DMR Ham Radio

 Digital Radio Mondale

Digital mobile radio (DMR) is an open digital mobile radio standard defined in the European Telecommunications Standards Institute (ETSI) Standard TS 102 361 parts 1–4  and used in commercial products around the world. DMR, along with P25 phase II and NXDN are the main competitor technologies in achieving 6.25 kHz equivalent bandwidth using the proprietary AMBE+2 vocoder. DMR and P25 II both use two-slot TDMA in a 12.5 kHz channel, while NXDN uses discreet 6.25 kHz channels using frequency division.

DMR was designed with three tiers. DMR tiers I and II (conventional) were first published in 2005, and DMR III (trunked) was published in 2012, with manufacturers producing products within a few years of each publication. The primary goal of the standard is to specify a digital system with low complexity, low cost and interoperability across brands, so radio communications purchasers are not locked into a proprietary solution. In practice, many brands have not adhered to this open standard and have introduced proprietary features that make their product offerings non-interoperable.

The DMR interface is defined by the following ETSI standards:TS 102 361-1: Air interface protocol

 The DMR standard operates within the existing 12.5 kHz channel spacing used in land mobile frequency bands globally, but achieves two voice channels through two-slot TDMA technology built around a 30 ms structure. The modulation is 4-state FSK, which creates four possible symbols over the air at a rate of 4,800 symbols/s, corresponding to 9,600 b/s. After overhead, forward error correction, and splitting into two channels, there is 2,450 b/s left for a single voice channel using DMR, compared to 4,400 b/s using P25 and 64,000 b/s with traditional telephone circuits.DMR covers the RF range 30 MHz to 1 GHz.

The DMR Association and manufacturers often claim that DMR has superior coverage performance to analogue FM. Forward error correction can achieve a higher quality of voice when the receive signal is still relatively high. In practice, however, digital modulation protocols are much more susceptible to multipath interferenceand fail to provide service in areas where analogue FM would otherwise provide degraded but audible voice service. At a higher quality of voice, DMR outperforms analogue FM by about 11 dB. But at a lower quality of voice, analogue FM outperforms DMR by about 5 dB

DMR Tier I 

DMR Tier I products are for licence-free use in the European 446 MHz band. In the US, the 446 MHz range is primary US Government with the amateur radio service a heavy secondary user. Some DMR radios that make it across the ocean have caused interference issues with licensed amateur operations. Tier 1 equipment is FDMA.

This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power

 DMR Tier II

DMR Tier II covers licensed conventional radio systems, mobiles and hand portables operating in PMR frequency bands from 66–960 MHz. The ETSI DMR Tier II standard is targeted at those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. ETSI DMR Tier II specifies two slot TDMA in 12.5 kHz channels. A number of manufacturers have DMR Tier II compliant products on the market.


DMR Tier III covers trunking operation in frequency bands 66–960 MHz. The Tier III standard specifies two slot TDMA in 12.5 kHz channels. Tier III supports voice and short messaging handling similar to TETRA with built-in 128 character status messaging and short messaging with up to 288 bits of data in a variety of formats. It also supports packet data service in a variety of formats, including support for IPv4 and IPv6. Tier III compliant products were launched in 2012.


Two-Slot TDMA DMR Tier II/Tier III occupies a 12.5 kHz bandwidth that two channels share using Time-Division Multiple Access (TDMA). This results in spectrum efficiency of 6.25 kHz per channel. Comparing the spectrum efficiency of DMR to a wideband analog FM, DMR only uses 25% of the bandwidth per talk channel. Each channel can carry either voice and/or data depending on system design. The two time slots are called Time Slot 1 (TS1) and Time Slot 2 (TS2). For the amateur, this means one repeater allows two separate channels at the same time. Currently most amateur DMR repeater system implementations utilize both channels for voice and some limited text messaging. Typically one channel (time slot) is used for wide-area and the second is local and regional Talk Groups. For repeater operators, a single two-slot TDMA repeater offers a significant savings over two standalone repeaters to obtain two separate communication channels as only one repeater, one duplexer, and one antenna system is required. The utilization of TDMA offers about a 40% battery savings on transmit, extending talking time over non-TDMA and analog transmissions for portable users. The two-slot TDMA implemented in DMR uplinks (portable/mobile to repeater) uses a 30-ms window for each time slot, the 30-ms is further divided into a 27.5-ms frame and a 2.5-ms gap. This means when transmitting, your transmitter is only turned on for 27.5ms every 60ms, resulting in extended battery life for portables. The DMR repeater (downlink) transmits a continuous data stream even if only one timeslot is being used; the 2.5-ms uplink gap is replaced with a CACH burst (Common Announcement Channel) that is used for channel management and low speed signaling. The 27.5-ms frame consists of a total of 264-bits; 108-bit payload, 48-bit SYNC or embedded signaling, and a second 108-bit payload for a total of 216-bits of payload per frame. The vocoder must compress 60-ms of audio with FEC (forward error correction) into 216-bits of data for transmission. The 2.5ms-gap is used for guard time to allow PA ramping and propagation delay. Talk Groups Talk Groups (TG) are a way for groups of users to share a time slot (oneto-many) without distracting and disrupting other users of the time slot.

