Glossary Of Terms - AV, Audio Visual, TV
Aerial / Antenna - An electrical conductor that transmits / receives electromagnetic waves, otherwise known as radio waves.
Amplifier - Boosts the strength of the signal to different locations.
Analogue - Historical mode of transmission using standard wave bands for transmission of TV services.
Attenuation - Describes reduction in power of the signal received at the transmission and reception points.
Bandwidth - The amount of information carried on a communication channel. Bandwidth corresponds to the difference between the lowest and the highest frequency signal, which can be carried by the channel.
Cable Loss - Measured in decibels this describes the amount of signal loss between two points on a length of cable.
Coax / Coaxial - Cable Used to transfer the signal received from the transmitter to the antenna, usually 75Ohms.
Coverage - Used to describe the areas that are currently covered by Digital/Analogue television signals.
dB / Decibels - A way of measuring voltage, power, gain, loss or frequency between input and output devices.
D-CAB Digital cable Dielectrics - Various insulating materials used in coaxial cable to insulate the centre conductor.
Directional Antenna - An antenna that can receive or send signals more effectively from 360 degrees.
D-SAT - Digital Satellite
DTT - Digital Terrestrial Television
DTV - Digital Television
Elements - Parts of the aerial that cross the boom. Aerials vary in the amount of elements they contain. The elements are the conductive part of the aerial.
F-Connector - Attached to the drop cable that plugs into the set-top box, cable ready TV or Satellite
Frequency - This is the number of cycles per second of a wave signal.
Frequency - Bandwidth This is the range at which signal is received by the antenna dependant on the antennas performance.
HDTV / High Definition Television - Method of transmission producing higher quality pictures.
Hertz (Hz) - A unit of frequency equal to one cycle per second.
Impedance - A combination of resistance and reactance, measured in Ohms, usually used to describe the characteristics in antennas and coax cable.
IRS Integrated Receiver System – this is a shared reception often used in flats, hotels etc that allows for television, radio and other services signal to be shared on a distribution system.
Low Noise Amplifier / LNA - A low noise signal booster that amplifies weak signals.
Low Pass Filter / LPF - Allows the signal to pass either way by allowing low frequencies to pass but blocks out high frequencies.
Modulator - A device that takes the video and audio signal that are separated by the receiver and combines them into an RF signal that can be received by a TV set without scart input.
Ohm - This is the standard unit of measurement for resistance, reactance and impedance.
Omni - An antenna that provides 360-degree transmission pattern, used when coverage in all directions is required.
Repeater - Repeats the signal from one cable to another whilst restoring signal timing and waveforms to maintain the quality of image and sound
Return Loss - Explains the power that is reflected by the antenna to the power that is then fed into the antenna from the transmission line.
RF - Radio Frequency
TETRA / Terrestrial Trunked Radio - Used for larger mobile radio communication networks such as the emergency services. This can cause interference to TV signals for those areas that are close to a TETRA base station. TETRA filtered amplifiers are available to resolve this issue.
UHF/Ultra High Frequency - Channels above channel 13 (470MHz to 806MHz)
VHF / Very High Frequency - Channels 2 – 13 (54-88MHz and 174-216MHz)
Wavelength - The distance a wave travels to complete one cycle is known as the wavelength of the signal.
Yagi - A directional gain antenna using one or more parasitic elements, named after one of the Japanese inventors.
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