Introduction to Digital Mobile Radio (DMR)

Amateur Radio Edition

Presented by Ryan Owens, KJ4SHL

The DMR Logo is a property of the DMR Association Ltd and is used with permission.

What is Digital Mobile Radio

• Commonly Known as “DMR”• An ETSI Published Worldwide Standard• Commercial Radio Industry Standard• Spectrally Efficient (12.5 kHz bandwidth for two channels)• Uses TDMA and ABME+2.• Supported by many Radio Manufactures

The DMR StandardETSI TS 102 361 (1~4)

• Tier 1 (Unlicensed)• FDMA

• Consumer applications, maximum of 0.5w RF power, European PMR446 band

• Limited number of channels and no use of repeaters, no use of telephone interconnects, and fixed/integrated antennas.

• Tier 2 (Conventional)• Two-slot TDMA in 12.5kHz channels

• Connect multiple sites over IP/RF (vendor specific)

• Tier 3 (Trunked)• Two-slot TDMA in 12.5kHz channels

• Centralized controller, dedicated control channel

Amateur Radio Uses Tier 2

DMR Association Members

ZTE

*Not a complete list The DMR Logo is a property of the DMR Association Ltd and is used with permission.

Benefits of Using DMR

• Allows Two Simultaneous Voice/Data Transmissions using a Single Repeater

• Improved Audio Performance Over Analog

• More Efficient Use of Radio Spectrum

• Capable of Being Linked to Repeaters Worldwide

• Longer Battery Life

• Many Radio Manufacturers

• Text Messaging

• Roaming

• APRS (MOTODMR and BrandMeister)

Two Channels – One Repeater

Each TDMA cycle is 60ms long, containing two 30ms time slots.

Half the Channel Bandwidth

Traditional Analog25 kHz

1 Channel1 Carrier/Repeater

DMR12.5 kHz

2 Channel1 Carrier/Repeater

Improved Performance

• Forward Error Correction (FEC) and Cyclic Redundancy Check (CRC) Coders

• Consistent performance throughout coverage area with no gradual fade at the fringes.

• Background noise reduction.

Better Battery Life

By cutting the effective transmit time in half, two-slot TDMA can enable up to 40% improvement over analog radios.

DMR digital devices can also include sleep and power-management technologies that increase battery life.

DMR TerminologyTerm DefinitionTime Slot Your transmit signal is broken into 30mS digital packets and the

transmitter switches on and off rapidly. Doing this allows two signals to share the same channel at the same time.

Color Code A color code is used to identify a system. Different color codes are used to identify different systems (Think PL or DPL Tone except it not optional).

Radio ID A unique number assigned to each radio on the DMR Network.

Codeplug Radio configuration file.

CPS Customer Programming Software, which is the software used to program a radio.

Admit Criteria Determines when voice or data is allowed to be transmitted on the channel. This is used to prevent a radio from transmitting on channels that are already being used.

Roaming Automatically selects a better channel if your current channel’s Receive Signal Strength Indicator (RSSI) falls below a defined level.

Zone Grouping of individual channels.

Call Setup

DMR• Frequency• Offset• Color Code* (0-15)• Time Slot (TS 1 or 2)• Call Type - See Next Slide• Assign Radio ID

Analog• Frequency• Offset• PL or DLP Tone (Optional)

*The use of Color Codes is not optional on DMR systems.

DMR Call Types

Term DefinitionGroup Call (Talkgroup) One-to-many group of users.Private Call One-to-one individual call to a single user.All Call One way voice communication between one radio

with all radio users within the same logical channel(Rarely use in Amateur Radio outside of simplex).

Call Alert This feature allows the initiating radio to essentially page another radio user. If the user presses the PTT a Private Call to the initiator of the Call Alert is started.

Radio Check This feature allows the initiating radio to check if a target radio is active within the system without notifying the user.

Getting Started

1. Request a User ID at radioid.net

2. Obtain DMR radio, programing cable and software.

3. Research local DMR repeater utilizing online resources like Repeater Book or Brandmeister network map.

4. Gather up a list of Talkgroups that interest you do your research not every Talkgroup is available on all repeaters/networks.

5. Program you radio.

Portable Radios Mobile RadiosLow Tier [China / Ham Quality]

• TYT MD-380 $97• AnyTone AT-D868UV* $178• CS750 $239

Mid Tier [Commercial Grade Single Band]

• Motorola XPR6550 (Used Market EOL)• Motorola XPR3500e• Hytera PD682/782

High Tier [Commercial Grade Single Band]

• Motorola XPR7550e• Kenwood NX-5300• Hytera PD982

Low Tier [China / Ham Quality]

• TYT MD-9600* $299• CS800D* $299

Mid Tier [Commercial Grade Single Band]

• Motorola XPR4550 (Used Market EOL)• Motorola CM300d / XPR2500• Hytera MD622/652

High Tier [Commercial Grade Single Band]

• Motorola XPR5550e• Kenwood NX-5000• Hytera MD782

*Dual Band

Baofeng

Buyers Beware!!!

