Datasheet

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AXIS 292 - Glossary of Terms
user with whatever privileges you may have been granted for specific
applications and data residing on that computer.
TVL (TV Lines) - A method of defining resolutions in analog video.
UDP (User Datagram Protocol) - UDP is a communications protocol that
offers lim
ited service for exchanging data in a network that uses the
Internet Protocol (IP). UDP is an alternative to the Transmission Control
Protocol (TCP). The advantage of UDP is that it is not required to deliver
all data and may drop network packets when there is e.g. network
congestion. This is suitable for live video, as there is no point in
re-transmitting old information that will not be displayed anyway.
Unicast - Communication between a single sender and a single receiver
over a network. A new
connection is established for each new user.
URL (Uniform Resource Locator) - An "address" on the network.
USB - (Universal Serial Bus) A plug-and-play interface between a
computer and perip
heral devices, e.g. scanners, printers, etc.
Varifocal lens - A varifocal lens provides a wide range of focal lengths,
as op
posed to a lens with a fixed focal length, which only provides one.
VPN (Virtual Private Network) - This creates a secure "tunnel" between
the
points within the VPN. Only devices with the correct "key" will be
able to work within the VPN. The VPN network can be within a company
LAN (Local Area Network), but different sites can also be connected over
the Internet in a secure way. One common use for VPN is for connecting a
remote computer to the corporate network, via e.g. a direct phone line or
via the Internet.
VOP (Video Object Plane) - A VOP is an image frame in an MPEG-4
video stream.
There are several types of VOP:
- An I-VOP is complete image frame.
- A P-VOP codes the differences between images, as long as it is more
eff
icient to do so. Otherwise it codes the whole image, which may also be
a completely new image.
WAN (Wide-Area-Network) - Similar to a LAN, but on a larger
geogra
phical scale.
W-LAN (Wireless LAN) - A wireless LAN is a wireless local area network
that uses
radio waves as its carrier: where the network connections for
end-users are wireless. The main network structure usually uses cables.
Web server - A Web server is a program, which allows Web browsers to
re
trieve files from computers connected to the Internet. The Web server
listens for requests from Web browsers and upon receiving a request for a
file sends it back to the browser.
The primary function of a Web server is to serve pages to other remote
computers;
consequently, it needs to be installed on a computer that is
permanently connected to the Internet. It also controls access to the
server whilst monitoring and logging server access statistics.
WEP (Wireless Equivalent Privacy) - A wireless security protocol,
s
pecified in the IEEE 802.11 standard, which is designed to provide a
wireless local area network (WLAN) with a level of security and privacy
comparable to that usually expected of a wired LAN. Security is at two
different levels; 40-bit and 128-bit encryption. The higher the bit number,
the more secure the encryption.
WINS (Windows Internet Naming Service) - Part of the Microsoft
Windows
NT Server, WINS manages the association of workstation names
and locations with IP addresses, without the user or administrator having
to be involved in each configuration change.
WPA-PSK (Wi-Fi Protected Access - Pre-Shared Key)
- This wireless
encryption method uses a pre-shared key (PSK) for key management.
Keys can usually be entered as manual hex values, as hexadecimal
characters, or as a Passphrase. WPA-PSK provides a greater degree of
security than WEP.
Zoom lens - A zoom lens can be moved (zoomed) to enlarge the view of
an
object to show more detail.