It should be noted that only one Talk Group can be using a time slot at a time. If your radio is not programmed to listen to a Talk Group, you will not hear that Talk Group’s traffic. The DMR-MARC Mototrbo™ network supports a number of Talk Groups on TS1 including World Wide (TG1, PTT), North America (TG3), and World Wide English (TG13). TS2 is for local, state, and regional Talk Groups. The DCI/TRBO network uses TG3163 for North America and TG3161 for World Wide, and TG3 for World Wide English on TS2. Check with your local repeater operator to find out what Talk Groups/Time Slots are available on a repeater. The DMR standard also supports private calls (one-to-one), encryption, and data. Private calls are not allowed by most of the amateur networks and many consider private calls not amateur friendly; private calls tie up a large number of repeater time slots across the network. Encryption is not legal on amateur radio in the USA but is allowed in Canada! Data and text messaging is supported on some networks. For simplex traffic, the accepted standard in the amateur community is to use TG99 on TS1 with CC1. When programming your DMR radio, you may find it easier to program multiple Talk Groups for receive. I have two RX Group lists programmed in my radios, one for TS1 and one for TS2; this allows my radio to listen to all the possible Talk Groups used on a time slot when I have my radio set to any channel. There are Talk Groups implemented for individual states and regional on many networks. Some Talk Groups are available all the time, while others only at preprogrammed times. Some Talk Groups require a local 6 user to PTT on the Talk Group to activate it for a period of time. Since only one Talk Group can be active at a time on a time slot, many systems will disable other Talk Groups when a local user is active on a different Talk Group on the time slot. Be ham friendly and try to use Talk Groups that tie up the fewest number of repeaters if you are going to have a long QSO. Further information about specific

Talk Groups can be found on the DMR-MARC, DCI, and regional group websites. Zones User DMR radios support Zones. A Zone is just a grouping of individual channels. Some model radios may limit the number of channels per Zone and the number of Zones allowed. You could program Zones for local channels (DMR or analog), another Zone for a neighboring state, and a Zone for business and government channels. If you do program non-amateur channels in your radio, make sure they are RX only unless you are licensed or authorized to use them as per FCC 90.427(b); otherwise you will be in violation of FCC R&Rs and enforcement action could be taken against you. If you have a VHF model, you could program a Zone for all the possible NWS Weather Channels (again, make sure you program the channels as receive only).


Zones are just a way to manage large number of channels, much like file folders or directories on your computer. Color Codes DMR repeaters use Color Codes (CC) much like analog repeaters use CTCSS (PL) or DCS. To access a repeater you must program your radio to use the same CC as the repeater. There are 16 different CCs (CC0- CC15). The use of Color Codes is not optional on DMR systems. If your Color Code is not set correctly, you will not be able to access the repeater. The only real purpose of using different Color Codes is when multiple repeaters operating on the same frequency have overlapping coverage areas. Code Plugs A code plug is simply a radio’s configuration file. Using a manufacturer’s programming software you configure the channels and operating parameters of a radio. This file is uploaded to the radio and typically should also be saved on you computer as a backup. You can also download the code plug from a radio to modify it. Building a code 7 plug can take many hours, especially if you want to program hundreds of channels. The code plug can also contain a Contact List of Radio IDs, call signs, and names to be displayed. You can find copies of configured code plugs on the web for different models of radio; check out the different Yahoo DMR groups. All DMR radios support a limited number of entries in the Contact List; you can download Code Plugs with the Contact List populated using a generator on the DMR-MARC home page. Scanning All DMR radios allow you to configure scanning of channels. Remember, you will only hear traffic on the frequency, time slot, and groups you have programmed on a channel. I typically scan both time slots on my local repeater and a simplex channel I use; you can also scan analog channels mixed with the digital channels. Scanning will decrease the battery life on your radio. Roaming Roaming is not supported on all DMR radios. Check your owner’s manual or manufacturer website to see if roaming is supported. In some radios it may be an additional cost option. Roaming is NOT scanning. Roaming is similar but different. Roaming is designed to have your radio automatically select the best channel if your current channel’s Receive Signal Strength Indicator (RSSI) falls below a defined level as you move throughout the coverage area of a group of repeaters that carry the same Talk Groups on the same time slots. You should select channels that have the same time slot and receive groups configured; if you do not, roaming may not work correctly. Repeaters can be configured to transmit beacons at predefined intervals of inactivity so roamers will be on the correct channel. Without the repeater beacons, roaming will still work, but the radio will only change channels if it hears a repeater on the air. Roaming would be really great if all the DMR repeaters were on the same set of repeater pairs across the country, but it is too much to expect the Repeater Councils to work together for a unified rebanding of existing coordinations. It would also help if the different DMR networks could agree on which time slots were used by which Talk Groups. Wouldn’t it be really nice to be able to program a dozen different frequencies, with a variety of common Talk Groups, on the same time slots in your radio and be able to travel across North America and be able to access all DMR repeaters? 8 Simplex On the professional side of DMR, Talk-Around refers to oper

