Digital Mobile RadioAN INTRODUCTION

BOB STEPHENS AF9W

January 27, 2019

PSRG Annual Meeting

DIGITAL MOBILE RADIO

• Commonly Known as “DMR”

• A Standard for Digital Voice Communications

• Published by the European Telecommunications Standards

Institute (ETSI) in 2005 (Tier 1 & Tier 2) | 2015

• The goal of the standard is to create a digital system that is:

• Low Cost

• Low Complexity

• Interoperable Between Vendors

THREE TIERS

• Tier I - Unlicensed

• Tier II - Conventional, direct or repeater, non-trunked

• Tier III - Trunked

Amateur

Radio Use

BANDWIDTH COMPARISON

DIGITAL VOICE CHANNEL DEFINITION

• FDMA (Frequency Division Multiple Access) for P25 Phase I &

NXDN™

• TDMA (Time Division Multiple Access) for P25 Phase II & DMR.

• The basic difference between FDMA and TDMA is the

definition of a channel and how it is used.

FDMA CHANNELA particular bandwidth (e.g.

12.5 kHz) at a particular

frequency (e.g. 150.000

MHz) is used to define an RF

channel.

TDMA CHANNEL

• 12.5kHz channel

bandwidth is

maintained

• Time sharing allows

two 6.25kHz voice

channels to share the

12.5kHz bandwidth

DMR TDMA INFRASTRUCTURE

DMR LINKING

POPULAR DMR NETWORKS

• IPSC and cBridge

• Based on Motorola IPSC and cBridge

• Central Server Architecture

• Admin defined talkgroup structure

• Original DMR-MARC amateur network and PNW DMR

• Brandmeister – Amateur Radio DMR Network

• Created in Europe by telecom experts

• Distributed Server Architecture

• User Defined talkgroup structure

IPSC / CBRIDGE LINKINGDMR A

Repeater 1

DMR A

Repeater 2

DMR A

Repeater 3

DMR A Master

DMR B Master

DMR B

Repeater 1

DMR B

Repeater 2

DMR B

Repeater 3

DMR C

Repeater 1

DMR C

Repeater 2

DMR

Repeater 3

DMR D

Repeater 1

DMR D

Repeater 2

DMR D

Repeater 3

DMR C Master

DMR D Master

US

National

cBridge

State cBridge State cBridge

European

cBridge

IPSC / CBRIDGE LINKINGDMR A

Repeater 1

DMR A

Repeater 2

DMR A

Repeater 3

DMR A Master

DMR B Master

DMR B

Repeater 1

DMR B

Repeater 2

DMR B

Repeater 3

DMR C

Repeater 1

DMR C

Repeater 2

DMR

Repeater 3

DMR D

Repeater 1

DMR D

Repeater 2

DMR D

Repeater 3

DMR C Master

DMR D Master

US

National

cBridge

State cBridge State cBridge

European

cBridge

Linking structure defined by talkgroup

definitions in cBridge

IPSC / CBRIDGE LINKINGDMR A

Repeater 1

DMR A

Repeater 2

DMR A

Repeater 3

DMR A Master

DMR B Master

DMR B

Repeater 1

DMR B

Repeater 2

DMR B

Repeater 3

DMR C

Repeater 1

DMR C

Repeater 2

DMR

Repeater 3

DMR D

Repeater 1

DMR D

Repeater 2

DMR D

Repeater 3

DMR C Master

DMR D Master

US

National

cBridge

State cBridge State cBridge

European

cBridge

All Repeaters

Connected to the Same Talkgroup

Key Up Together

DMR DEFINITIONS

RADIO ID

• A unique 7 digit decimal ID number allocated per user

• Usually only 1 ID per user

• Users should have Radio ID for each radio in simultaneous use

• Assigned by www.radioid.net

• Unlike D-Star, you cannot use your callsign as your Radio

ID

• Must vocally ID as on any other analog channel.

TALKGROUP

• A Virtual Radio Channel normally defined by geographic

region, language, special interest, etc.

