TETRA TErrestrial Trunked RAdio (TETRA), a two-way radio system is a modern standard for digital Private Mobile Radio (PMR) and Public Access Mobile Radio (PAMR). Digital radio standard for critical communication systems.

Benefits; 

• TETRA is perfect for critical data applications that require maximum reliability.
• Custom-built devices and networks.
• Wide coverage. & Big capacity.
• There are no additional airtime costs associated with commercial cell phone networks
• A high degree of control over system requirements, design, priorities, features, and operation – allows the system to be configured as required.

This system provides many advantages including flexibility, security, ease of use, fast call setup time, speed dial, group call, and direct mode. Flexibility to interface with other systems.

The foundation of the TETRA radio system consists of three modes;

• Voice plus Data (V+D)
• Direct Mode Operation (DMO)
• Optimized Packet Data (PDO)

At first, TETRA had many features that users needed, but in subsequent developments, TETRA provided additional functionality and improvements to keep pace with growing needs and as technology advances, including;

• Trunked Mode Operation, TMO
• Range Extension: The first TETRA radio has a maximum range of 58 km. In its development, TETRA can then reach a distance of up to 83 km.
• TETRA Enhanced Data Service (TEDS), TEDS is a new TETRA High-Speed Data, HSD, service that has been introduced. To achieve higher data rates, TETRA TEDS uses a different RF channel bandwidth and modulation scheme. Migration from the first TETRA technology to advanced TETRA has compatibility making migration easy.

Comparison between TETRA Radio and Digital Mobile Radio (DMR) is; 

TETRA radio

• Encryption is stronger
• Efficient data communication for GPS positioning, messaging, and more; automatic handover and roaming; authentication; direct mode communication; and private and conference calls. Terminal time-division full-duplex operation. On DMR is not available. 
• The TETRA frequency is lower than DMR, therefore the range is wider.
• TETRA has advantages both for medium to high-capacity trunk networks with high traffic volumes and low coverage areas, such as large industrial sites, large campuses, airports, and similar locations.
• TETRA (2 watts) has lower maximum RF Power than DMR and DMR (5 watts)
• TETRA has lower sensitivity than DMR, due to twice the bandwidth of the receiver
• TETRA only works in the UHF band, so the propagation effect also reduces the range capability

Digital Mobile Radio (DMR)

• DMR replacement for analog systems with all the advantages of digital solutions. DMR is best suited for large areas, and relatively low-traffic applications where simulcast provides the best performance.
• The DMR standard does not yet have a terminal that performs time-division full-duplex operations.
• DMR uses a robust fixed envelope modulation (the positive half wave) scheme that provides the same RF power and sensitivity as conventional analog systems.
• In the transition from analog to digital radio, DMR no longer needs to change the existing system.
• DMR was developed to replace analog two-way radio systems with pin-to-pin digital solutions, meaning the digital systems must perform the same coverage and application schemes. — repeater, multisite network, simulcast, and trunking — as analog network before, so there is no need to change the installation area to get the same coverage performance.