DMR Association 

In 2005, a Memorandum of Understanding (MOU) was formed with potential DMR suppliers including Tait Communications, Fylde Micro, Selex, Motorola, Hytera, Vertex Standard, Kenwood and Icom to establish common standards and interoperability. While the DMR standard does not specify the vocoder, MOU members agreed to use the half rate DVSI Advanced Multi-Band Excitation (AMBE) vocoder to ensure interoperability. In 2009, the MOU members set up the DMR Association to work on interoperability between vendors equipment and to provide information about the DMR standard.  Formal interoperability testing has been taking place since 2010. Results are published on the DMR Association web site. There are approximately 40 members of the DMR Association. The standard allows DMR manufacturers to implement additional features on top of the standards which has led to practical non-interoperability issues between brands, in contravention to the DMR MOU.

Many manufactures are making DMR Rigs at a low cost Be sure of what you are buy to be compatable. Kenwood, Tytera, Motorola, Vertex Standard are the most compatable with US operation. Most USA Systems are UHF (70cm) based.

A free DMR ID number is required to use repeaters and DMR Brandmeister/IPSC2 and DMR plus reflectors. Fill out registration you will recieve Number by E-Mail


Click on registration tab at top


 DMR Repeaters

Accessing a DMR Repeater When you want to access a DMR repeater, you must have the frequency, Color Code, and Talk Group set correctly. When you key your transceiver, you send a signal to the repeater and the repeater responds back to you to acknowledge you can transmit your message. If you do not receive the repeater’s acknowledgement, your radio will stop transmitting and you will hear a negative confirmation tone. This is one of the advantages of TDMA: allowing bidirectional communications between user and the repeater when transmitting. The repeater can also signal your radio to stop transmitting if there is contention on the network because more than one station is transmitting at a time. 9 Not all DMR repeaters are interconnected on the Internet. Internet connectivity may not be available at the repeater site, or not available at a reasonable cost. Some repeater operators may just prefer to keep their repeater for local usage only, or maybe only want it connected to a small local/regional network, without connecting to the larger world wide networks.

DMR Maryland Repeaters 

Frequency Offset Tone Location County Call  Use Operational status
  442.2375 +5 MHz MT Ashton Montgomery K3UCB OPEN ON-AIR
  443.7875 +5 MHz MT Annapolis Anna Arundle W4ATN OPEN ON-AIR
  442.4875 +5 MHz MT Rockville Montgomery N3JFW OPEN Testing
  443.1875 +5 MHz MT Charlotte Hall St. Marys K3OCM OPEN ON-AIR
  443.8500 +5 MHz MT Towson Baltimore K3OCM OPEN ON-AIR
  444.6500 +5 MHz MT Upper Marlboro Prince Georges N3LHD OPEN ON-AIR
  145.1700 -600KHz MT Thurmont Frederick K3LAO


