User manual

Glossary
98-140012-A 78
R
RF Radio Frequency. Electromagnetic wave frequencies between about 3 kilohertz and about
300 gigahertz including the frequencies used for communications signals (radio,
television, cell-phone and satellite transmissions) or radar signals.
S
SIM Subscriber Identity Module. The SIM provides secure storing of the key identifying a
mobile phone service subscriber but also subscription information, preferences and
storage of text messages.
SIP Session Initiation Protocol. An application-layer control (signaling) protocol for creating,
modifying, and terminating sessions with one or more participants. Used e.g. for Internet
telephony.
U
USB Universal Serial Bus. A specification to establish communication between devices and a
host controller (usually personal computers). USB is intended to replace many varieties of
serial and parallel ports. USB can connect computer peripherals such as mice, keyboards,
digital cameras, printers, personal media players, flash drives, and external hard drives.
UTC Coordinated Universal Time. The International Atomic Time (TAI) with leap seconds
added at irregular intervals to compensate for the Earth’s slowing rotation. Leap seconds
are used to allow UTC to closely track UT1, which is mean solar time at the Royal
Observatory, Greenwich.
W
WLAN Wireless Local Area Network.