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Introduction to DMR

DMR, or Digital Mobile Radio, is an Open Standard defined by the European Telecommunications Standards Institute (ETSI), and used in commercial and amateur products around the world.

Designed to operate within the existing 12.5 kHz channel spacing used in licensed land mobile frequency bands globally AND to meet future regulatory requirements for 6.25 kHz channel equivalence.
  • Affordable digital systems with low complexity.
  • DMR products are sold in all regions of the world.

The DMR protocol covers:
  • Unlicensed (Tier I)
  • Licensed Conventional (Tier II)
  • Licensed Trunked (Tier II)

DMR, similar to P25 Phase II, both use two-slot TDMA (Time Division Multiple Access) in a 12.5 kHz channel, while NXDN uses discreet 6.25 kHz channels using frequency division.

The primary goal of the DMR standard is to specify a digital system with low complexity, low cost, and interoperability across brands, so radio communications end users are not locked into a proprietary solution.

This being said, there are brands which have not adhered to this open standard and have introduced proprietary features that make their products incompatible with some networks.


Open Interfaces, Open Standards, and an Open Philosophy.

In 2005, a Memorandum of Understanding was formed with potential DMR suppliers to establish common standards and interoperability. Although the standard does not specify it, members agreed to use the half-rate DVSI Advanced Multi-Band Excitation (AMBE) vocoder to ensure interoperability.

In 2009, members established the DMR Association to further advance the standard and to maintain interoperability.

Formal testing has been taking place since 2010.


DMR and Ham Radio

  • All-digital network of over 400 repeaters in 37 countries.
  • More than 10,000 registered users
  • Repeaters are connected ALL the time.
  • Excellent voice quality and extended battery life.
  • Less than 1/3 the channel bandwidth of analog FM with twice as many voice channels!
  • Reliable and scalable choice in connectivity


Two-Slot TDMA

DMR Tier II / Tier II occupies a 12.5 kHz bandwidth with tow channels sharing using Time-Division Multiple Access (TDMA). This results in spectrum efficiency of 6.25 kHz per channel.

Bandwidth

Comparing spectrum efficiency of DMR to a wideband FM modulated signal, DMR only uses 25% of the bandwidth per talk channel. Each channel can carry either voice or data, depending on the system design. The two time slots are called Time Slot 1 (TS1) and Time Slot 2 (TS2).

TDMA

For the amateur, this means one repeater allows two separate channels at the same time. Currently, most amateur DMR repeater systems 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.

 

TDMA Structure


Scalable Connectivity - A Closer Look

Scalable

Scalable programming. Reliable communications.

With DMR, you could choose to operate locally, using simplex, or a repeater using the Local talk group, which is similar to the way we use analog repeaters. From there, however, DMR provides many more options as far as scalability. Choose a Regional talk group for access to repeaters across several states, a National talk group, to access repeaters across the country, or even Worldwide!


Regional Talk Groups

Regional Talk Groups


New England Talk Groups (available on most NE repeaters)

Talk Group

Local
Connecticut Statewide (SNE)
Maine Statewide
Massachusetts Statewide
New Hampshire Statewide
Rhode Island Statewide
Vermont Statewide

New England
Region North
Northeast
North America (NA)
World Wide English (WWE)
World Wide Calling (WW)
TAC310
NE TAC 1
NE TAC 2
Parrot
DMR+ USA (Dongle Access)
DMR+ UK
(Dongle Access)
DMR+ Pacific (Dongle Access)
DMR to Allstar (RGRN repeaters)
ID

9
3109
3123
3125
3133
3144
3150
3181
8
3172
3
13
1
310
8801
8802
9998
133
143
153
3167
Time Slot

TS2
TS2
TS2
TS2
TS2
TS2
TS2
TS2

TS2
TS1

TS1
TS1
TS1
TS1
TS1
TS2
TS1
TS1
TS1
TS1
TS2

Click here for a list of Brandmeister Talk Groups


DMR Repeaters (Maine, New Hampshire, and Vermont) 

