Chapter 12 Field Testing & Structured Cabling

Question 1

ACR-F

Answer 1

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 12-7

Question 2

ACR-N

Answer 2

Attenuation-to-Crosstalk
Ratio—Near-End
The ratio between the signal
stren th arriving at the end of a
link Input to the receiver) and
the isturbance caused by the
NEXT coupling from a
disturbing wire pair. ACR-N was
previously called ACR.
TDMM: Page 12-8

Question 3

ATTENUATION

Answer 3

The decrease in magnitude or
the power loss of a signal that
propagates between points,
expressed in decibels (dB) as
the ratio of received signal to
transmitted signal level.
TDMM: Page G-IO

Question 4

CP

Answer 4

Consolidation Point
A connection facility within a
horizontal cabling subsystem for
nterconnection of communication
cables extending from building
pathways into furniture pathways
or modular wall partitions to the
equipment outlet.
TDMM: Page G-31

Question 5

DELAY SKEW

Answer 5

The difference in the
propagation delay between the
fastest and slowest pairs within
the same cable sheath.
TDMM: Page G-36

Question 6

EMI

Answer 6

Electromagnetic Interference
Radiated or conducted
electromaanetic eneray that has
an undesirable effect on
electronic equipment or signal
transmissions.
TDMM: Page G-46

Question 7

FRESNEL REFLECTION

Answer 7

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-57

Question 8

INSERTION LOSS

Answer 8

The signal loss resulting from
the insertion of a component, or
link, or channel, between a
transmitter and receiver (often
referred to as attenuation).
TDMM: Page GÆ5

Question 9

INSERTION LOSS DEVIATION

Answer 9

A measure of the worst-case
difference in the magnitude
between the expected insertion
loss and the actual measured
insertion loss.
TDMM: Page 12-5

Question 10

MUTOA

Answer 10

Multi-User Telecommunications
Outlet Assembly
A grouping in one location of
several telecommunications
outlets/connectors. (TIA)
TDMM: Page G-83

Question 11

NEXT

Answer 11

Near-End Crosstalk
The unwanted signal coupling
between pairs. It is measured at
the end of a cable nearest the
point of transmission.
TDMM: Page G-84

Question 12

NVP

Answer 12

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-86

Question 13

OTDR

Answer 13

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-89

Question 14

PSAACRF

Answer 14

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-97

Question 15

PSAACRN

Answer 15

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-98

Question 16

PSACR

Answer 16

Power Sum Attenuation-to-
Crosstalk Ratio
A ratio in decibels (dB), determined
by subtracting the attenuation from
the ower sum near-end crosstalk
tPSNEXT) loss. PSACR is a
calculated value.
TDMM: Page G-97

Question 17

PSACRF

Answer 17

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-97

Question 18

PSANEXT

Answer 18

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 anotner 4-pair
channel, permanent link, or
component, measured at
the near end.
TDMM: Page G-97

Question 19

PROPAGATION DELAY

Answer 19

The time required for a signal to
travel from one end of the
transmission path
to the other end.
TDMM: Page G-IOO

Question 20

RAYLEIGH SCATTERING

Answer 20

The scattering of light or other
electromagnetic radiation bv
particles much smaller than the
wavelength of the light. It can
occur when light travels through
transparent material (e.o
TDMM: Page G-104

Question 21

RETURN LOSS

Answer 21

A measurement of the reflection
of signal power resulting from
the insertion of a device in a
transmission line (in decibels).
TDMM: Page 12-5

Question 22

SNR

Answer 22

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 codin and is a determining
factor in it error rate (BER).
TDMM: Page G-715

Question 23

TDR

Answer 23

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 lenath of cables
and locate cable faults.
TDMM: Page G-128