A DMR Repeater is basically like an analogue repeater but is digital and has two time slots, so basically it is like having two digital repeaters in one – on the same frequency.
DMR uses two-slot 12.5 kHz Time-Division Multiple Access (12.5 kHz TDMA). This is not compatible with the FDMA mode. 12.5 kHz TDMA is a globally recognized, approved standard for the professional two-way radio market which is used in the amateur environment also.
fig 1 tdma-structure-of-dmrDMR TDMA is configured to provide 6.25 kHz equivalent efficiency in an existing 12.5 kHz channel.
12.5 kHz TDMA methods for achieving 6.25 kHz efficiency in the 12.5 kHz channels offer:
Twice the transmission capabilities, with decreased spectral congestion. In contrast, a 6.25 kHz FDMA approach doubles the number of RF carriers and in the process increases the likelihood
of interference with existing systems.
Increased performance, reliability and functionality – while improving battery life by up to 40 percent compared to analog radio.
Two virtual channels that can be adapted on the fly to meet a wide range of needs, including increased capacity for voice calls and wireless data access, or for advanced control signaling during a call.
Standards-based platform, as 12.5 kHz TDMA is the recognized standard for professional and commercial two-way radio market in both Europe and the United States.
MotoTRBO DMR provides enhanced voice communication. When signal strength drops off with distance from the transmitter, analog signals become distorted, producing audible static as signal strength degrades.
By contrast, digital receivers use digital error correction technology to correct anything interpreted as an error in a signal. If the error cannot be corrected, then the signal is simply rejected. With digital error correction technology, audio quality is more consistent across a given coverage area, resulting in clearer voice communications throughout the coverage area, as compared to analog. This helps ensure the message gets through clearly.
MOTOTRBO also features background noise suppression to help ensure communication comes through loud and clear. The static and noise rejection helps your workforce to hear better in noisy environments.
Frequently Asked Questions
1. What is DMR?
DMR, which is short for Digital Mobile Radio, is a published standard for digital voice communications utilising TDMA technology. There are several manufacturers that build DMR radio equipment, including Motorola, Vertex Standard, Kirisun, Hytera and Connect Systems to name a few.
2. What is MOTOTRBO or TRBO?
MOTOTRBO, or sometimes called TRBO for short, is the brand name for Motorolas DMR capable radios.
3. What are the benefits of using DMR?
The common benefits of using DMR include:
Crystal-clear audio without background noise or static;, Text messaging capability, Integrated voice and data applications on one device, Up to 40% longer battery life as compared to similar analog FM operation.
4. Who can I talk to using DMR?
Using DMR, you can talk to other thousands of other DMR users world wide using hundreds of DMR repeaters located all over the globe. Unlike using IRLP or EchoLink where other repeaters are dialed-on-demand using a node number, DMR users can communicate with one another simply by selecting one of the available talkgroups or channels. The most commonly used talkgroups include:
World Wide talkgroup, North American talkgroup, Local, UK-Wide, Europe-Wide, World-Wide, UK English.
5. Does DMR provide better coverage than analog FM?
Not really. While DMR communication is completely static free, once it reaches the threshold of coverage, it will become unusable, whereas with analog FM, users may continue to be heard even when the signal is mostly noise. As such, usable coverage is very much subjective from one operator to another.
6. What special license will I need to be able to use DMR?
Users will only need their Basic Qualification license (Foundation M3/MM3/M6/MM6) to be able to use DMR on either the 2m or 70cm bands.
7. Is DMR compatible with D-STAR, Yaesus digital radio or NXDN?
No. These are separate digital technologies and are not compatible with one other.