category 5e/cIass D
TDMM.* Page 6-3
What does BICSI
recommend as the
minimum performance
level for horizontal
balanced twisted-pair
cabling?
Category 6A/class EA
TDMM.* Page 6-3
Per TIA standards, what is
the maximum frequency at
which category 3 cable
can operate?
16 MHz
TDMM.* Page 6-4, Table 6.2
Per TIA standards, what is
the maximum frequency at
which category 5e cable
can operate?
100 MHz
TDMM.* Page 6-4, Table 6.2
Per TIA standards, what is
the maximum frequency at
which category 6 cable
can operate?
250 MHz
TDMM.* Page 6-4, Table 6.2
Per TIA standards, what is
the maximum frequency at
which category 6A cable
can operate?
500 MHz
TDMM.* Page 6-4, Table 6.2
Per ISO standards, what is
the maximum frequency at
which category 7/class F
cable can operate?
600 MHz
TDMM.* Page 6-4, Table 6.2
Per ISO standards, what is
the maximum frequency at
which category 7A/class F
cable can operate?
1000 MHz
TDMM.* Page 6-4, Table 6.2
Per ISO standards, what is
the maximum frequency at
which category 8.1/class I
cable can operate?
2000 MHz
TDMM.* Page 6-4, Table 6.2
Per ISO standards, what is
the maximum frequency at
which category 8.2/class II
cable can operate?
2000 MHz
TDMM.* Page 6-4, Table 6.2
ISO/IEC uses an x/y
designation to describe
balanced twisted-pair
cables. What do the letters
represent?
*X = Overall screen type
Y = Individual pair screen type
TDMM. Page 6-4
True or False
The ANSI/TIA standards
provide clear cable design
designations.
False. The ANSI/TIA standards
do not provide clear cable
design designations.
TDMM.* Page 6-4
What are the 2 most
frequently used ANSI/TIA
cable designations?
UTP
ScTP
TDMM.* Page 6-4
True or False
Cable design designations
can be applied to connecting
hardware in the same manner
as cable.
False. Designations cannot be
applied in the same manner to
connecting hardware because of
significant design differences.
TDMM.* Page 6-4
How should connecting
hardware be referenced
in general?
As unscreened or screened.
UTP, STP, or FTP may be
appropriate as well.
TDMM.* Page 6-4
What is the characteristic
impedance of balanced
twisted-pair cable?
100 ohms (±15 ohms)
TDMM.* Page 6-7
What conductor sizes are
used for balanced twisted-
pair cable?
22 to 26 AWG
TDMM.* Page 6-7
Name 3 components found
in all balanced twisted-pair
cabling.
1 . Solid or stranded conductors
2. Thermoplastic insulation
3. Outer jacket or sheath
TDMM.* Page 6-8
How is efficient
insulation defined?
As material where any loss of
the transmitted signal because
of loss associated with the
insulation is minimal
TDMM: Page 6-8
Name 2 factors that affect
the mutual capacitance of
a balanced twisted-pair
cable.
1 . The conductor’s insulating
material
2. The insulation’s thickness
TDMM.* Page 6-9
What does permittivity
indicate?
Insulation’s ability to transmit
(or permit) an electric field
TDMM.* Page 6-9
Name the 4 primary
parameters that control the
transmission performance
of a cable.
1 .Resistance (R)
2. Conductance (G)
3. Inductance (L)
4. Capacitance (C)
TDMM.* Page 6-10
Name 6 secondary
parameters that affect the
transmission performance
of a cable.
1.lnsertion loss
2.Crosstalk loss
3.Return loss (RL)
4.Propagation delay
5.Propagation delay skew
6.Nominal velocity of propagation (NVP)
TDMM.* Page 6-10
Name 4 mechanical
characteristics that may
influence transmission
performance.
1 . Tensile strength
2. Temperature rating
3.FlammabiIity rating
4.Environmental impact resistance
TDMM.* Page 6-10
True or False
Screened cables radiate less
electromagnetic energy than
unscreened cables.
True. Screened cables radiate
less electromagnetic energy
than unscreened cables.
TDMM.* Page 6-71
Name 2 common styles of
screening used in balanced
twisted-pair cables.
1.Foil
2.Braid
TDMM.* Page 6-11
Name 3 functions
performed by a cable
screen/shield.
1 .Reduces the level of the signal
radiated from the cable.
2.Minimizes the effect of
external EMI on the cable pairs.
3.Provides physical protection.
TDMM.* Page 6-11
Name 3 factors that
determine a screen’s
effectiveness.
- Material type
- Thickness
- Relative coverage
TDMM.* Page 6-11
What type of
electromagnetic field is
typically blocked by foil?
Higher frequency
(30 MHz and higher)
TDMM.* Page 6-11
What type of
electromagnetic field is
effectively blocked by
copper braid?
Lower frequency
(below 30 MHz)
TDMM.* Page 6-11
What type of
electromagnetic field is
effectively blocked by solid
metal tubing blocks?
Almost any electromagnetic fields
TDMM.* Page 6-71
What is the purpose of a
drain wire?
To drain the current
induced on the screen
TDMM.* Page 6-11
What type of screen provides
the highest level of protection
in an environment with
unusually strong effects from
relatively low-frequency EMI?
A combination of braid and foil
screens provides the highest
level of protection.