DMR Networks

cBridge• Supports only Motorola

repeater hardware• Connect to others cBridges via

CCLinks.• Defacto standard in the

Americas until BrandMeister• Repeater SysOp Centric

BrandMeister• Decentralized network active in

43 countries running a total of 55 Master servers.• Supports Motorola, Hytera,

MMDVM, cBridge, and other protocols. • Encourage the use homebrew

equipment.• User Centric

Others: DMR Plus - Original Network Started in Europe (Reflector Based) | SmartPTT Software

Repeaters in the West Central Florida AreaCall Location Frequency

OffsetColor Code

Network

KJ4SHL Tampa Airport 442.600 + 1 MOTODMR

KJ4SHL St Pete Downtown 444.9625 + 1 MOTODMR

KJ4SHL Tampa Downtown (Coming Soon) 1 MOTODMR

KJ4SHL Drew Park 442.6125 + 15 BrandMeister

W4CLL Tampa East (VHF) 145.410 - 5 FL-DMR

W4CLL Tampa East 443.775 + 1 FL-DMR

W4VCO Lakeland 444.275 1 K4USD

N4SER Sarasota 444.700 + 1 DMR-SE

*Not a complete list

Popular TalkgroupsTALKGROUP NAME Group Call DistributionWorldwide 1 WorldwideRegional Local 2 LocalNorth America 3 North AmericaMARC Worldwide English 13 WorldwideBM Worldwide 91 WorldwideBM North America 93 WorldwideBridge-3100 3100 WorldwideTAC-310 310 WorldwideTAC-311 311 WorldwideFlorida 3112 WorldwideParrot 9998 Worldwide

West Central Florida (WCF Local) Talkgroup

Serves the following ten counties in Florida: Charlotte, Desoto, Hardee, Highlands, Hillsborough, Manatee, Pasco, Pinellas, Polk, Sarasota.

Talkgroup Number: 2

Several repeaters are connected in the Tampa Bay area. Talkgroup is also available on BrandMeister under the cluster name “Tampa Bay”.

DMR Simplex Frequencies

Here is a list of recommended simplex frequencies to be used with DMR in the United States.FREQUENCY BAND TALKGROUP ID TIMESLOT COLOR CODE441.0000 UHF 99 1 1

446.5000 UHF 99 1 1

446.0750 UHF 99 1 1

433.4500 UHF 99 1 1

145.7900 VHF 99 1 1

145.5100 VHF 99 1 1

•Admit Criteria: Always•In Call Criteria: Follow Admit Criteria or Always

Good Operating Practice

• Examples of good operating practice for initial calls on the DMR networks include:• This is KJ4SHL monitoring West Central Florida• N4TP this is KJ4SHL on Local 9

• Spend most of your time listening, not talking. • Be a good neighbor and don’t hog the network.

• Move off the wide area Talk Groups for long QSOs.

• Don’t forget to ID!• Help the new users develop good operating practices. • Promote DMR to your friends.

Example Repeater Site

KJ4SHL St Pete Downtown444.9625 + CC1

Motorola SLR570055 watts (into Combiner)

400ft AGL

(Other Modes in Photo Analog, P25, NXDN)

Connected to the MOTODMR cBridge backhauled via HamWAN

Other Ways to Access DMR Networks

Hotspots

JumboSPOTZUMspot

STM32 DVM MMDVM

OpenSPOT

DV4mini

DV-MEGA

Other Digital Modes

Mode Access Modulation CodecD-Star FDMA GMSK AMBE+

Yaesu System Fusion FDMA C4FM AMBE+2

NXDN FDMA 4FSK AMBE+2

APCO P25 (Phase 1) FDMA C4FM IMBE

APCO P25 (Phase 2) TDMA H-DQPSK (Outbound) H-CPM (Inbound)

AMBE+2

DMR TDMA 4FSK AMBE+2

Tampa Amateur Radio Club Talkgroup

A new club Talkgroup is now available for TARC members.

Talkgroup Number: 8272 (TARC in DTMF)

Available only on KJ4SHL Tampa Bay Area repeaters.A BrandMeister connection will be available later date for users out of the area or who wish access with a hotspot.

Served by the MOTODMR cBridge.

Questions?