Chapter 11 Flashcards
ACR-F
Attenuation-to-Crosstalk Ratio—
Far-End
Performance parameter based on
the crosstalk measured on a
disturbed pair at the opposite end
from which the disturbing signal is
transmitted and is normalized by
the attenuation loss of the
disturbed pair wire. Formerly
referred to as equal level far-end
crosstalk (ELFEXT).
TDMM.* Page 11-6
ACR-N
Attenuation-to-Crosstalk
Ratio—Near-End
The ratio between the signal
strength arriving at the end of a
link (input to the receiver) and
the disturbance caused by the
NEXT coupling from a
disturbing wire pair.
TDMM.* Page 11-8
Attenuation
The decrease in the magnitude
of power of a transmitted signal
between two points and is used
to express the loss of optical
fiber cabling.
TDMM.* Page 11-19
CP
Consolidation Point
A connection facility within a
horizontal cabling subsystem for
interconnection of communication
cables extending from building
pathways into furniture pathways
or modular wall partitions to the
equipment outlet.
TDMM: Page G-45
Delay Skew
The difference in the
propagation delay between the
fastest and slowest pairs within
the same cable sheath.
TDMM.* Page 11-4
EMI
Electromagnetic Interference
Radiated or conducted
electromagnetic eneray that has
an undesirable effect on
electronic equipment or signal
transmissions.
TDMM: Page G-67
Fresnel Reflection
Whenever light traveling in a
material encounters a different
density material, some of the
light is reflected back to the light
source, and the rest continues.
TDMM.* Page G-84
Insertion Loss
A measurement of the loss in
signal resulting from the
insertion of a component, link, or
channel between a transmitter
and receiver.
TDMM.* Page 11-4
Insertion Loss
Deviation
A measure of the worst-case
difference in the magnitude
between the expected insertion
loss and the actual measured
insertion loss.
TDMM.* Page 71-5
MUTOA
Multi-User Telecommunications
Outlet Assembly
A grouping in one location of
several telecommunications
outlets/connectors. (T IA)
TDMM.* Page G-726
NEXT
Near-End Crosstalk
A measure of the signal coupling
between any two pairs along the
entire length of a balanced
twisted-pair cable.
TDMM.* Page 11-5
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-134
PSAACRF
Power Sum Attenuation-to-
Alien Crosstalk Ratio at Far End
A ratio in decibels (dB),
determined by subtracting the
attenuation from the power sum
alien far-end crosstalk
(PSAFEXT) loss between cables
or channels in close proximity.
TDMM.* Page G-148
PSAACRN
Power Sum Attenuation-to-Alien
Crosstalk Ratio at
Near End
A ratio in decibels (dB), determined
by subtracting the attenuation from
the power sum alien near-end
crosstalk (PSANEXT) loss between
cables or channels in close
proximity.
TDMM.* Page G-148
PSACR
Power Sum Attenuation-to-
Crosstalk Ratio
A ratio in decibels (dB), determined
by subtracting the attenuation from
the ower sum near-end crosstalk
PSNEXT) loss. PSACR is a
calculated value.
TDMM.* Page G-147
PSACRF
Power Sum Attenuation-to-
Crosstalk Ratio, Far-End
A computation of the unwanted
signal coupling from multiple
transmitters at the near end into
a pair measured at the far end
and normalized to the received
signal level.
TDMM.* Page G-147
PSANEXT
Power Sum Alien Near-End
Crosstalk
The power sum of the unwanted
signal coupling from multiple
disturbing end crosstalk pairs of
one or more 4-pair channels,
permanent links, or components to
a disturbed pair of another 4-pair
channel, permanent link, or
component, measured at
the near end.
TDMM: Page G-147
Propagation Delay
A measurement of the time
required for a signal to travel
from one end of the
transmission path to
the other end.
TDMM.* Page 11-4
Rayleigh Scattering
The scattering of light as it
travels along an optical fiber.
