Television Glossary & Links

Bullet Glossary


Listed below are terms used in the broadband, broadcast, and consumer side of the television experience.  The mission of this glossary is to be concise.  Therefore, all definitions are in one sentence consisting of thirty words or less.  This format is meant to satisfy those readers looking for a "quick hit" for their understanding.  Of course, in recognition that many technical concepts cannot begin to be described with this format, a link is provided to a search form for additional research.  The user can highlight and copy the term or keywords in the definition, click the  hyperlinked term, and paste the words into the form to allow a search.


 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

A

Active

  • A powered electronic device that alters in some way the signal presented to it.

Aerial

  • In cable broadband, it is a reference to plant facilities hung on poles.

AFC

  • Automatic Frequency Control

Agile

  • A device capable of user frequency selection as opposed to being fixed in frequency.

AGC

  • Automatic Gain Control

AM

  • Amplitude Modulation

AML

  • Amplitude Modulated Link

Amplifier

  • A device used to increase the strength of the signal supplied to it.

Analog

  • A descriptor for quantities varying continuously rather than in discrete steps.

Anchor

  • In aerial construction, a buried metal structure to which guy wires are tied.

Antenna

  • A device designed to collect or emit electromagnetic energy.

APL

  • Average Picture Level

Array

  • An arrangement of antenna elements or antennas for increasing the strength of desired signals while reducing the strength of undesired signals.

ATSC

ASC

  • Automatic Slope Control

Aspect Ratio

  • Picture width to height (4:3 for NTSC and 16:9 for ATSC)

Attenuation

  • The loss of signal through transmission often expressed in decibels.

Attenuator

  • A device that is used to weaken the strength of the signal supplied to it.

Audio

  • A reference to electronically reproduced sound or the equipment processing it.

Aural Carrier

  • In analog television, the portion of channel radio energy carrying the sound.

B

Back Porch

  • A reference to that part of the video signal immediately following the horizontal sync pulse.

Bandpass Filter

  • A device that passes a range of frequencies while blocking frequencies outside that range.

Bandwidth

  • The useable range of frequencies of a given device or system.

Baseband

  • The originating signal information before it is modulated onto a radio frequency carrier.

Beamwidth

  • The angular width at which an antenna's receive or transmit capability drops to half power.

Beats

  • Undesired sum and difference frequency products created in an electronic device from two or more signals which can interfere with the desired signal.

Blacker-than-Black

  • Below reference black level (sync pulse direction) in a composite video signal.

Black Level

  • The brightness of black (peak) in a video signal (referenced in NTSC as 7.5 IRE).

Blanking

  • That part of the video signal where the amplitude and timing renders retrace as invisible.

Block Converter

  • A device that shifts a group of frequencies to a higher or lower grouping.

Block Tilt

  • Tilt in broadband plant achieved by stepped signal levels of groups of frequencies.

Breezeway

  • That part of the video signal between the sync pulse and the color burst.

Bridger

  • In cable broadband, it is the amplifier that is fed from the trunk and, in turn, feeds the distribution plant.

Broadband

  • In general, a large frequency capacity electronic device; in particular, a closed large capacity interactive electronic distribution system of multiple services to subscribers.

Broadcast

  • An open, limited frequency capacity electronic transmission serving the public.

C

C-Band

  • A satellite delivery system using a 3.7 - 4.2 GHz downlink.

Cable Modem

  • A device used at the subscriber household to receive and transfer data at high speeds.

CARS

  • Community Antenna Relay Service and Community Antenna Relay Station.

CATV

  • Community Antenna Television

Carrier or Carrier Wave

  • An electromagnetic wave that is dynamically altered in order to convey intelligence.

Cascade

  • Two or more amplifiers used in series to perpetuate an electronic signal.

CLI

  • Cumulative Leakage Index

Coaxial Cable

  • A broadband cable with a center conductor, insulating dielectric, and an outer shield.

Color Burst

  • In NTSC, a few cycles of the 3.58MHz color subcarrier imposed on the composite video signal back porch as a reference.

Co-Channel Interference

  • Interference created on a channel by a distant channel on the same frequency.

Combiner

  • A isolating passive device used to combine differing channel outputs into a single output.

Composite Video Signal

  • The complete video signal including blanking, synchronization, and color information (if used).

Converter

  • A frequency changing device of which the most commonly known version is the customer set-top box.

Core Shrink-back

  • When the center conductor of a coaxial cable or the entire cable itself pulls out of a connector due to temperature related contraction, also known a "suckout".

Cross Modulation

  • A type of distortion where modulation from a channel or channels is superimposed onto another channel when they pass through a non-linear circuit.

CRT

  • Cathode Ray Tube

Cycle

  • A complete change in a waveform from zero to a negative peak to zero, then to a positive peak and back to zero.

