5
1 DMR Introduction
This chapter mainly introduces the Digital Mobile Radio (DMR) standards, focusing
on the protocol principles and tendency of the digital technology.
DMR is an open digital radio standard for professional mobile radio users published
by the European Telecommunications Standards Institute (ETSI) in 2004. This
standard aims to achieve a high-efficient professional wireless communication
system with less complexity and low cost.
DMR standard covers three tiers:
Tier I: This tier is for license-free use in the 446MHz band. It utilizes 6.25kHz
FDMA technology, targeted at the business market. Updated recently, Tier I
supports trunking system and becomes available for the professional market.
Tier II: This tier is for conventional communication. It adopts two-slot 12.5kHz
TDMA technology and targets the professional market.
Tier III: This tier is for trunking and simulcast communication. Besides two-slot
12.5kHz TDMA technology, it also supports network management applications.
This tier is targeted at professional market.
Digital technology presents a predictable tendency of the wireless communication,
which delivers products of better communication quality, higher security, more
spectrum resource and richer functions compared with analog products.
Hytera adopts the DMR technology and develops the digital radio compatible with
analog work mode. Hytera DMR radios can convert analog signals into digital
signals, and transmits both data and voice. Digital signals can be enhanced via the
gain and transmitted in a wider coverage. Based on TDMA technology, digital radios
accommodate much more subscribers.
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