TDMM.* Page 11-20
Return Loss
A measurement of the reflection
of signal power resulting from
the insertion of a device in a
transmission line (in decibels).
TDMM.* Page 11-5
SNR
Signal-to-Noise Ratio
The ratio between the amount of
signal and noise (undesirable
signal) present at the receiver end
in a communications system,
expressed in decibels (dB). In
digital systems, SNR depends on
signal coding and is a determining
factor in bit error rate (BER).
TDMM.* Page G-176
TDR
Time Domain Reflectometer
A testing device that sends a
signal down a cable, then
measures the magnitude and
amount of time required for the
reflections of that signal to
return. TDRs are used to
measure the length of cables
and locate cable faults.
TDMM.* Page G-196
What is required to perform
field testing?
*Set of measurable transmission
performance parameters (or
limits)
Necessary field test
instruments
TDMM. Page 11-1
What should you do in
situations where there are
no predefined testing
requirements for
field testing?
Use the most
applicable standard.
TDMM.* Page 11-1
What does a wire map test determine?
If the individual conductors in
the cabling are connected
correctly
TDMM.* Page 11-2
Name 7 errors that can
be detected during a
wire map test.
1 .Continuity to the remote end
2.Shorts between any two or more conductors
3. Transposed pairs
4.Reversed pairs
5.Split pairs
6.Shield continuity
7.Grounded conductor
TDMM.* Page 11-2
True or False
Direct current loop
resistance is required
as an acceptance test for
balanced twisted-pair
cabling.
False. Direct current loop
resistance is NOT required as an
acceptance test for balanced
twisted-pair cabling; however, it
can be useful as a stand-alone
diagnostic test to identify a poor
contact that may be causing an
insertion loss failure.
TDMM.* Page 11-3
True or False
Characteristic impedance
is not required as an
acceptance test for
balanced twisted-pair
cabling.
True. Characteristic impedance
is not required as an acceptance
test for balanced-twisted
pair cabling.
TDMM.* Page 11-3
What method is used to
calculate the length of a
balanced twisted-pair
cable?
The TDR Method
TDMM.* Page 11-3
What formula does the TDR
use to calculate the length for
a balanced twisted pair
cable?
(Note: the maximum channel
or permanent length are
determined by the standards)
(NVP x (round-trip delay) x c x 110%)/2
TDMM.* Page 11-3
Name 3 variations in
balanced twisted-pair cable
that can result in different
propagation delays in the
cable pairs.
1 .Different twist rates
2.SlightIy different electrical
characteristics
3.Different dielectric materials
TDMM.* Page 11-3
True or False
If a field test instrument
uses the same NVP for all
pairs in a balanced twisted-
pair cable, the reported
length will be the same
for each pair.
False. If a field test instrument
uses the same NVP for all pairs
in a balanced twisted-pair cable,
the reported length will be
different for each pair.
TDMM.* Page 11-3
What term refers to the
time required for a signal to
travel from one end of the
transmission path to
the other end?
Propagation Delay
TDMM.* Page 11-4
What term describes the
difference in propagation
delay between the fastest
and slowest pairs within
the same cable sheath?
Delay Skew
TDMM.* Page 11-4
What is the relationship
between insertion loss in
decibels and system
performance?
The smaller the loss in decibels,
the better the performance.
TDMM.* Page 11-4
What ratio is used to
return loss?
The ratio of the reflected voltage
to the incident signal voltage
TDMM.* Page 11-5
What term is used describe
a ripple that appears in the
curve when attenuation
loss is plotted with
frequency?
Insertion loss deviation
TDMM.* Page 11-5
True or False
Insertion loss deviation is
not required as an
acceptance test for
balanced twisted-pair
cabling.
True. Insertion loss deviation is
not required as an acceptance
test for balanced twisted-pair
cabling.
TDMM.* Page 11-5
What is the relationship
between the value of ACR-F
in decibels and the
performance of the
cable link?
The higher the decibel level, the
better the performance of the
installed cable link.
TDMM.* Page 11-7
What does power sum
crosstalk specify?
