Specifications

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76 Glossary Of Terms
Adjacent Channels: Two television channels
having video carriers 6 MHz apart, or two FM
channels having carriers occupying neighboring
channel allocations
Amplifier: A device used to increase the power
and voltage level of a signal
Attenuator: A passive device used to reduce
signal strength
Baseband: A data signal that has not been
modulated onto a carrier (e.g., Hi-Fi Audio,
NTSC Video, or RS-232 Data)
BID: Bi-directional, as in systems used with
CATV services using pay-per-view or cable
modems; BID is not for use with off-air antennas
Cable Back-Feed: Signals from an inserted
modulated channel that travel back into the
cable source. Using a modulator on a cable
service provider’s system (CATV or MATV)
requires a mixing amplifier or filter (NF-469) to
prevent the signal from back-feeding into the
cable or antenna system.
Category Rated: Twisted pair communications
circuits are rated by category, specifications for
which are covered under EIA/TIA 568; the higher
the category number, the higher the information
capacity of the circuit
CATV (Community Antenna Television): An RF
distribution system that distributes television
broadcast programs, original programs,
premium programming, and other services
using a network of coaxial cable
Channel: In television, a portion of the RF
spectrum, 6 MHz wide, that carries the audio and
video carriers of the television signal
CO (Central Office): A reference to the local
telephone exchange carrier
Coaxial Cable: A concentric cable consisting of
a center conductor, a dielectric, and a shield;
coax used for most MATV and CATV work has a
characteristic impedance of 75 ohms
Composite Video Signal: The composite video
signal including the picture (luminance) signal,
the blanking and sync pulses, and the color
(chrominance)
Cross Connect: The physical connection
between patch panels or punch-down blocks
that facilitates connections from systems and
feeds to drops
Crosstalk: The unwanted introduction of signals
from one channel to another
Decibel: Abbreviation dB; a logarithmic function
used to simplify MATV calculations; decibels can
be added or subtracted; 0 dB is the standard
reference level for all MATV calculations
dBmV: An absolute signal level where 0 dBmV is
equal to 1000 μV across 75 ohms
Egress: A condition often called “signal leakage”
in which signals carried by the distribution
system radiate into the air
Filter: Fibers are used to block out undesired
frequencies; there are two types of filters—band
pass and rejection; a band pass filter permits
only the desired range to pass through, while the
rejection filter attenuates an undesired range of
frequencies
Gain: A measure of amplification of a device,
usually expressed in dB at the highest frequency
of operation
Ghosting: A signal interference condition
producing positive or negative pictures
displaced in time from the desired picture,
caused by multi-path signal reception; ghost
pictures also result from cable ringing
HDTV (High-Definition Television): A high-
resolution, wide-screen common picture
format and transmission standard for bringing
broadcast television to the home
Head End: The equipment located at the start of
a CATV system; the place where the signals are
processed and combined prior to distribution
HHR: A high-head-room amplifier used in high-
performance off-air antennas or non-bi-
directional CATV systems
Ingress: A condition where an unwanted RF
signal leaks into a distribution system
Insertion Loss: Also called “feed through loss”;
this is the loss that occurs as signals pass
through a passive device; insertion loss occurs
in all devices that do not amplify the signal
MATV (Master Antenna Television System):
A distribution system that is usually contained
within a single building and receives its signals
from an antenna or CATV system
Modulation: Placing information, audio/video,
onto a higher frequency carrier by means of
amplitude, frequency, or phase adjustment
Off-Air: Any channel that can be received by a
conventional antenna system, including VHF and
UHF broadcasts
Patch Cords: The cords interconnecting
terminations at the central distribution panel;
typically these cords are terminated with
modular plugs
RF (Radio Frequency): Generally refers to data
modulated over a high-frequency carrier for
wireless transmission
RG-6 Cable: A coaxial cable used for broadband
video applications; RG-6 has an 18-gauge
center conductor, allowing a higher bandwidth
than the RG-59 cable, which has a smaller 20-
gauge center conductor; RG-6 uses standard
“F” connectors for video equipment connections
Signal Strength: The intensity of an RF signal
measured in volts (V), millivolts (mV), microvolts
(mV), or dBmV
Signal-to-Noise Ratio (S/N): The ratio of desired
signal level to the undesired noise level
expressed in dB
Snow: A large quantity of random noise in a
television picture that results from a poor CON
(earner-to-noise) ratio
TAP: A device inserted into a feeder line that
allows a specific amount of signal to be removed
from the feeder line and isolates the TAP port
from the main through line
Terminator: A resistive device that matches a
cable or the unused output of an active or
passive system component to its characteristic
impedance; proper termination is required to
prevent unused portions from causing
reflections back down to the line
Tilt: A linearized change in the frequency
response of the CATV system, caused primarily
by the frequency-dependent cable loss; tilt is
quantified by comparing the difference between
the level of the highest channel’s video carrier
and that of the lowest channel
UHF (Ultrahigh Frequency): Off-air television
channels 14 to 83
UTP (Unshielded Twisted Pair): Twisted pair
cable without either individual or overall
shielding
VHF (Very High Frequency): Off-air television
channels 2 to 13
100BASE-T: 100 Mbps 802.3/Ethernet over
standard unshielded twisted pair cable
specification; 100BASE-T supports network
configurations over twisted pair transmission
systems up to 100 meters in length without
the use of a repeater