Digital Mobile Radios are wireless communication systems and devices based on radio frequencies that operate between 30 MHz (Megahertz) and 1000 MHz, also known as 1 GHz (Gigahertz) (generally using the UHF or VHF frequencies), and over which the communication lines move across both ends. Digital Mobile Radio or DMR for short is an open standard or protocol for Digital Mobile Radio defined by the European Telecommunication Standards Institute (ETSI) and used in commercial products worldwide. Digital radio is the transmission and reception of voice that is processed into numerical patterns, or “digits”. Digital radio is the use of digital technology to transmit or receive across the radio spectrum and may offer additional features such as GPS, Text Messaging, Live Dialing, Call-ID Emergency Alarm Functions, Man-down Functions, IP connectivity, and many other applications, and these not owned by analog radio. This DMR frequency range is divided into two categories:

• Very High Frequency (VHF) – Range between 30 MHz and 300 MHz
• Ultra-High Frequency (UHF) – Range between 300 MHz and 1 GHz.

There are three levels of Digital Mobile Radio (DMR) operation: Tier I for non-licensed conventional, Tier II for licensed conventional, and Tier III for trunking.

• Tier I (unlicensed): Digital Mobile Radio (DMR) works in Direct Mode (unit-to-unit) on public frequencies. A Tier 1, Digital Mobile Radio (DMR) device is best suited for individuals, recreational venues, small retailers, or other situations that don’t require large area coverage.
• Tier – II (conventionally licensed): This grade is intended to replace conventional/analog radio systems directly. This Digital Mobile Radio System operates under an individual license working in Live Mode (unit-to-unit) or using a Base Station (BS) for a repeat. It has a wide area coverage rate and is targeted at users who “require spectral efficiency, advanced voice features, and integrated IP data services in licensed bands for high-power communications.”
• Tier III (trunked license): DMR trunking systems operate under individual licenses with a controller function that manages communications automatically. It also supports packet data services in multiple formats, including support for IPv4 and IPv6. It is ideal for organizations that want the full benefits of managed trunking, voice, and data solutions.

Bandwidth usage on digital mobile radio is more efficient than analog radio. The modulator and demodulator on digital radio are an additional part compared to analog radio. Along with the increasing number of radio communication users in one network, the radio system that uses a digital mobile radio system will be more effective.

Key Benefits of Digital Mobil Radio (DMR)

• Double Channel capacity with 2-Slot, TDMA (Time division multiple access) technology so that one frequency can be divided into 2 slots, thus saving frequency. In this case, one slot can be used as a data line and one slot can be used as a voice line or both can be used as a voice line.
• Better Audio Quality
• Advanced Encryption to Secure Communication & Data
• Abundant Data Applications
• Analog & Digital Compatible
• Improved Battery Life.