D

dB

  • Decibel, a unit relating the ratio of two signal levels using a logarithmic scale.

dBm

  • Decibel Milliwatt.

dBmV

  • Decibel Millivolt.

DBS

  • Direct Broadcast Satellite.

dBW

  • Decibel Watt.

Demodulator

  • An electronic device used to remove the intelligence riding a carrier wave so that it may be displayed or processed.

Diplexer

  • In broadband, a device that combines or splits differing frequency carriers.

Dipole

  • A one-half wavelength center fed antenna consisting of two radiating elements.

Direct Pickup

  • Undesired broadcast station ingress from the air and into the cable television system or customer equipment

Directional Coupler

  • A passive device used to divide signals with the "through" port experiencing minimum loss, the "tap" port having a greater specified loss, and a high isolation loss between these ports.

Dish

  • A reference to a parabolic antenna commonly designed for use at microwave frequencies.

Distortion

  • Undesired changes in a signal waveform caused by the inherent nonlinearities of active devices and other processing elements of the transmission system.

Distant Signal

  • A television broadcast signal that is received outside of its Grade B contour.

DLP

  • Digital Light Processing

DOCSIS

Downlink

  • The signal transmission from a satellite to an earth station.

Downstream

  • The signal flow direction when it travels from the headend to the service subscriber in a cable broadband system.

Drop

  • The cable line connecting the subscriber household to the distribution plant of their broadband services supplier.

E

Earth Station

  • The antenna and associated electronic equipment needed for satellite communications.

Effective Height

  • The height of a antenna from ground in terms of its center of radiation rather than its physical location.

ERP

  • Effective Radiated Power

Egress

  • In cable broadband, it is the undesired leakage of signals from the plant into the air.

EIA

  • Electronics Industries Association

Electrical Length

  • In regard to performance, it is the effective length  of an electrical device such as an antenna or transmission line (often expressed in wavelengths) rather than the physical length.

Electromagnetic Spectrum

  • The entire range of frequencies at which energy may be electromagnetically radiated which includes everything from subaudible frequencies to gamma ray frequencies.

Encoder

  • A device used to alter a signal so that it cannot be readily used unless another device (decoder) is authorized to do so.

Encryption

  • The act of applying algorithms or coding to information so that it cannot be used without the proper "keys" to do so.

Equalization

  • The application of frequency response devices to an electronic system to compensate for the  frequency related losses of that system.

Equalizer

  • In cable broadband, a passive device designed with a frequency response tilt opposite of the inherent response tilt in the cable that precedes it. 

F

FDM

  • Frequency Division Multiplexing

Feeder Cables

  • In a cable broadband system, it is the intermediate lines of distribution that carry the signals from the main trunk lines to the subscriber lines.

Field

  • One-half of a complete frame of video with each half being composed of either odd or even scan lines. 

Field Strength

  • Also known as Field Intensity, it is the strength of a radio wave at a given point.

Filter

  • A passive device used to shape, pass,or block the frequency response of the signal fed to it.

Flooding Compound

  • A viscous material placed within a cable to guard against water infiltration.

FM

  • Frequency Modulation

Footcandle

  • A measurement unit of illumination where 1 lumen is equally distributed across 1 square foot.

Footprint

  • The area of earth covered by a satellites directed beam.

Forward Direction

  • In cable broadband, the direction of signal flow from the headend to the subscriber.

Frame

  • A single complete video picture composed of the odd scan line field and the even scan line field interlaced together.

Franchise

  • Legal authorization issued by the local governing body (usually city, but can be county or state) to build and operate a cable television system in that jurisdiction.

Frequency

  • The cycles-per-second count of a given audio or radio wave

Frequency Response

  • The signal amplitude gain/loss across the frequency bandwidth of a given device or transmission system.

Frequency Suckout

  • A sharp signal loss or notch within a device or system's passband.

FSK

  • Frequency Shift Keying

Front Porch

  • The part of the video synchronization signal that follows the picture information and precedes the horizontal sync pulse.

Funny Paper Effect

  • The misregistration seen on video when the chrominance information either leads or lags the luminance information.

G

Gain

  • Usually expressed in decibels, it is the increase in signal strength through an amplifying device when comparing the output value to the input value.

Geostationary

  • A satellite that is in an orbit that allows travel that is synchronized with the earth's rotation, thus creating a constant "stationary" relationship.

Geosyncronous

  • See "Geostationary".

Group Delay

  • The difference in transmission time between frequency elements passing through an electronic device or medium.

Guard Band

  • Radio frequency spectrum left unused between channels in order to avoid interference.

H

Harmonic Distortion

  • Unwanted frequency multiples of the frequency fundamental(s) that are generated due to the nonlinearities of an electronic device.

