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Introduction to DMR By KM6IRY What is Digital Mobile Radio (DMR)? - - PowerPoint PPT Presentation
Introduction to DMR By KM6IRY What is Digital Mobile Radio (DMR)? - - PowerPoint PPT Presentation
Introduction to DMR By KM6IRY What is Digital Mobile Radio (DMR)? A standard established by ETSI An European Telecommunications Standards Institute (ETSI) published worldwide standard to help reduce RF congestion. Uses 12.5 kHz channel width
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A standard established by ETSI
An European Telecommunications Standards Institute (ETSI) published worldwide standard to help reduce RF congestion. Uses 12.5 kHz channel width Time Division Multiple Access (TDMA) Effectively 6.25 kHz per channel
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DMR Tiers
Tier 1 (Unlicensed) - 2005
- FDMA, Consumer applications, .5 watt
- dPMR (446 MHz European unlicensed
service) Tier 2 (Conventional) - 2005
- 2-slot TDMA
- IP Connected
Tier 3 (Trunked) - 2012
- 2-slot TDMA
- Multi-channel, Multi-Site
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Two Repeaters in One
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Spectrum Efficient
Two 6.25 KHz repeaters (like D-Star) need Guard Bands between them if located near each other to co-exist without interference, thus taking more spectrum! The actual FCC emission designator for DMR is 7K6 or 7.6 KHz Bandwidth.
fc fc + 11.25 fc – 11.25 fc + 6.25 fc fc - 6.25 Guard Band as large as 10 kHz between channels Total BW= 22.5 kHz No Guard Band between 2 channels Total BW= 12.5 kHz
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Better Signal Quality
- No hiss, popping, or static
- Better RF range than older
digital technologies
- Forward Error Correction and
Cyclic Redundancy Check coders
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Better Battery Efficiency
For each hour of usage the TDMA radios show between 19% and 34% less battery capacity is required than for the FDMA models. 40 percent improvement in talk time in comparison with analog radios
http://dmrassociation.org
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Regional US Regional Sub-Regional/Statewides Repeater National
World Wide
Time Slot 2 Time Slot 1
Timeslots & Talkgroups
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