User`s manual

66
AXIS 213 - Glossary of Terms
device, to allow it to be identified and found on the
network. The 32-bit IP address is made up of four
groups (or quads) of decimal digits separated by
periods. An example of an IP address is: 192.168.0.1
ISMA - Internet Streaming Media Alliance
JPEG - A standard image format, used widely for
photographs. Also known as JPG.
LAN - A local area network (LAN) is a group of
computers and associated devices that typically share
common resources within a limited geographical area.
Linux - A popular operating system, which is “open
source” and practically free of charge.
Lux - A standard unit for the measurement of light,
where 1 Lux equals the light emitted from a single
candle at a distance of one meter.
Mbit/s - Megabits per second. A unit for measuring
speeds in networks. A LAN might run at 10 or 100
Mbit/s.
MPEG-4 - A standard video format, used for low
bandwidth video streams.
Multicast - The same information is sent only once
and only to the intended recipients.
NTSC - National Television Standards Committee.
NTSC is the standard format used for televisions in
most of North and Central America, and Japan.
PAL - Phase Altering Line. PAL is the standard format
used for televisions in most of the world (other than
the US, Canada, and Japan).
PCM - Pulse Code Modulation. Analog signal
converted directly to a digital.
Ping - A small utility used for sending data packets to
network resources to check that they are working and
that the network is intact.
Pre/post alarm image - The images from immediately
before and after an alarm.
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.
Router - A device that determines the next network
point to which a packet should be forwarded on its
way to its final destination. A router is often included
as part of a network switch (see below).
RTP- Real-Time Transfer Protocol. A transfer protocol
designed for delivery of live contents, e.g. MPEG-4.
Simplex - In simplex operation, a network cable or
communications channel can only send information
in one direction.
SMTP - A common e-mail protocol.
Subnet Mask - An IP address consists of two
components: the network address and the host
address. “Subnetting’ enables a network administrator
to further divide the host part of the address into two
or more subnets. The subnet mask identifies the subnet
to which an IP address belongs.
Switch - Whilst a simple hub transmits all data to all
devices connected to it, a switch only transmits the
data to the device it is specifically intended for.
TCP/IP - Transmission Control Protocol/Internet
Protocol. A suite of network protocols that determine
how data is transmitted. TCP/IP is used on many
networks, including the Internet. TCP keeps track of
the individual packets of information and IP contains
the rules for how the packets are actually sent and
received.
UPnP - Universal Plug and Play. An “address" on the
network. UPnP is an architecture for pervasive
peer-to-peer network connectivity of intelligent
appliances, wireless devices, and PCs of all form
factors.
URL - Uniform Resource Locator. An “address" on the
network.
Varifocal - A varifocal lens provides a wide range of
focal lengths, as opposed to a lens with a fixed focal
length, which only provides one.
WAN - Wide-Area-Network. Similar to a LAN, but on
a larger geographical scale.
Web server - A program on a computer (server)
providing the resources (e.g. web pages) requested by
the user (client).