Axis Communications 241SA - page 77

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AXIS 241QA/AXIS 241SA - Glossary
NVR (Network Video Recorder) - A dedicated Network
Video Recorder (NVR) can be used to gather data streams
from remote network cameras and video servers and store
them on a hard disk. An NVR can be a standard
networked PC, or a dedicated video recording hard disk
server with its own software application.
OEM (Original Equipment Manufacturer) - This is a
designation for companies that manufacture equipment
that is then marketed and sold to other companies under
their own names.
PAL (Phase Alternating Line) - PAL is an analog color
encoding system used in television systems in Europe and
in many other parts of the world. PAL defines the video
signal using 625 TV lines per frame, at a refresh rate equal
to 25 frames per second. See also NTSC.
PDA (Personal Digital Assistant) - A small handheld
computer, which usually provides at least a calendar, an
organizer and a notepad.
PEM (Privacy Enhanced Mail) - An early standard for
securing electronic mail. The PEM-format is often used
for representing an HTTPS certificate or certificate
request.
Ping - Ping is a basic network program used
diagnostically to check the status of a network host or
device. Ping can be used to see if a particular network
address (IP address or host name) is occupied or not, or if
the host at that address is responding normally. Ping can
be run from e.g. the Windows Command prompt or the
command line in Unix.
Pixel (Picture Element) - A pixel is one of the many tiny
dots that make up a digital image. The color and intensity
of each pixel represents a tiny area of the complete image.
PoE (Power over Ethernet) - Power over Ethernet
provides power to a network device via the same cable as
used for the network connection. This is very useful for
IP-Surveillance and remote monitoring applications in
places where it may be too impractical or expensive to
power the device from a power outlet.
PPP (Point-to-Point Protocol) - A protocol that uses a
serial interface for communication between two network
devices. For example, a PC connected by a phone line to a
server.
PPTP (Point-to-Point Tunneling Protocol) - A protocol
(set of communication rules) that allows corporations to
extend their own corporate network through private
"tunnels" over the public Internet. In this way a
corporation can effectively use a WAN (Wide Area
Network) as a large single LAN (Local Area Network). This
kind of interconnection is known as a virtual private
network (VPN).
Pre/post alarm images - The images from immediately
before and after an alarm. These images are stored in a
buffer for later retrieval.
Progressive scan - Progressive scan, as opposed to
interlaced video, scans the entire picture, line by line
every sixteenth of a second. In other words, captured
images are not split into separate fields as in interlaced
scanning.
Computer monitors do not need interlace to show the
picture on the screen, but instead show them
progressively, on one line at a time in perfect order i.e. 1,
2, 3, 4, 5, 6, 7 etc., so there is virtually no "flickering"
effect. In a surveillance application, this can be critical
when viewing detail within a moving image, such as a
person running. A high-quality monitor is required to get
the best from progressive scan. See also Interlacing.
Protocol - A special set of rules governing how two
entities will communicate. Protocols are found at many
levels of communication, and there are hardware
protocols and software protocols.
Proxy server - In an enterprise that uses the Internet, a
proxy server acts as an intermediary between a
workstation user and the Internet. This provides security,
administrative control, and a caching service. Any proxy
server associated with a gateway server, or part of a
gateway server, effectively separates the enterprise
network from the outside network and the local firewall.
It is the firewall server that protects the enterprise
network from outside intrusion.
PTZ (Pan Tilt Zoom) - A PTZ-enabled camera can be
remotely controlled so as to change the view from the
camera. Panning is the movement of the camera along its
horizontal axis, tilting is the movement of the camera
along its vertical axis, and zooming is the adjustment of
the zoom lens to magnify the view.
P-VOP - See VOP.
Quad view - A Quad view displays images from up to
four cameras on a single screen; where the images from
each camera take up approximately a quarter of the
display area.
Remote monitoring - Network video gives users the
ability to gather information at all key points of an
operation and view it in realtime. This makes the
technology ideal for monitoring equipment, people and
places, both locally and remotely. Application examples
include traffic and production line monitoring, and the
monitoring of multiple store locations.
Resolution - Image resolution is a measure of how much
detail a digital image can hold: the greater the resolution,
the greater the level of detail. Resolution can be specified
as the number of pixel-columns (width) by the number of
pixel-rows (height), e.g. 320x240.
Alternatively, the total number of pixels (usually in
megapixels) in the image can be used. In analog systems
it is also common to use other format designations, such
as CIF, QCIF, 4CIF, etc.