or Digital Mobile Radio,
is an Open Standard digital voice and data mode defined by the European
Standards Institute (ETSI), and is used in commercial and amateur
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, DMR offers:
- Affordable digital systems
with low complexity.
- Products that are available in
regions of the world.
DMR protocol covers:
- Unlicensed (Tier I)
- Licensed Conventional (Tier II)
- Licensed Trunked (Tier II)
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.
Standards, and an Open Philosophy.
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
In 2009, members established the DMR
Association to further advance the standard and to maintain
Formal testing has been taking place since
DMR and Ham Radio
- All-digital network of over
400 repeaters in 37 countries.
- More than 10,000 registered
- Repeaters are connected ALL
- 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
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.
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).
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.
Connectivity - A Closer Look
Scalable programming. Reliable
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!
England DMR Talk Groups (available on most NE repeaters)
Connecticut Statewide (SNE)
Rhode Island Statewide
New England Wide
North America (NA)
World Wide English (WWE)
World Wide Calling (WW)
DMR+ USA (Dongle Access)
DMR+ UK (Dongle
DMR+ Pacific (Dongle
Local - Single Site Only
Coos County, NH
Cape Cod, MA
Connecticut, Eastern LI, NY QSOs
New Hampshire QSOs
Rhode Island QSOs
New England Wide + NB
Northern New England
New England TAC 2
New England + NY, NJ & PA
North America (U.S. & Canada)
World Wide English
World Wide (All Languages)
TAC 310 (a reflector)
TAC 311 (a reflector)
SKYWARN Activations and Nets
New England TAC 1
User Activated English 1
User Activated English 2
Listen to your own audio
DMR + UK
DMR + Pacific
Click here for a list of NEDECN Talk Groups
Click here for a list of
Brandmeister Talk Groups
(Maine, New Hampshire, and Vermont)
here for the most current repeater listing, and to find out
new repeater sites
Digital Voice -
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 –
to the DMR-MARC website and follow the
Although it says “User” registration, it
is possible to have more than one ID, (but this is not recommended).
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.
Get a Radio!
Manufacturers include: Hytera, Motorola, Kenwood, Vertex Standard,
Icom, Connect Systems, Tytera, and more!
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 a code plug for the Connect Systems CS800D (dual band mobile)
Click here to download the WSSM Intro to DMR
DMR MARC Worldwide Network
New England Digital Emergency Communications Network
DMR Simplex Sunday
Sunday, June 17, 2018, WSSM members set out on a coordinated mountain
topping expedition in order to learn more about the range limits of DMR
simplex. The longest distance contact achieved was between Mt.
Equinox, VT and Saint-Jean-Sur-Richelieu, QC - a distance of: 151.13 mi / 243.22
km (UHF), and the second longest was between Mt. Greylock, MA and Mt.
Washington, NH - a distance of: 145.56
mi / 234.25 km (both VHF and UHF).
here to read the whole story.
Here's a list of some of the nets that take place on various Talk Groups around New England:
– The National Weather Service in Gray, ME will periodically ask for
weather reports and observations on the SKYWARN (759) Talk Group.
If during the weather event, any observers have a significant report,
such as a funnel cloud, or trees down, please call in on SKYWARN TG
759. In the event of multiple weather activities by Gray, Norton,
Burlington or Albany NWS offices, communications will shift to
Statewide Talk Groups as appropriate (ME, NH, MA, RI, VT, etc.).
- Sundays at 8 – 9 PM is the Providence Radio Association (PRA) Net on NETAC1 TG (8801)
- Mondays at 8 – 9 PM is the New England DMR Net on New England Wide TG (3181). Good discussion of Tech Topics and New England Amateur Radio Events.
- Mondays at 9 – 9:30 PM is the New England Digital Swap Net. List your FOR SALE and WANTED TO BUY Items.
- Tuesdays at 8 – 9 PM is the Vermont State DMR Net on VT SW TG (3150)
- Wednesdays at 8 – 9 PM is the YCCC Contesting and DX Net on NETAC1 TG (8801)
- Thursdays at 8 – 9 PM is the New Hampshire State DMR Net on NH SW TG (3133)
(Live Network Activity)