CCTV Glossary
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F
FCC - Federal Communications Commission (US).
FFT - Fast Fourier Transformation.
Fiber optics - A technology designed to transmit signals in the form of pulses of light. Fiber optic
cable is noted for its properties of electrical isolation and resistance to electrostatic and
electromagnetic interference.
Field - Refers to one-half of the TV frame that is composed of either all odd or even lines. In
CCIR systems each field is composed of 625/2 = 312.5 lines, in EIA systems 525/2 = 262.5 lines.
There are 50 fields/second in CCIR/PAL, and 60 in the EIA/NTSC TV system.
Film recorder - A device for converting digital data into film output. Continuous tone recorders
produce color photographs as transparencies, prints or negatives.
Fixed focal length lens - A lens with a predetermined fixed focal length, a focusing control and a
choice of iris functions.
Flash memory - Nonvolatile, digital storage. Flash memory has slower access than SRAM or
DRAM.
Flicker - An annoying picture distortion, mainly related to vertical syncs and video fields display.
Some flicker normally exists due to interlacing; more apparent in 50 Hz systems (PAL). Flicker
shows also when static images are displayed on the screen such as computer generated text
transferred to video. Poor digital image treatment, found in low-quality system converters (going
from PAL to NTSC and vice versa), creates an annoying flicker on the screen. There are several
electronic methods to minimize flicker.
F-number - In lenses with adjustable irises, the maximum iris opening is expressed as a ratio
(focal length of the lens)/(maximum diameter of aperture). This maximum iris will be engraved on
the front ring of the lens.
Focal length - The distance between the optical center of a lens and the principal convergent
focus point.
Focusing control - A means of adjusting the lens to allow objects at various distances from the
camera to be sharply defined.
Foot-candela - An illumination light unit used mostly in American CCTV terminology. It equals ten
times (more precisely, 9.29) of the illumination value in luxes.
Fourier Transformation - Mathematical transformation of time domain functions into frequency
domain.
Frame - (See also Field). Refers to a composition of lines that make one TV frame. In
CCIR/PAL TV system one frame is composed of 625 lines, while in EIA/NTSC TV system of 525
lines. There are 25 frames/second in the CCIR/PAL and 30 in the EIA/NTSC TV system.
Frame store - An electronic device that digitizes a TV frame (or TV field) of a video signal and
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