23-04-2011, 03:35 PM
TETRA (TERRESTRIAL TRUNKED RADIO).pptx (Size: 458.92 KB / Downloads: 65)
TETRA (TERRESTRIAL TRUNKED RADIO)
WHAT IS TETRA
* Advanced Digital Radio Communications System for Public Safety Services, Utilities, Transport, Local Government, Military
* Operational throughout Europe, Asia-Pacific, Africa, South America and Middle East
* Standard promoted by ETSI
* Multi-vendor supply / interoperation
FREQUENCY RANGE
1. 400 MHz
380 - 400 MHz for public safety systems
410 - 430 MHz for commercial applications
2. 800 MHz for commercial applications
standard based on TDMA technology with 4 timeslot and 25 kHz band
TETRA is superior PMR technology
Individual and group communications
Direct mode communication between radios
Packet data and fast data transfer services
Over-the-air programming of radios
Frequency economy
Fast call set-up time
Security features
To ensure an open multivendor market, TETRA specifies the following essential interfaces:
Air Interface ensure the interoperability of terminal equipment
from different manufacturers.
Terminal Equipment Interface (TEI) facilitates the independent
development of mobile data applications.
Inter-System Interface (ISI) allows the interconnection of TETRA
Networks from different manufacturers.
Direct Mode Operation (DMO) guarantees communication
between terminals also beyond network coverage .
TECHNOLOGY OF TETRA
TETRA TDMA
4:1 TDMA (Time Division Multiple Access)
25 kHz carrier spacing
Digital modulation, /4 DQPSK at 36 kbits/s
Speech calls use one channel
Data calls can use up to 4 channels ( Data transfer rates up to 7.2 kbit/ s per channel)