A combination of crosstalk
from every source
TDMM.* Page 11-7
What term refers to noise
that is caused by adjacent
data communication
cables in the same bundle?
Alien crosstalk
TDMM.* Page 11-8
How are noise tests useful?
They may be useful for
troubleshooting problematic
links or channels.
TDMM.* Page 11-8
Name 2 test parameters
used to capture alien
crosstalk coupling.
1 .PSANEXT
2.PSAACR-F
TDMM.* Page 11-9
What types of faults are
TDRs primarily used
to identify?
Return loss failures
TDMM: Page 11-10
Name the 3 configurations
used for field testing
horizontal balanced
twisted-pair cabling.
1 .Channel
2.Permanent link
3.Modular plug terminated link
(MPTL)
TDMM.* Page 11-11
What does BICSI
recommend take place
before a permanent link
is tested?
*Cable should be in place.
*Both ends should be
terminated.
Outlets/faceplates should be in
place.
TDMM. Page 11-15
What is the ambient
temperature used by field
testing equipment based
on industry standards?
20 ºC (68 ºF)
TDMM.* Page 11-15
What is the defined tester
accuracy level for
category 5e and
class D cabling?
Level IIe
TDMM.* Page 11-16
What is the defined tester
accuracy level for
category 6 and class E
cabling?
Level III
TDMM.* Page 11-16
What is the defined tester
accuracy level for
category 6A and class EA
cabling?
Level IIIe
TDMM.* Page 11-16
True or False
There are no defined tester
accuracy levels for field
testers to cover the
requirements for
class F products.
True. There are no defined tester
accuracy levels for field testers
to cover the requirements for
class F products up to their
1000 MHz performance
capability.
TDMM.* Page 11-16
What does a power sum
measurement assume?
That all cables contribute
to crosstalk
TDMM.* Page 11-16
What is a bundled cable?
An assembly of two or more
cables, which may be of same or
different performance
classifications/categories
or design
TDMM.* Page 11-16
Name 2 tests that should
be considered when testing
backbone cable if the
backbone cable exceeds
the length limits used with
horizontal cabling.
1 .Continuity
2.Wire map/strand identification
TDMM: Page 11-17
What type of testing
requirements are used
when field testing
MUTOAs and CPs?
Permanent link requirements
TDMM.* Page 11-17
What should be used to
demonstrate shield
effectiveness Of installed
shielded cabling systems?
Alien crosstalk test procedures
TDMM.* Page 11-17
Name 2 applications for
coaxial cabling.
1 .Broadband applications
2.Local area networks (LANs)
(legacy)
TDMM.* Page 11-18
Name the 5 types of tests
that are most often
performed on coaxial
cable installations.
1 .Direct current loop resistance
2.1mpedance
3.Length
4.TDR
5.N0ise
TDMM.* Page 11-18
What type of coaxial
cabling is the primary type
of cabling used in
distributed antenna
systems?
50-ohm air dielectric
coaxial cable
TDMM.* Page 11-18
Name the 5 functions that
a 50-ohm cable tester
can perform.
1 . Test for continuity
2.Test for attenuation
3.Test for TDR impedance
4.Test for voltage standing radio
wave
5.Provide pass or fail test results
TDMM.* Page 11-18
Which testing tool can be
used to help identify areas
that may need additional
antennas to provide
successful coverage?
Spectrum analyzer
TDMM.* Page 11-18
What term is used to
describe loss in an optical
fiber cable?
Attenuation
TDMM.* Page 11-19
What is the recommended
method for testing optical
fiber attenuation?
Light source and power meter
TDMM.* Page 11-79
What type of tester should
be used to determine the
length of an optical
fiber cable?
OTDR
TDMM.* Page 11-79
Name 2 methods for
verifying polarity for an
optical fiber cable.
1 .OLTS
2.Visible light source
TDMM.* Page 11-19
What can result in the
OT DR underestimating the
loss for connectors
and splices?
The OTDR will underestimate
loss of connectors and splices if
it has an under-filled launch.
