VS 2001
Technical Handbook
General Information
Page 2
Marconi Proprietary information
P/N: 779-0373/02
Revision 02
1.2
TETRA NETWORK OVERVIEW
A short overview of the TETRA radio communication system, adopted reference
standards, network infrastructures and user terminals are reported in this chapter.
TETRA stands for TErrestrial Trunked RAdio (Trans European Trunked Radio).
The TETRA standard relies on a thoroughly digital technology and it is able to offer
services and performances not yet available on alternative technologies. By using
TETRA Networks it is possible to obtain a greater data transmission rate thus more
information can be sent in a shorter time. This means that you can send longer
messages to all the TETRA terminal users or that a greater number of these can
be served under the same system resources. A typical TETRA application is the
management of a great number of mobile radio units involved in voice and data
communications. In TETRA systems, Voice and Data transmission services are
supported by a radio transmission interface which has the following main
parameters:
•
Channel spacing: 25 kHz or 12.5 kHz;
•
Modulation:
π
/4 DQPSK;
•
Gross channel rate: 36 kbits/s (25 kHz channels) or 18 kbits/s (12.5 kHz
channels);
•
Access mode: TDMA with 4 timeslots (25 kHz) or with 2 timeslots (12.5 kHz);
•
Transfer rate: 7.2 kbits/s per timeslot;
•
Max transfer rate: 28.8 kbits/s (unsecured transmission);
•
Transfer rate (secure transmission): up to 19.2 kbits/s.
An example of a TETRA system architecture is shown in Fig. 1.1.
The main system elements are:
•
Radio base stations (covering the whole network);
•
Switching and control units;
•
Network management system;
User terminals are divided in:
•
Hand-held
radio;
•
Vehicular
radio;
•
Fixed station (desktop).
