Glossary of Terms

The Nortek Security & Control Family of Brands

Here is a list of terms that will help you understand our products better.

A-B – C – D-G – H-I – M-Q – R-S – T-Z


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

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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 in 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

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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 — Filters 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

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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 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 which do not amplify the signal

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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

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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 RG59 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 (µV), 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

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Tap — A device inserted into a feeder line which 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 (Ultra High 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

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