TDMM.* Page 11-20
How many cable ends need
to be accessible to perform
a test with an OTDR?
1
TDMM.* Page 11-20
What is the purpose of
using a launch cord with
an OTDR?
Helps measure the insertion
loss and reflectance of
the first connection
TDMM.* Page 11-20
What is the relationship
between the length of a
wavelength and the slope
of a trace produced
by an OTDR?
Shorter wavelengths produce a
steeper slope.
TDMM.* Page 11-21
Name the 3 measurements
used for the minimum level
of acceptance testing for
optical fiber cabling.
1 .Attenuation
2.Length
3.Polarity
TDMM.* Page 11-22
Which reference method
has the lowest level of
uncertainty?
The one-jumper reference
method has the lowest
level of uncertainty.
TDMM.* Page 11-22
How should premises
optical fiber cable links
be tested?
*Bidirectionally
*At their two corresponding
wavelengths
TDMM: Page 11-22
What formula is used to
calculate link attenuation?
Cable Attenuation + Connector Attenuation + Splice Attenuation
=Link Attenuation
TDMM: Page 11-22
What formula is used
to calculate cable
attenuation?
Attenuation Coefficient (dB/km) x Length (km)
=Cable Attenuation
TDMM.* Page 11-22
What formula is used
to calculate connector
attenuation?
Number of Connector Pairs (N) x Connector Loss (dB)
=Connector Attenuation (dB)
TDMM.* Page 11-23, Table 11.1
What formula is used
to calculate splice
attenuation?
Number of Splices (S) x Splice Loss (dB)
=Splice Attenuation (dB)
TDMM.* Page 11-23, Table 11.1
What is the purpose of
cable reel acceptance
testing?
To ensure that the optical fiber
cable is in good condition after
the inventory, handling, and
shipping process
TDMM.* Page 11-24
When does cable reel
acceptance testing
normally take place?
Within 5 working days of
delivery acceptance
TDMM.* Page 11-24
Why should the OLTS be
allowed to normalize to the
ambient temperature of the
testing area before
performing the test?
Helps to ensure consistent and
repeatable results
TDMM: Page 11-24
What does the attenuation
test measure?
Optical power loss between
cable termination points
TDMM.* Page 11-25
What are common issues
that will result in system
loss measurements being
higher than the calculated
link loss budget?
*Dirty connector end faces
*Connector issue
Severe bend in the cable
TDMM. Page 11-25
At what wavelengths is
end-to-end attenuation
measured for multimode
optical fiber cable?
At 850 nm and 1300 nm
TDMM.* Page 11-25
At what wavelengths is
end-to-end attenuation
measured for singlemode
optical fiber cable?
At 1310 nm and 1550 nm
TDMM.* Page 11-25
How long does the launch
cord need to be to support
an OTDR test?
Long enough to overcome the
dead zone for the optical
pulse width used
TDMM.* Page 11-26
Name 2 simple safeguards
that can be used to prevent
service disruption in an
optical fiber system.
1 .Ensure proper connector care
and cleanliness
2.Check protection of system
jumpers
TDMM.* Page 11-27
Name 4 components that
should be used to
troubleshoot and restore
optical fiber service as
quickly and easily as
possible.
- Documentation
- Inspection and cleaning rating
- Test equipment
- Troubleshooting plan
TDMM.* Page 11-27
What is a potential issue
with using wireless devices
to communicate during
testing?
Wireless devices may cause
interference with the field test
instrument during an autotest.
TDMM.* Page 11-28
How is a visible light
source used?
To test and troubleshoot the
continuity of optical
fiber strands
TDMM.* Page 11-28
What happens if a
technician uses a visual
fault locator to test an
optical fiber cable that
is broken?
The break will glow red
during the test.
TDMM.* Page 11-28
Describe how a strand
identifier works.
A strand identifier inserts a
macrobend into the optical fiber
cable, thereby allowing light
escaping from the cable
to be detected.
TDMM.* Page 11-28