DMARC Talkgroup List

Talkgroup DCI / TS Detail / Use
Alabama 3101 / 1 Alabama Statewide on TS-1
AllStar Link 2B 3167 / 2 DMR to AllStar Link Node: 27575 on TS-2
Arkansas 3105 / 2 Arkansas Statewide on TS-2
Audio Test 9999 / 2 Audio Testing, VU meter with Streaming
BC 3027 / 1 British Columbia Regional on TS-1
Bridge 3100 / 2 Bridge-to-Bridge TG on TS-2 (Info, List)
California 3106 / 1 California Statewide on TS-1
Canada 302 / 2 Canada-wide on TS-2
Colorado 3108 / 2 Colorado Statewide on TS-2
Comm 1 3777215 / 1 Original Talkgroups from 2009 used by TRBO-6 after dropping All Call
Comm 2 3777216 / 2
DCI 1  (Primary)      3160 / 1 DCI Repeater Networks only on TS-1
DCI 2  (Secondary) 3162 / 2 DCI Repeater Networks only on TS-2
EchoIRLP 8700 / 2 EchoLink and IRLP Portal on TS-2
Fusion 3182 / 2 Yaesu Fusion System on TS-2 (no gateway)
Georgia 3113 / 1 Georgia Statewide on TS-1
HyteraUSA 4962 / 2 USA Hytera Reflector
Illinois 3117 / 2 Illinois Statewide on TS-2
iCall 8952 / 2 International Hailing Only, then move to TAC 1
I-5 3168 / 1 Interstate-5; West coast states, TS-1
Iowa 3119 / 2 Iowa Statewide on TS-2
Local 1 3181 / 1

Local Repeater TS 1 / DCI c-Bridge Manager / Same IPSC Network Chatter

Local 2 3166 / 2

Local Repeater TS 2 / DCI c-Bridge Manager / Same IPSC Network Chatter

Massachusetts 3125 / 1 Mass Statewide on TS-1
Michigan 1 3126 / 1 Michigan Statewide on TS-1
Michigan 2 103126 / 2 Michigan Statewide on TS-2
Mi-5 Statewide 1 51 / 1 Mi-5/CMEN Group Statewide on TS-1
Mi-5 Statewide 2 52 / 2 Mi-5/CMEN Group Statewide on TS-2
NoCo 3171 / 1 NoCo-wide on TS-1
North America 3163 / 2 North America on TS2
Ohio 3139 / 1 Ohio Statewide on TS-1
Oregon 3141 / 1 Oregon Statewide on TS-1
Ontario 3023 / 2 Ontario Canada Regional on TS-2
PA-525 3185 / 2 52.525 FM Remote Base
Parrot 9998 / 1 Parrot Echo Test Server on TS-1
Penn 3142 / 1 Pennsylvania Statewide TS-1
PNW 1 3187 / 1 Pacific Northwest Network on TS-1
Regionals 31xx / 2 MARC Regionals, All six on TS2
South Carolina 3145 / 2 South Carolina Statewide TS-2
TAC 1 (on TS2) 8951 / 2 TAC 1 is worldwide PTT TS-2, Any Language
TAC 310, 311, 312 310-312 / 2 TAC 310 311 312 are fully PTT on TS-2, English (Info)
TAC English 123 / 2 TAC E is fully PTT on TS-2, Worldwide English
Texas 3148 / 2 Texas Statewide TS-2
Tennessee 3147 / 2 Tennessee Statewide TS-2
Utah 3149 / 2 Utah Statewide TS-2
USA 1776 / 2 USA based, Full or Part Time on TS-2
Wash 1 3153 / 1 Wash. Statewide on TS-1 (info)
Wash 2 103153 / 2 Washington Statewide on TS-2
Worldwide 3161 / 2 Worldwide (short use)
Worldwide English 13 / 2 Worldwide English
Local/Simplex 99/ 1 Simplex Operations pier2pier


Simplex Frequencies

National Digital Simplex Frequencies  (12.5Khz or less)

UHF 1) 441.0000   2) 446.5000   3) 446.0750   4-US & Europe 433.450
VHF 1) 145.7900   2) 145.5100
TG ID: 99  /  CC 1  /  TS 1  /  "Admit Criteria": Always  /  "In Call Criteria": TXI or Always
It is recommended that you contact the local area coordinating councils when using our suggested simplex frequencies to insure an interference free session.

 Listen to DMR Audio TDMA

                                      DMR Audio Transmission


 MD-380/390 programming Software/Firmware Download


DMR Codeplug for Maryland insert your call and DMR ID#

Connect Systems DMR

CS-700 codeplug

CS-750 Codeplug

CS-800 Codeplug

Tytera MD-380/390

TYT MD-380/390 codeplug



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