• Think of talkgroups as a complicated tone squelch

• Talkgroups are assigned to repeaters by the repeater

owner

• Hundreds of talkgroups are currently assigned

TALKGROUPS AND REPEATERS

TIMESLOT 1Talkgroup Number Pseudonym

1 World Wide

3 US / English

TIMESLOT 2Talkgroup Number Pseudonym

2 Local Only

3100 DCI Bridge

3176 Southwest US Region

310 TAC 310

Repeater

Ch 1 TS1 TG 1

Ch 2 TS2 TG 2

Ch 3 TS2 TG 3176

Ch 1 TS1 TG 1

Ch 2 TS1 TG 3

Ch 3 TS2 TG 3176

TALKGROUPS AND REPEATERS

TIMESLOT 1Talkgroup Number Pseudonym

1 World Wide

3 US / English

TIMESLOT 2Talkgroup Number Pseudonym

2 Local Only

3100 DCI Bridge

3176 Southwest US Region

310 TAC 310

RepeaterTS1 TG 3176 TS1 TG 3176

Ch 1 TS1 TG 1

Ch 2 TS2 TG 2

Ch 3 TS2 TG 3176

Ch 1 TS1 TG 1

Ch 2 TS1 TG 3

Ch 3 TS2 TG 3176

• Radio 1 Transmits on Ch 3

• Radio 2 hears voice on Ch 3

TALKGROUPS AND REPEATERS

TIMESLOT 1Talkgroup Number Pseudonym

1 World Wide

3 US / English

TIMESLOT 2Talkgroup Number Pseudonym

2 Local Only

3100 DCI Bridge

3176 Southwest US Region

310 TAC 310

RepeaterTS1 TG 1 TS1 TG 1

Ch 1 TS1 TG 1

Ch 2 TS2 TG 2

Ch 3 TS2 TG 3176

Ch 1 TS1 TG 3

Ch 2 TS2 TG 2

Ch 3 TS2 TG 3176

• Radio 1 Transmits on Ch 1

• Radio 2 hears nothing, only

channel busy indicator

TWO TYPES OF TALKGROUPS

Static – Full-Time (FT) - Always On• Always transmitted by repeaters

• Mainly talkgroups of primary use by repeater users

Dynamic – Part-Time (PT) - User Activated• Only heard on repeater when activated by user

• Activated by pressing PTT (kerchunking) on TG

• Usually will time-out after a defined period of no localactivity

• Secondary little used talkgroups

LOCAL TALKGROUPS

RepeaterLocal 1 or Local 2 Local 1 or Local 2

WASHINGTON TALKGROUPS

Washington 1

Washington 2

Cascades East 1

Washington 1

Washington 2

Oregon 1

Oregon 2

Idaho 1

BC 1 PNW 1

PNW 2

PNW REGIONAL TALKGROUPS

TACTICAL TALKGROUPS

• Allows conversations between repeaters where talkgroup is PTT

• Only PTT repeaters are affected

CHANNEL• Defined by

Repeater transmit frequency

Repeater receive frequency

Color Code (CC)

• a number from 1 – 15 identifying

repeaters on the same frequency in

overlapping areas - like a CTCSS tone

only digital

Talk Group

Time Slot

• Usually assigned a name for

reference

• Each talk group on a repeater is

represented in the radio by a channel

Name RX Freq TX Freq CC TG TS

Cougar WASH 1 441.288 446.288 1 WASH 1 1

Cougar WASH 2 441.288 446.288 1 WASH 2 2

Cougar PNW 1 441.288 446.288 1 PNW 1 1

Cougar PNW 2 441.288 446.288 1 PNW 2 2

Gold WASH 1 440.7 445.7 1 WASH 1 1

Gold WASH 2 440.7 445.7 1 WASH 2 2

Gold PNW 1 440.7 445.7 1 PNW 1 1

Gold PNW 2 440.7 445.7 1 PNW 2 2

ZONE

• Logical grouping of channels within a radio codeplug

Zone Name RX Freq TX Freq CC TG TS

Cougar Cougar WASH 1 441.288 446.288 1 WASH 1 1

Cougar WASH 2 441.288 446.288 1 WASH 2 2

Cougar PNW 1 441.288 446.288 1 PNW 1 1

Cougar PNW 2 441.288 446.288 1 PNW 2 2

Gold Gold WASH 1 440.7 445.7 1 WASH 1 1

Gold WASH 2 440.7 445.7 1 WASH 2 2

Gold PNW 1 440.7 445.7 1 PNW 1 1

Gold PNW 2 440.7 445.7 1 PNW 2 2

DIGITAL CONTACT LIST• List of all DMR Radio ID with associated amateur callsign

• Loaded into radio to provide function similar to Caller ID

• Maximum caller ID count per radio varies by radio model

CODEPLUG

• Represents the radio programming

• Originally codeplugs were memory modules programmed outside of radio and

plugged into radio

• Created with a CPS (Customer Programming Software)

• Contains channels, zones, talkgroups, scan lists, digital contact list, etc

• Can be shared but Radio ID must be changed for each operator

• The tedious part of DMR

ANYTONE D868UV CPS

WHY SHOULD YOU CARE ABOUT DMR

DIGITAL VOICE MODES USED IN AMATEUR RADIO INTERCONNECTED SYSTEMS

# of Repeaters System Type

1,454 DMR

1,157 D-Star

1,669/384 Fusion/Wires-X*

318 P25

97 NXDN

* Notes

• 1,669 System Fusion repeaters are reported but

only 384 are listed as connected

• As our focus is on U.S. and Canada, the TETRA

European format is not included.

• As Repeater Book allows user self-maintenance, its

accuracy is always suspect.

Repeaters in service as reported by RepeaterBook.com on 8/6/2018 @ 16:00 PDT

for the U.S. and Canada.

