Axis 206 User Manual page 34

AXIS 206 - Glossary
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MPEG-2 format for encoding analog video signals.
Encoder - See Video encoder.
Ethernet - Ethernet is the most widely installed local area
network technology. An Ethernet LAN typically uses special
grades of twisted pair wires. The most commonly installed
Ethernet systems are 10BASE-T and 100BASE-T10, which
provide transmission speeds up to 10 Mbps and 100 Mbps
respectively.
ETRAX (Ethernet Token Ring AXIS) - The ETRAX chip is
the cornerstone of Axis technology and the 'brain' in nearly
all Axis products. A multipurpose Linux chip with
integrated Ethernet networking and extremely flexible I/O
options.
Factory default settings - These are the settings that
originally applied for a device when it was first delivered
from the factory. If it should become necessary to reset a
device to its factory default settings, this will, for many
devices, completely reset any settings that were changed by
the user.
Firewall - A firewall works as a barrier between networks,
e.g. between a Local Area Network and the Internet. The
firewall ensures that only authorized users are allowed to
access the one network from the other. A firewall can be
software running on a computer, or it can be a standalone
hardware device.
Fixed dome network camera - This type of camera cannot
be remotely controlled as regards movement, but is
mounted in the same type of dome as a controllable
network dome camera. This camera must be positioned
manually to provide the required coverage.
Fixed network camera - This type of camera cannot be
remotely controlled as regards movement. It must be
positioned manually to provide the required coverage.
Fixed iris - See Autoiris.
Focal length - Measured in millimeters, the focal length of a
camera lens determines the width of the horizontal field of
view, which in turn is measured in degrees.
FTP (File Transfer Protocol) - FTP is an application protocol
that uses the TCP/IP protocols, used to exchange files
between computers/devices on networks.
Frame - A frame is a complete video image. In the 2:1
interlaced scanning format of the RS-170 and CCIR formats,
a frame is made up of two separate fields of 262.5 or 312.5
lines interlaced at 60 or 50 Hz to form a complete frame,
which appears at 30 or 25 Hz. In video cameras with a
progressive scan, each frame is scanned line-by-line and
not interlaced; most are also displayed at 30 and 25 Hz.
Frame rate - The frame rate used to describe the frequency
at which a video stream is updated is measured in frames
per second (fps). A higher frame rate is advantageous when
there is movement in the video stream, as it maintains
image quality throughout.
Full-duplex - Transmission of data in two directions
simultaneously. In an audio system this would describe e.g.
a telephone systems. Half-duplex also provides
bi-directional communication, but only in one direction at a
time, as in a walkie-talkie system. See also Simplex.
Gain - Gain is the amplification factor and the extent to
which an analog amplifier boosts the strength of a signal.
Amplification factors are usually expressed in terms of
power. The decibel (dB) is the most common way of
quantifying the gain of an amplifier.
Gateway - A gateway is a point in a network that acts as an
entry point to another network. In a corporate network for
example, a computer server acting as a gateway often also
acts as a proxy server and a firewall server. A gateway is
often associated with both a router, which knows where to
direct a given packet of data that arrives at the gateway,
and a switch, which furnishes the actual path in and out of
the gateway for a given packet.
GIF (Graphics Interchange Format) - GIF is one of the most
common file formats used for images in web pages. There
are two versions of the format, 87a and 89a. Version 89a
supports animations, i.e. a short sequence of images within
a single GIF file. A GIF89a can also be specified for
interlaced presentation.
Half-duplex - See Full-duplex.
HTML (Hypertext Markup Language) - HTML is the set of
"markup" symbols or codes inserted in a file intended for
display in web browser. The markup tells the browser how
to display the page's words and images for the user.
HTTP (Hypertext Transfer Protocol) - HTTP is the set of
rules for exchanging files (text, graphic images, sound,
video, and other multimedia files) on the web. The HTTP
protocol runs on top of the TCP/IP suite of protocols.
HTTPS (Hypertext Transfer Protocol over SSL) - HTTPS is
a protocol used by web browsers and servers to encrypt and
decrypt user page requests and the pages returned by the
server. The encrypted exchange of information is governed
by the use of an HTTPS certificate (issued by a Certificate
Authority), which guarantees the authenticity of the server.
Hub - A (network) hub is used to connect multiple devices
to the network. The hub transmits all data to all devices
connected to it, whereas a switch will only transmit the data
to the device it is specifically intended for.
IEEE 802.11 - A family of standards for wireless LANs. The
802.11a standard supports 1 or 2 Mbit/s transmission on the
5 GHz band. IEEE 802.11b supports data rates up to11
Mbit/s on the 2.4 GHz band, while 802.11g allows up to 54
Mbit/s on the 2.4 GHz band.
Image compression - Image compression minimizes the file
size (in bytes) of an image. Two of the most common
compressed image formats are JPEG and GIF. See also
MPEG and Motion JPEG.
Interlacing - Interlaced video is video captured at 50