Call Sign

KQ1L
N1XBM
K1YFY
W1LH
K1XI
KB1UAS
N1UGR
N1ME
W1EMA
KC1FRJ
N1ITR
W1BHR
W1IMD
K1DQ
KQ1L
N1IPA
KQ1L
K1QVC
K1OX
K1OX
K1LTM
K1LTM
K1LTM
K1JC
W1IMD
W1WNS
W1MWV
KM3T
W1RCF
K1MOT
K1MOT
K1RE
K1RE
WA1ZYX
NN1PA
W1UWS
N1GBB
W1IMD
W1IMD
N1XBM
N1XBM
Location

Augusta
Bath
Buckfield
Calais
Camden
Corinna
Dresden
Holden
Knox
Lincoln
Litchfield
New Sharon
Portland
Shapleigh
Sidney
Topsham
Waterville
Derry
Chester
Bow
Rochester
Wakefield
West Ossipee
Sanbornton
Mt. Washington
Madbury
North Conway
Mt. Uncacoonuc
Mt. Uncanoonuc
Hudson
Hudson
Gilford
Gilford
Keene
Goffstown
Mt. Ascutney
Mt. Snow
Williamstown
Pico Peak
West Bath
Falmouth
State

ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
ME
NH
NH
NH
NH
MA
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
VT
VT
VT
VT
ME
ME
Frequency

145.170 -
449.775 -
145.320 -
147.045 +
145.370 -
145.220 -
145.430 -
145.310 -
145.420 -
145.350 -
146.700 -
145.140 -
145.340 -
145.110 -
145.240 -
145.190
146.925 -
145.310 -
145.190 -
145.170 -
145.240 -
145.280 -
147.075 +
145.180 -
145.120 -
145.180 -
448.775 -
444.300 +
145.220 -
145.260 -
447.725 -
145.360 -
449.425 -
444.650 +
145.200 -
448.475 -
446.275 -
448.875 -
444.500 +
449.775 -
448.825 -
Color Code

12
1
12
1
12
12
12
10
12
12
12
11
12
4
12
13
12
1
9
8
3
7
6
6
0
5
2
10
11
5
1
3
3
1
2
5
6
7
1
1
1
Netwok

NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
NEDECN
EWARN
NEDECN
NEDECN
NEDECN
NEDECN
RGRN
RGRN

Click here for the most current repeater listing, and to find out more about new repeater sites



Digital Voice - The Basics

Almost all of us use DV mode virtually every day of our lives. In fact, to many, it is their life! Mobile phones use advanced digital voice modes and the older 2G networks use a version of TDMA very similar to our own. All digital voice standards use encode/decode software called "codecs," which can be proprietary, as in the case of D-STAR, or open source, as in the case of DMR. DMR uses a form of FSK or "frequency shift keying" known as C4FM four level FSK constant envelope modulation. The voice is encoded/modulated, transmitted as a stream of data, then decoded by the receiver. The advantages of DV include easy IP distribution, excellent bandwidth efficiency and high quality audio. DMR applies a channel access protocol known as "Time Division Multiple Access" to allow two timeslots or voice channels within a single 12.5 kHz frequency allocation. Conveniently, the timing alogorithm for this is controlled by the repeater but the latest Motorola radios such as the 4000 series can also provide the facility - Timeslots and Talkgropus - Issue 2 February 2014 - Newsletter of DMR-UK & Yorkshire DMR Group.


First Steps – Registration

Go to the DMR-MARC website and follow the on-screen instructions.

Although it says “User” registration, it is possible to have more than one ID, (but this is not recommended).

A mobile and a base station, for example, could have the same ID as long as they are not transmitting on the same Time Slot and Talk Group at the same time. This is also where you would register a repeater on the DMR network.

Next: Get a Radio!

Manufacturers include: Hytera, Motorola, Kenwood, Vertex Standard, Icom, Connect Systems, Tytera, and more!

CS580   Motorola   CS750

Click here to download a code plug for the Connect Systems CS801 (WS1EC channels)

Click here to download the programming chart for the Connect Systems CS801 (WS1EC channels)

Click here to download the WSSM Intro to DMR presentation



For more information:

DMR MARC
DMR MARC Worldwide Network
NEDECN
New England Digital Emergency Communications Network




Maine c-Bridge Net Watch (Live Network Activity)





  

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Wireless Society of Southern Maine, P.O. Box 6833, Scarborough, ME 04074