DIGITAL ADVANTAGES

• Less bandwidth than AM, FM, SSB

• Better signal quality at lower signal levels,

• However,

> Levels must be above a threshold where decode is possible

> Multi-path impacts reception more than on analog FM

• Digital data is easy to route over the TCP/IP for repeater

networking

DIGITAL ADVANTAGE

Analog versus Digital Signal Attenuation Over Distance

DMR RADIOSMultiple Manufacturers

• Commercial

• Amateur Centric

Part 90 Certified

Prices start at $89 for UHF only HT -

$139 for VHF/UHF HT

Very popular radio – Anytone

D878UV VHF/UHF HT is $219

Most Popular Amateur Centric Radios

Commercial Radios

Motorola

Hytera

Vertex

Connec

t

System

s

TYT Radioddity

DMR IN THE PACIFIC NORTHWEST

PACIFIC NORTHWEST DMR –WA7DMR

• A system of open use DMR repeaters located in the Pacific

Northwest

• The PNW c-Bridge currently supports 40 plus MotoTRBO

repeaters with 25 plus in Washington, 10 in Oregon and 1 in

Idaho

• Has several c-Bridges, an echo server and 8 MMDVM servers

for additional repeater and Hotspot support

• Where possible, repeaters are IP linked via HamWAN

PNW DMR REPEATER NETWORK

PNW DMR COVERAGE

2017-11-14

DMR FOR EMCOMM – DEDICATED TALKGROUPS

• Two PNW talkgroups are

reserved for EMCOMM

• PS 1 is FT with 120 minutes of

hold-off

• PS 2 is PTT for 60 minutes

connect time and with 60 minutes

of hold-off time

• Currently supported on almost all

Western WA repeaters

DMR FOR EMCOMM – LOCAL EVENT SUPPORT

• Local 1 and Local 2 can be used for local events requiring only 1 repeater

• No reconfiguration of the system required, i.e. no linking or unlinking of repeaters

• With advance notice, special talkgroup arrangements can be made for regional

support

• Standard talkgroup structure supports regional communications

• Washington 1 & 2 for WA only

• Oregon 1 & 2 for OR only

• PNW 1 & 2 for entire PNW region

• TAC channels available for background discussions

DMR FOR EMCOMM - RESILIENCY

• PNW DMR aims to create a resilient network without

dependency on commercial IP or power

• Larch, Baw Faw, Capital Peak, Baldi and Gold PNW DMR

repeaters interconnected with HAMWAN reducing

dependency on commercial IP – more repeaters in the works

• Many PNW DMR repeaters have backup power available

OREGON DMR NETWORK HAS DIFFERENT RULES…

• The Oregon DMR network has an operational philosophy different

than the rest of the PNW DMR system

• The Oregon DMR repeaters were set up to support Search and

Rescue and other Emergency Communications. Rag-chewing and

“chat-line” conversations are not allowed. Usage is limited to 5-10

minutes.

• This also includes the Megler and Larch Mtn sites (both in WA, but

controlled by Oregon managers).

• Refer to the OR North DMR Users Guide:

• http://www.trbo.org/pnw/oregon/DMR-user-guide-KB7APU.docx

DMR BEST PRACTICES

YOU AND YOUR RADIO

• Use High Power unless you know you have a clear signal

into the repeater

• Prevents BER and Signal Loss

• Be mindful of your audio

• No AGC on many DMR radios

• Check your audio using Parrot or online VU meter (coming soon)

• Cinderella audio is the best, not too hot and not too soft

SELECTING A TALKGROUP

• Select a talkgroup that covers the least number of repeaters

that allows you to accomplish your communication

• Two operators that can access the same repeater should use Local

channels

• Within a state, use a state talkgroup, i.e. Washington 1 or

Washington 2

• Timeslot 2 preferred; save timeslot 1 for priority traffic

• For long conversations, move to a TAC talkgroup

• Only ties up the repeaters at each end of the conversation

DMR OPERATING

• Wait a couple seconds for the system to come up so you won’t

chop the beginning of your conversation

• Wait between PTT to allows others to break in or unkey PTT

talkgroups

• Announce the talkgroup you are transmitting on

• Digital monitor and receive groups allow hearing transmissions on

multiple channels

• Operator may not be looking at their radio to see what talkgroup

you are transmitting on

PNW DMR KNOWLEDGE RESOURCES

• PNW DMR Website - http://pnwdigital.net/

• PNW Groups.io - https://dmr.groups.io/g/PNW

• Please join this group to keep abreast of network changes and status

• Good source for PNW DMR codeplugs

• PNW DMR Not-a-Net Gathering

• Each Wednesday @ 7:00pm PST/PDT

• Talkgroup Washington 2 (103153 on TS 2)

• Spring DMR Gathering at Valley Camp

• May 18th, 2019

• Watch PNW Groups.io for details