What is MOTOTRBO?





Outside Motorola MOTOTRBO is known as DMR. DMR is an acronym for Digital Mobile Radio and is an ETSI standard for land mobile radio communications in the 66-960MHz band. The standard defines a two-slot TDMA channel access method thus allowing two simultaneous voice or data calls on a 12,5kHz radio channel.

The standard is divided into four chapters:



The standard also refers to three tiers:
  • DMR Tier 1 refers to low-power consumer and business applications, using a maximum of 0,5W ERP. To date there are no known manufacturers of DMR Tier 1 equipment.
  • DMR Tier 2 covers licensed conventional radio systems and radios operating in the 66–960MHz PMR frequency bands. There are numerous manufacturers of DMR Tier 2 compliant equipment and the majority of radio systems today are also Tier 2.
  • DMR Tier 3 covers trunking operation in frequency bands 66–960 MHz. It supports voice and short messaging handling similar to TETRA and MPT1327.
MOTOTRBO Conventional and IP Site Connect are compliant to DMR Tier 2. Capacity Plus is a proprietary implementation from Motorola based on the DMR Tier 2 air interface. Capacity Max supports DMR Tier 3 operation. More about these systems below.

The standard does not define a vocoding mechanism so all DMR manufacturers have agreed to use the ABME+2 algorithm from DVSI.

Some of the benefits of MOTOTRBO include:


Double spectral efficiency: two channels on a 12,5kHz frequency allocation. One timeslot could be carrying a voice call while the other could be used to send data. With Capacity Plus; Linked Capacity Plus;Capacity Max and Connect Plus, it is possible to pool these slots and allocate them automatically thus increasing the number of number of users that can be supported per channel.

All MOTOTRBO radios (except  the SL4000) support analogue mode operation that allows them to be used on legacy analogue systems and gives the customer the opportunity to easily and smoothly migrate to digital when they are ready.
DP4801

Since a portable two way radio will only transmit 50% of the time when operating in digital mode, the average current consumption can decrease by up to 40% - this results in longer battery life.

Through Motorola's Application Partner programme, customers can source and/or develop software applications around their MOTOTRBO radios. Features like GPS and indoor tracking; job ticketing; data and text messaging extend the use of two way radio beyond just push to talk.

Features like Transmit Interrupt allow a manager to break into an ongoing call to pass an important message. Similarly, Transmit Interrupt can be used to free up a channel to pass an emergency call. The messaging required to interrupt a transmission is sent to the transmitting radio via the other slot (since the radio is only transmitting on one slot).

MOTOTRBO radios are extremely good at filtering background noise. This makes these radios well suited for users who work in noisy environments. Together with the XBT headset or INC and ANC speaker-microphone, users can communicate with ease.
No additional hardware needed for the same capacity. Antennas and RF filtering equipment can be reused.

Since MOTOTRBO radios use Forward Error Correction in digital mode, the amount of useable RF coverage is increased. A location where an analogue signal would difficult to hear will be easily readable in digital mode.


MOTOTRBO radios are able to operate with other DMR vendors equipment. This offers the customer peace-of-mind knowing that their investment in this technology is a safe one.

Since MOTOTRBO radios operate in the existing PMR frequency bands, customers don't need to replace antennas or RF filtering equipment when upgrading to digital.

MOTOTRBO radios support Private; Group and All (Broadcast) calls. This allows customers to divide their radio fleet into workgroups and reduces fatigue due to radio chatter.

Some MOTOTRBO radios support GPS and Bluetooth allow the location of users to be tracked ensuring efficiency and worker safety.

MOTOTRBO infrastructure (repeaters) can be configured for a number of different topologies:
  • Single Site Conventional. A single or multiple repeaters on a single site which provides service to a smaller number of users in a defined coverage area.
  • IP Site Connect. A multiple repeaters linked via IP which provides service to a smaller number of users in a larger area. IP Site Connect supports a maximum of 15 sites (repeaters). IP Site Connect systems can be linked via a third party application (PC) to provide additional coverage.
  • Single Site Capacity Plus. A semi-trunked system consisting of up to eight repeaters all located on one site and supporting a large number of users in a defined area. For data intensive applications, up to 12 data revert repeaters can be added to pass radio to server data such as GPS**. Capacity Plus does not require a server and all the intellegence to manage network operation is built into the repeaters themselves.
  • Multi Site Capacity Plus. A semi-trunked system consisting of up to eight repeaters and up to 15 sites, supporting a large number of users across a wide area. For data intensive applications, some of these repeaters can be configured as data revert channels to pass radio to server data such as GPS**. Capacity Plus does not require a server and all the intelligence to manage network operation is built into the repeaters themselves.
  • Capacity Max. A wide area trunked system supporting up to 250 sites and up to 15 repeaters per site. One slot on each site is allocated as a control channel (Capacity Plus does not use a control channel). Capacity Max uses centralised control and distributed call processing: this means that there is a Capacity Max System Server managing network operations but the calls themselves are passed between the repeaters without the need for a central node (core router). Capacity Max supports DMR Tier 3 operation.
** Capacity Plus is a proprietary implementation from Motorola based on the DMR Tier 2 air interface. Capacity Max supports DMR Tier 3 operation.


[Rev. 10.04.17]
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