User manual

Glossary
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connection between them and then securely transport data packets over the connection.
R
RF Radio Frequency. Electromagnetic wave frequencies between about 3 kHz and about
300 GHz 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.
V
VPN Virtual Private Network. A network that is constructed by using public wires to connect
nodes. You can create networks using the Internet for transporting data, using security
mechanisms so that only authorized users can access the network.
W
WLAN Wireless LAN. A wireless computer network that links two or more devices using a wireless
distribution method (often spread-spectrum or OFDM radio) within a limited area such as
a home, school, computer laboratory, or office building.