KB7APU repeater system

MotoTRBO/Digital Mobile Radio

information.

How Field SAR Coms Work

How Repeaters Work

First DMR HAM radio system in the

State of Oregon

• What is DMR (Digital Mobile Radio) ?

• How to access it?

• Advantages

• Practical uses

• Key benefits DMR has in a search and

rescue environment?

Digital Mobile Radio

• 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[1] 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.

• 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.

• Time division multiple access (TDMA) is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity.

Audio Quality Comparison Analog radio transmission

Recording from UHF repeater

DMR contact

into Mt Hood

repeater 5 watt HT from Timothy Lake

UHF DMR

recording

USFS road 57 and 5720 with

a 45 watt mobile radio ¼ whip

antenna on roof.

Gray Butte

DMR repeater 45 watt mobile ¼ wave whip.

How to access DMR

• Get a DMR capable radio/DMR hotspot

• Any Motorola MotoTRBO UHF radio

• Connect systems CS750, CS800 mobile

• Hytera, Tytera, Vertex and many other brands

• Program it, understand how it works and

experience a new world of digital technology.

• Most DMR UHF radios are FCC type accepted

so they can be used on your team’s licensed

UHF frequencies.

Advantages

• Two conversations on one frequency at the

same time 2 timeslot TDMA.

• Multiple talk groups on both time slots.

• Local, regional and national radio traffic on the

digital network.

• Private calls, call another radio directly without

any other user hearing the conversation.

• All calls, paging, text messaging and more.

DMR hotspots, just need power,

IP connection and DMR radio

Talk group example

First HAM DMR radio network in

Oregon

• This is the first known DMR HAM radio

network specifically designed and

implemented for Search and Rescue

operations in the United States.

• In the SAR environment the DMR system

is used for SAR coordination between

SAR base, mobile relays in the field and

the in town coordinator (ITC).

KB7APU SYSTEM

The DMR HAM network is open to all

licensed HAM radio operators but users

must follow a user guide which outlines

how to use the system, how the users radios

should be programmed and that failure to

follow the simple guidelines will result in

training or retraining. DMR is much more

complicated than a standard repeater

system.

Practical uses

• Talk locally or around the world

• Digital audio quality

• Easy linking via IP

• All repeater sites use the same server so

they act as one repeater. If you talk on

Larch Local 1 you will be heard on all the

repeaters on our network on talk group

Local 1.

Use for search and rescue

operations

• By using several IP linked repeaters you

have better coverage in most cases.

• DMR format cannot be monitored by most scanners.

• SAR 1 and SAR 2 talk groups have priority and mute all other outside traffic for an hour after the last key up.

• Good quality digital audio, private and all call messages.

DMR coverage map

MEGLER

BUXTON

HEBO GOAT

LARCH

MTH

GRAY BUTTE

W. HILLS

PRAIRIE

Oregon DMR repeaters on the air

• West Hills 440.625+

• Larch Mtn WA 442.950+

• Government Camp 442.9875+

• Goat Mtn 442.750+

• Mt Hebo 442.8125+

• Gray Butte Redmond OR 442.950+

• Buxton Lookout 444.025+

• Megler Mtn WA 444.2375+

• Prairie Pk OR 442.9625+

Trbo.org

15:25:42.676

Sep 19 100.7

Seattle WA -

Cougar Mtn -

N7ERP

315309

KE0CO -

Brian -

Seattle WA

3153048

TAC 1-24 -85.2 DCI 0.5%

Goat Mtn DMR repeater

SLR8700 repeater/duplexer

Goat Mtn

Gray Butte DMR repeater

Redmond OR

Tower on Gray Butte

Prairie PK DMR repeater

Prairie PK

Mountain top repeater

maintenance in winter

Almost made it to the top

Snow cat trip to Larch

Repeater on a snow sled

Winter repeater maintenance

Rime ice on antenna and tower

So now what?

• How do we set up a system for our

region?

• How much does it cost?

• Who can we ask for technical assistance?

• Does your brain hurt?

• OTHER QUESTIONS?

• Loren Flindt-KB7APU morsnow@q.com