CCTV Glossary
Cascadia Video Products LLC
27 / 43
P
PAL.- Phase alternating line. Describes the color phase change in a PAL color signal. PAL is a
European color TV system featuring 625 lines per frame, 50 fields per second and a 4.43361875-
MHz sub-carrier. Used mainly in Europe, China, Malaysia, Australia, New Zealand, the Middle East
and parts of Africa. PAL-M is a Brazilian color TV system with phase alternation by line, but using
525 lines per frame, 60 fields per second and a 3.57561149 MHz sub-carrier.
Pan and tilt head (P/T head). - A motorized unit permitting vertical and horizontal positioning of a
camera and lens combination. Usually 24 V AC motors are used in such P/T heads, but also 110
VAC, i.e., 240 VAC units can be ordered.
Pan unit. - A motorized unit permitting horizontal positioning of a camera.
Peak-to-peak (pp). - The amplitude (voltage) difference between the most positive and the most
negative excursions (peaks) of an electrical signal.
Pedestal.- In the video waveform, the signal level corresponding to black. Also called setup.
Phot.- A photometric light unit for very strong illumination levels. One phot is equal to 10,000
luxes.
Photodiode.- A type of semiconductor device in which a PN junction diode acts as a photosensor.
Photo-effect.- Also known as photoelectric-effect. This refers to a phenomenon of ejection of
electrons from a metal whose surface is exposed to light.
Photon.- A representative of the quantum nature of light. It is considered as the smallest unit of
light.
Photopic vision. - The range of light intensities, from 105 lux down to nearly 10–2 lux, detectable
by the human eye.
Pinhole lens. - A fixed focal length lens, for viewing through a very small aperture, used in discrete
surveillance situations. The lens normally has no focusing control but offers a choice of iris
functions.
Phase locked loop (PLL). A circuit containing an oscillator whose output phase or frequency locks
onto and tracks the phase or frequency of a reference input signal. To produce the locked condition,
the circuit detects any phase difference between the two signals and generates a correction
voltage that is applied to the oscillator to adjust its phase or frequency.
Photo multiplier. - A highly light-sensitive device. Advantages are its fast response, good signal-
to-noise ratio and wide dynamic range. Disadvantages are fragility (vacuum tube), high voltage and
sensitivity to interference.
Pixel or picture element. - Derived from picture element. Usually refers to the CCD chip unit
picture cell. It consists of a photosensor plus its associated control gates.
The smallest visual unit that is handled in a raster file, generally a single cell in a grid of numbers
describing an image.
(8 paginas)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comentarios a estos manuales