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
