Sun Surveillance, wireless solar powered video surveillance, glossary p

The Glossary

An all inclusive glossary of security lingo is provided for your convenience. This list
will undoubtedly be helpful when delving in to the realm of security.

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 photo sensor.
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 photo sensor 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.
Plumb icon - Thermionic vacuum tube developed by Philips, using a lead oxide photoconductive layer. It
represented the ultimate imaging device until the introduction of CCD chips.
Polarizing filter An optical filter that transmits light in only one direction (perpendicular to the light path), out
of 360° possible. The effect is such that it can eliminate some unwanted bright areas or reflections, such
as when looking through a glass window. In photography, polarizing filters are used very often to darken a
blue sky.
POTS - Plain old telephone service. The telephone service in common use throughout the world today.
Also known as PSTN.
P-picture - Prediction-coded picture. An MPEG term to describe a picture that is coded using motion-
compensated prediction from the past reference picture.
Preset positioning A function of a pan and tilt unit, including the zoom lens, where a number of certain
viewing positions can be stored in the system’s memory (usually this is in the PTZ site driver) and recalled
when required, either upon an alarm trigger, programmed or manual recall.
Primary colors - A small group of colors that, when combined, can produce a broad spectrum of other
colors. In television, red, green and blue are the primary colors from which all other colors in the picture are
derived.
Principal point - One of the two points that each lens has along the optical axis. The principal point closer
to the imaging device (CCD chip in our case) is used as a reference point when measuring the focal length
of a lens.
PROM - Programmable read only memory. A ROM that can be programmed by the equipment
manufacturer (rather than the PROM manufacturer).
Protocol - A specific set of rules, procedures or conventions relating to format and timing of data
transmission between two devices. A standard procedure that two data devices must accept and use to be
able to understand each other. The protocols for data communications cover such things as framing, error
handling, transparency and line control.
PSTN - Public switched telephone network. Usually refers to the plain old telephone service, also known as
POTS.
PTZ camera - Pan, tilt and zoom camera.
PTZ site driver (or receiver or decoder) - An electronic device, usually a part of a video matrix switcher,
which receives digital, encoded control signals in order to operate pan, tilt, zoom and focus functions.
Pulse - A current or voltage that changes abruptly from one value to another and back to the original value
in a finite length of time. Used to describe one particular variation in a series of wave motions.

Courtesy of CCTV Labs and CCTV focus magazine

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