Ericsson MX8400, Reference Manual

Page: 125 / 226

Glossary
UART Universal Asynchronous Receiver Transmitter: A device providing a
serial interface for transmitting and receiving data.
UDP User Datagram Protocol. A protocol above the IP layer that provides
port multiplexing in addition. In essence, you can transmit IP data
packets to several receiving processes in the same unit/device.
Unicast Point-to-point connection, i.e. the "opposite" of multicast which is
one to many (or many to many). In this mode, a transmit unit sends
video data direct to a unique destination address.
Upconvert The process by which the frequency of a broadcast transport stream
is shifted to a higher frequency range.
Uplink The part of the communications satellite circuit that extends from the
Earth to the satellite.
UPS Uninterruptable Power Supply: A method of supplying backup power
when the electrical power fails or drops to an unacceptable voltage
level. Small UPS systems provide battery power for a few minutes;
enough to power down the computer in an orderly manner. This is
particularly important where write back cache is used. Write back
cache is where modified data intended for the disk is temporarily
stored in RAM and can be lost in the event of a power failure.
Sophisticated systems are tied to electrical generators that can
provide power for days. UPS systems typically provide surge
suppression and may provide voltage regulation.
UTC Universal Time Coordinate: An internationally agreed basis for
timekeeping introduced in 1972 and based on international atomic
time (corresponds to Greenwich Mean Time or GMT).
VITC Vertical Interval Time Code.
VITS Vertical Interval Test Signal: See: ITS.
VLAN Virtual LAN, a network of units that behave as if they are connected
to the same wire even though they may actually be physically
located on different segments of a LAN.
VPS Video Programming System: A German precursor to PDC
WSS Wide Screen Switching: Data used in wide-screen analogue
services, which enables a receiver to select the appropriate picture
display mode.
WST World System Teletext: System B Teletext. Used in 625 line / 50 Hz
television systems
(ITU-R 653).
XILINX A type of programmable Integrated Circuit.
XLR Audio connector featuring three leads, two for signal and one for
GND.
XML eXtensible Markup Language. A very common self-describing text-
based data format. Used for many purposes: Meta-data,
configuration files, documents, etc. The readability of the format has
made it very popular and is now the fundament for many types of
WEB services.
2/1553-FGC 101 1014 Uen B A-19