TDMM.* Page 6-12
What is the only type of
screen that is effective at
very low frequencies
(less than 1 kHz)?
Thick-wall metal conduit
TDMM.* Page 6-12
What type of screen is a
better choice in an
environment with unusually
strong effects from relatively
high-frequency EMI?
Foil screen
TDMM.* Page 6-12
True or False
Multipair screened cabling
is recognized for use in
horizontal and backbone
cabling applications.
False. Multipair screened cabling
is recognized for use in backbone
cabling applications only.
TDMM.* Page 6-12
Why do balanced twisted-
pair patch cords typically
have stranded conductors?
For added flexibility
TDMM.* Page 6-12
Balanced twisted-pair
patch cords that are
stranded may exhibit
_ percent to _ percent
more attenuation than
solid conductors.
Balanced twisted-pair patch cords
that are stranded may exhibit
20 percent to 50 percent
more attenuation than solid
conductors.
TDMM.* Page 6-12
What types of connectors
are typically used on the
ends of balanced twisted-
pair patch cords?
8-position, 8-contact (8P8C)
TDMM.* Page 6-12
What term is used to
describe cords that directly
attach to equipment on one
or both ends?
Equipment cord
TDMM.* Page 6-13
What term is used to
describe cords that attach
one set of connecting
hardware to another set of
connecting hardware to
form a cross-connection?
Patch cord
TDMM.* Page 6-13
Which type of patch cord, solid
or stranded conductor,
typically features better
insertion loss characteristics?
Solid
TDMM.* Page 6-13
Which type of patch cord, solid
or stranded conductor,
typically features better flex
life characteristics?
Stranded
TDMM: Page 6-13
What is the primary
difference between twisted-
pair and optical fiber cables?
Optical fiber uses pulses of light
to transmit signals whereas
balanced twisted-pair uses an
electron flow.
TDMM.* Page 6-74
Name the 2 classifications
of optical fiber cable.
1 .Singlemode
2.Multimode
TDMM.* Page 6-74
What is the core diameter
of a singlemode fiber?
8 to 11 um
TDMM.* Page 6-14
What is the approximate
cladding diameter of a
singlemode fiber?
125 um
TDMM.* Page 6-14
What are the common core
diameters for multimode
fibers?
50 um or 62.5 um
TDMM.* Page 6-74
What is the approximate
cladding diameter of a
multimode fiber?
125 um
TDMM.* Page 6-14
What 3 classification terms
are used to describe an
optical fiber cable?
- Indoor/outdoor optical fiber
cable - Indoor optical fiber cable
- Outdoor optical fiber cable
TDMM.* Page 6-76 .
What is the recommended use
for 62.5 um core fiber cable?
For extensions to existing
installations only
TDMM.* Page 6-16
What common wavelengths
are supported by multimode
optical fiber cable?
*850 nm VCSEL
1300 nm LED
TDMM. Page 6-76
What is the maximum distance
for running singlemode optical
fiber cable in structured
cabling systems?
3000m (9840 ft)
TDMM.* Page 6-17
What type of light source is
typically used with singlemode
optical fiber cable?
A laser light source
TDMM.* Page 6-17
What common wavelengths
are supported by singlemode
optical fiber cable?
1310 nm
1490 nm
1550 nm
1625 nm
TDMM.* Page 6-17
Name 3 causes of attenuation
in optical fiber cable.
1 .GIass material, impurities, and
point defects
2.Macrobends and microbends
in the fiber strands
3.Nuclear radiation (point
defects) (only in rare cases)
TDMM.* Page 6-17
Optical fiber attenuation is _____
proportional to length
Optical fiber attenuation is
directly proportional to length.
TDMM.* Page 6-17
What does the modal
bandwidth of multimode
optical fiber provide?
A measure of the amount of
information an optical fiber is
capable of transporting
TDMM.* Page 6-78
How is the modal
bandwidth of multimode
optical fiber defined?
As the frequency at which the
light pulse amplitude drops 3 dB
at an -1 km (0.625 mi) distance
TDMM.* Page 6-18
How will increasing the length
affect the information-carrying
capacity of an optical fiber
cable?
Increasing cable length will lower
the information-carrying capacity
of the optical fiber cable.
TDMM.* Page 6-78
Name the 2 components
that are used to determine
overall bandwidth.
1 .Modal dispersion
2.Chromatic dispersion
TDMM.* Page 6-78
From a practical point of
view, how is the bandwidth
of singlemode optical fiber
described?
As unlimited
TDMM.* Page 6-78
Where is loose-tube optical
fiber cable primarily used?
Outdoors
TDMM.* Page 6-19
What is the most common
diameter for a loose-tube
optical fiber cable?
250 um
TDMM.* Page 6-19
What are the 2 main
functions of a cable jacket
on an optical fiber cable?
1 .Physical protection for the
optical fibers in the cables
2.EnvironmentaI protection for
the optical fibers in the cable
TDMM.* Page 6-79
Name 3 advantages of
loose-tube optical fiber
cable compared to tight-
buffered cables with the
same number of strands.
1 .A greater tensile strength and
more robust outer jacket
2.A greater resistance to low-
temperature effects on
attenuation
3.A cable jacket that expands
and contracts with changes in
temperature without affecting
the optical fiber
TDMM.* Page 6-20