User Guide
89
GLOSSARY
The following conventions are used in
this glossary:
(S)
Sepura product term
(T)
TETRA term
sf
Short form (abbreviation or
acronym).
Alarm Call
A call enabling a user to request assistance in case of an
emergency scenario threatening life and physical
condition. Alarm Calls have the highest priority on the
network. This call can trigger a sequence of customisable
events which may include ‘live microphone’ (allowing the
user to broadcast the situation to other radio users within
the talkgroup and the Dispatcher), an outgoing speech
call, position reports and status messages. (Alarm Calls
are sometimes loosely referred to as Emergency Calls.)
(T)
context key
User-programmable key on a Sepura radio that can be
customised to provide a shortcut to a menu option, such
as the Contacts list or Talkgroups. Radios may typically
have left, centre and right context keys. (S)
Direct Mode Operation (DMO)
The facility for TETRA radios to communicate directly
with each other without using the TETRA infrastructure.
Also referred to as half duplex operation (one user talks
at a time). (T)
DMO gateway / Direct Mode Operation
gateway
A device that allows users working in Direct Mode
Operation to communicate with users in Trunked Mode.
This is often used to extend the working range of a radio.
(T)
DMO repeater / Direct Mode Operation
repeater
A radio acting as a repeater provides a service to other
radio users. It extends the range and enhances the
reliability of Direct Mode communication compared with
basic direct communication between the radios. (T)
End-to-End Encryption (E2EE)
Encryption of the total communication link (from one end
to the other) without intermediate decryption, required for
maximum security.
full duplex
A channel providing simultaneous transmission in both
directions, allowing both parties to speak and listen at the
same time. This is achieved by using two timeslots on a
single TETRA carrier frequency to establish
communication back and forth. The most common use of
this system is in telephone systems around the world.
Push-To-Talk switches are not needed during this
method of communication.
gateway
A device which interfaces the TETRA network with other
private or public telecommunications networks, such as
PSTN and ISDN. See also DMO gateway and GMO. (T)
group call
A call made by one radio user to other users within a
nominated talkgroup. Groups are set up on the radio (also
known as talkgroups) that contain other radio users either
performing a similar role or who are within a distinct
location. This type of call is initiated when the user
presses the PTT button on the radio. Only one person can
talk at any time during these calls. (T)
Group Short Subscriber Identity (GSSI)
Short form TETRA group identification number. sf. (T)
half duplex
A system that only allows the transmission of a radio
signal in either direction, but not simultaneously.
Meaning, only one person can speak and one (or more)
people can listen at any given time. The majority of two-
way radios only provide half duplex communication.
ISSI
Individual Short Subscriber Identity. sf. (T)
keypad lock
a) A function on a device, such as a mobile phone or
computer, that prevents a user accidentally activating
functions using the keypad or to prevent access to the
functions for security reasons.