HDMI

  • High Definition Multimedia Interface

HDTV

  • High Definition Television

Headend

  • The central electronics facility of a cable broadband system where all signal sources are generated, gathered, processed, combined, and fed into the trunking/distribution system.

Heterodyne

  • To electronically mix two frequencies together in a nonlinear device in order to produce two new frequencies equal to the sum and difference of the originating frequencies.

High Band

  • The band of frequencies covering 174MHz to 216MHz where channels 7 to 13 reside.

High Pass Filter

  • A filter that attenuates all frequencies below a designated cutoff point and passes all frequencies above that point

Home Theater

  •  A recreation of the cinema experience in the home that can range from simple multichannel sound and large screen enhancements to the construction of theater staging and seating.

HRC

  • Harmonically Related Carriers

Hub

  •  A signal processing facility located between the headend and the signal distribution system in order to provide customized regional services.

Hue

  • The dominant optical wavelength that causes visual perception to distinguish a particular color apart from others.

Hum

  •  In audio, it is a low pitched interference tone often picked up from AC power sources, while in cable broadband it is often a reference to visual Hum Modulation.

Hum Modulation

  • The undesired modulation of the visual carrier by power line frequencies and harmonics (or other low frequency disturbances) sometimes visible as bars rolling through the picture.

Hz

  • Hertz, a measure of frequency known formerly as "cps" or "cycles-per-second" but renamed in honor of Heinrich Rudolph Hertz who furthered the understanding of electromagnetic waves.

I

IF

  • Intermediate Frequency

Impedance

  • The total resistive and reactive opposition to the flow of an alternating current signal at a given frequency.

Impulse Noise

  • Short duration transient disturbances.

Inductor

  • A coiled conductor designed to oppose changes in current by virtue of its concentrated magnetic field.

Infrared

  • The section of electromagnetic spectrum just below visible light.

Ingress

  • The undesired influx of interference into a cable broadband system from sources outside of the system.

IRC

  • Incrementally Related Carriers

Isolation

  • The attribute of a device that minimizes signal transfer from one point to an inappropriate point.

J

Jitter

  • An unstable picture usually caused by disturbances to synchronization.

Jumper Cable

  • In cable broadband, it is a short length of coaxial cable used to connect close proximity devices such as a converter box and the customer television.

K

Ku Band

  • The band of microwave frequencies extending from 12 to 18GHz (in North America, the reference commonly refers to the 11.7 to 12.2GHZ satellite downlink portion).

L

LASER

  • Light Amplification by Stimulated Emission of Radiation

Lasher

  • A machine used in aerial construction to tie the communications lines to the support strand by spin-wrapping wire around the cable bundle.

LCD

  • Liquid Crystal Display

LCoS

  • Liquid Crystal on Silicon

Leakage

  • Undesired signal emissions from a cable broadband system (often from cable cracks or poor connections) into the air.

LED

  • Light Emitting Diode

Line Extender

  • An amplifier used in the distribution system of cable broadband to extend the reach of the signal.

Line-of-Sight

  • An unobstructed path through open space intended for transmit/receive stations such as point-to-point microwave, satellite-to-earth transmissions, and optical laser links.

LNA

  • Low Noise Amplifier

LNB

  • Low Noise Block Converter

LNC

  • Low Noise Converter

Local Origination

  • Programming produced and telecast from the local cable broadband provider.

Local Oscillator

  • The oscillator in superheterodyned equipment that generates the proper frequency signal needed to mix with the received signal to produce the desired intermediate frequency.

Local Signals

  • Television broadcast signals received within their respective Grade B contours.

Log Periodic Antenna

  • A directional antenna with the radiating elements and spacing arranged in logarithmically increasing dimensions in order to provide wideband reception or transmission.

Low Band

  • The band of frequencies covering 54MHz to 88MHz where channels 2 to 6 reside.

Low Pass Filter

  • A filter that attenuates all frequencies above a designated cutoff point and passes all frequencies below that point

Lumen

  • The unit of light flux from a point source of one candle through a unit solid angle.

Luminance Signal

  • The part of the television signal that carries the brightness information and can produce a complete monochromatic picture.

M

Makeready

  • The process in cable broadband where the readiness of underground and poleline facilities are ensured prior to construction.

MATV

  • Master Antenna Television System

MDS

  • Multipoint Distribution System

MCR

  • Master Control Room

Messenger

  • Refers to either the supporting steel strand to which hardline coaxial cable may be lashed or the supporting steel wire embedded in the jacket of aerial coaxial drop cable.

Microwave

  •  A reference to those radio waves with a frequency above 1000MHz.

Mid Band

  • The band of frequencies covering 120MHz to 174MHz where cable channels A to I reside.

Midspan

  •  A point on the strand and coaxial distribution cables located between two utility poles.

