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AXIS 262 - Glossary
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.
NAT - Network Address Translation is a standard used to
allow multiple PCs on a private network to share a single,
globally routable IP address.
NTSC - National Television Standards Committee. NTSC is
the standard format used for televisions in most of North
and Central America, and Japan.
NTP - Network Time Protocol. Protocol designed to
synchronize the clocks of computers over a network.
NWAY - A network protocol that automatically
negotiates the highest possible common transmission
speed between two devices.
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 - Simple Mail Transfer Protocol is the protocol used
to send e-mail across the Internet. SMTP authentication is
a way of allowing people outside of a domain to use an
SMTP server when sending e-mail.
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.
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).
