TETRA Radio System: Interview Questions and Answers

This page covers interview questions and answers on the TETRA (Terrestrial Trunked Radio) system.

Question -1: What is TETRA in mobile communication?

Answer -1: TETRA, which stands for Terrestrial Trunked Radio, is a digital mobile radio standard developed specifically for professional mobile radio (PMR) and public safety communication. TETRA is designed to provide secure, efficient, and reliable voice and data communication for organizations such as public safety agencies, transportation services, utilities, and other critical communication users.

TETRA is a set of standards developed by the European Telecommunications Standards Institute (ETSI). The key features of the TETRA radio system are as follows:

• Digital Communication: TETRA employs digital modulation and digital voice encoding, offering improved audio quality and resistance to interference compared to analog systems.
• Secure Communication: TETRA supports encryption and authentication features, ensuring the security of sensitive communications. This is particularly crucial for public safety and mission-critical operations.
• Efficient Spectrum Usage: TETRA optimizes spectrum usage by employing time-division multiple access (TDMA) technology. This allows multiple users to share the same frequency channel by dividing it into time slots.
• Group Communication: TETRA supports group communication features, allowing users to belong to talk groups and communicate with multiple individuals simultaneously. This is essential for coordination in emergency response scenarios.
• Integrated Data Services: TETRA supports not only voice communication but also data services, including messaging, location-based services, and telemetry.

Question -2: How does Tetra Radio Work?

Answer -2: TETRA (Terrestrial Trunked Radio) operates using digital radio technology and is specifically designed for professional mobile radio (PMR) and critical communication systems.

Let’s understand an overview of how TETRA radio works:

• TETRA uses digital modulation techniques, such as Quadrature Amplitude Modulation (QAM), to encode voice and data into radio signals. This results in improved signal quality and more efficient use of the available spectrum compared to analog systems.
• TETRA employs TDMA technology, dividing the available radio frequency into time slots. Each time slot can be allocated to different users or talk groups, allowing multiple users to share the same frequency channel without interference. This contributes to efficient spectrum utilization.
• TETRA supports both voice and data communication. Digital voice encoding ensures clear and secure voice communication. Additionally, TETRA can transmit various types of data, including short data messages, status updates, and other information critical to the users’ operations.
• Encryption and Security: TETRA systems prioritize security features. They often include encryption algorithms to protect communication from unauthorized access and eavesdropping. Authentication mechanisms are also employed to verify the identity of users and devices.
• Group Communication: TETRA supports group communication, allowing users to be organized into talk groups. Users within the same talk group can communicate with each other simultaneously, enhancing coordination and efficiency in scenarios such as emergency response or public safety operations.
• Infrastructure Components: TETRA networks consist of various infrastructure components, including base stations (cell sites or radio towers), switches, and control centers. Base stations facilitate communication between mobile radios, while the control center manages network resources and services.
• Interoperability: TETRA is designed to ensure interoperability among different manufacturers’ equipment. This allows users from different organizations or agencies to communicate seamlessly when using TETRA-compatible devices.

Question -3: What are the radio frequencies, channels, modulation, and bandwidth supported by TETRA Radio System?

Answer -3: There are two versions; TETRA-1 uses VHF, UHF, and 800 MHz bands. TETRA-2 uses frequencies up to 1.9 GHz.