MMDS

  • Multichannel Multipoint Distribution Service

Modulate

  • To alter a constant carrier wave's amplitude, frequency or phase by impressing a varying intelligence wave onto it.

Modulation

  • The electronic process used to impress intelligence onto a carrier wave for transportation to a distant recovery location.

Monitor

  • A term usually applied to a television, a speaker, or other studio equipment used in observing the quality of signal and can also apply to the act of observance itself.

MTS

  • Multichannel Television Sound

N

NAB

  • National Association of Broadcasters

NCTA

  • National Cable Television Association

Noise

  •  Random electron movement in an electronic curcuit that influences the desired signal passing in that circuit.

Noise Figure

  •  The expected amount of noise in decibels added by a given electronic signal processing curcuit.

Noise Temperature

  •  A noise contribution rating derived by positing the temperature of a resistor connected to an ideal amplifier compared to the actual amplifier were it connected to a resistor at 0K.

Notch Filter

  •  A filter designed to pass all frequencies except for that at which it is tuned to attenuate.

NTC-7

  •  Network Transmission Committee guidelines for the placement of test signals in the vertical interval of an NTSC television signal for testing transmission performance.

NTSC

  • National Television System Committee

O

Off-air

  •  Used interchangeably with the term "off-the-air", it denotes signal reception taken off an antenna after passing through the air.

Operating Power

  •  From the viewpoint of a transmitting antenna, it is the actual power supplied to it.

Optical Fiber

  •  A glass or plastic fiber designed to propagate light for the purpose of information transmittal.

Oscilloscope

  •  An electronic testing device designed to graphically display changes in voltage with respect to the passage of time.

P

Parabolic Dish Antenna

  •  

Passband

  •  

Passive

  •  

PPV

  • Pay-Per-View

PCM

  • Pulse Code Modulation

Peak Power

  •  

Peak-to-Peak

  •  

PLL

  • Phase Lock Loop

Phosphorescence

  •  

Pilot Carrier

  •  

Pixel

  •  

Polarity

  •  

Pole Attachment

  •  

Preamplifier

  •  

Pressure Tap

  •  

Propagation

  •  

PSA

  • Public Service Announcement

Public Access Channel

  •  

Q

QAM

  • Quadrature Amplitude Modulation

R

Radiator

  •  

Radio Frequency

  •  

Random Noise

  •  

Raster

  •  

Rectifier

  •  

Reference Signals

  •  

Resolution

  •  

Return Loss

  •  

Reverse Direction

  •  

Ring Network

  •  

RMS

  • Root Mean Square

Roll-off

  •  

S

SAP

  • Secondary Audio Program

Satellite

  •  

SAW filter

  • Surface Acoustic Wave filter

SBE

  • Society of Broadcast Engineers

SCA

  • Subsidiary Communications Authority

Scan Line

  •  

Scramble

  •  

SCTE

  • Society of Cable and Telecommunications Engineers

Second Harmonic

  •  

Second Order Beat

  •  

Sheath Current

  •  

Shield

  •  

Shrink Tubing

  •  

Sidebands

  •  

Signal Generator

  •  

Signal Leakage

  •  

Signal Level

  •  

Signal-to-Noise Ratio

  •  

Sine Square Pulse

  •  

Single Channel Antenna

  •  

SLM

  • Signal Level Meter

Slope

  •  

SMATV

  • Satellite Master Antenna Television

SMPTE

  • Society of Motion Picture and Television Engineers

Span

  •  

Span Clamp

  •  

Spectrum Analyzer

  •  

Splitter

  •  

Spurious Signals

  •  

SRL

  • Structural Return Loss

Stacked Array

  •  

Standy Power Supply

  •  

Star Network

  •  

STL

  • Studio-to-Transmitter

Strand

  •  

Stratosphere

  •  

Strip Amplifier

  •  

Studio

  •  

Sub Band

  •  

Subcarrier

  •  

Subscriber Terminal

  •  

STV

  • Subscription Television

SCA

  • Subsidiary Communications Authority

Subsplit

  •  

Super Band

  •  

Superheterodyne

  •  

Supertrunk

  •  

Sweep Generator

  •  

Sync

  •  

T

Tap

  •  

TASO

  •  
  • Television Allocation Study Organization

TBC

  • Time Base Corrector

Telecommunications

  •  

Teleconference

  •  

Television

  •  

Terminal Isolation

  •  

Terminator

  •  

Thermal Equalizer

  •  

Third Harmonic

  •  

Third Order Beat

  •  

Tilt

  •  

TDM

  • Time Division Multiplexing

TDR

  • Time Domain Reflectometer

Trace

  •  

Translator

  •  

Transponder

  •  

Trap

  •  

Traveling-wave Tube

  •  

Triple Beat

  •  

Trophospheric Scatter