User`s manual

39
AXIS 206 - Glossary
Time-lapse recorder - This type of video recorder is
commonly used in the security industry and has the ability
to record up to one week of video on a single tape. The most
commonly used timing is the 24-hour mode. Having to
change tapes only once a day and retaining large amounts
of information are perceived as key advantages in using this
particular mode of recording.
TVL (TV Lines) - A method of defining resolutions in
analog video.
UDP (User Datagram Protocol) - UDP is a communications
protocol that offers limited 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. See also Multicast.
UPnP
TM
- A set of computer network protocols that allows
the automatic peer-to-peer detection of devices on the
network. UPnP is promoted by the UPnP Forum.
URL (Uniform Resource Locator) - An "address" on the
network.
USB (Universal Serial Bus) - A plug-and-play interface
between a computer and peripheral devices (scanners,
printers etc)
Varifocal lens - A lens that provides a wide range of focal
lengths, as opposed to a lens with a fixed focal length,
which only provides one.
Video camera - See Network camera and CCTV video
camera.
Video decoder - A network video decoder converts digital
video and audio streams back into analog signals, which
can then be displayed on standard TV sets, analog monitors
and video switches.
Video encoder (video server) - A video encoder/server
digitizes analog video signals and sends digital images
directly over an IP network, such as a LAN, intranet or the
Internet. In effect, it turns an analog video system into a
network video system and enables users to view live images
using a web browser or application software on any local or
remote computer on a network.
Video management software - Video management software
supplies the means for monitoring, analyzing and recording
network video. In its simplest form, it offers live viewing,
storage and retrieval of video sequences. Advanced
applications may also provide support for recording of live
video from multiple devices, different recording modes,
search functions, remote access via a web browser, control
of PTZ devices, etc.
VMD (Video Motion Detection) - Video Motion detection
defines activity (motion) in a monitored scene by analyzing
image data and differences in series of images. This
detection can, for example, be used to trigger an alarm
event in a network camera and start the upload of images
from the camera.
Video switcher - An analog video switcher sequentially
displays full screen images, from one camera after another,
typically at 3-5 seconds intervals. Other camera sources are
not recorded while the image source from one camera is
displayed on screen.
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.
WAN (Wide-Area-Network) - Similar to a LAN, but on a
larger geographical 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 camera (Webcam) - A camera that requires a constant
connection (via e.g. USB) to a PC for its operation. See also
Network camera.
Web server - A program that allows web browsers to
retrieve files from computers connected to the Internet. The
Web server listens for requests from 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.
WEP (Wireless Equivalent Privacy) - A wireless security
protocol, specified 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.