DMR in Amateur Radio

Stephen Brown - K1LNXJohnson City, TN

http://www.vol-net.net

So what is DMR?

• Digital mobile radio (DMR) is an open digital mobile radio standard defined by the European Telecommunications Standards Institute (ETSI) and used in commercial products around the world

So what is DMR?

• Digital mobile radio (DMR) is an open digital mobile radio standard defined by the European Telecommunications Standards Institute (ETSI) and used in commercial products around the world

• There are 3 "tiers" of DMR

So what is DMR?

DMR Tiers• Tier I is for license free use in the European 446 Mhz band

• This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power. There have been no commercial launches of DMR Tier I products to date.

DMR Tiers• Tier II covers licensed conventional radio systems, mobiles and portables. The ETSI

DMR Tier II standard is targeted at those users who need spectral efficiency, advanced voice features and integrated IP data services.

• All amateur networks have adopted and are using the Tier II standard

DMR Tiers• Tier III covers trunking operation.

• This standard is mainly meant for commercial use as "true" trunking is not allowed under Part 97 of the FCC rules

DMR Tier II• For Amateur Radio networks, the Tier II standard has been adopted and is in use

worldwide with several networks

• Occupies 12.5Khz of channel space and is a two "slot" TDMA based system that uses an AMBE+2 vocoder

• Two slots = two separate talk paths! Data is also usable on either timeslot, but voice is the primary function

DMR Tier II

• Each timeslot occupies 6.25 Khz of space for a total of 12.5 Khz of channel bandwidth

Talkgroups• Talkgroups are logical channels.

• They are numerically identified and alphanumerically identified in the radio’s codeplug

• Talkgroups work on a “group” calling principle, all radios set to receive a particular talk group will hear all activity

• All amateur repeaters are setup to use talkgroups, private calls are discouraged and disabled on most systems

Example talkgroups

The Network• There are currently 1,276 repeaters registered worldwide

• 672 repeaters are registered in the United States alone, this is over 50%!!!

• Network consists of several networks linked together

***not all of them are linked due to technical or political reasons

The NetworkMajor US based networks include:

NCPRN - http://www.ncprn.net

DCI - http://www.trbo.org

DMR-MARC - http://www.dmr-marc.net

The NetworkHow it all ties together

The Network• Each network has one or more servers running specialized software to

link repeaters and networks together

• For most networks here in the US this software is called a "C-Bridge" and is distributed by two companies

• Another popular software package is SmartPTT, we are currently investigating it's use for remote dispatch console capabilities

The Network

The Network

• Repeaters are linked together using a protocol called "IPSC" • "IPSC" stands for IP Site Connect and is a protocol that is proprietary to Motorola • Motorola does not license this technology to anyone but approved developers for

3rd party application development • Most DMR Amateur networks are using a Motorola infrastructure

Subscriber Equipment• Three major manufacturers

• Motorola

• Hytera

• Connect Systems - this is the cheapest and most popular option for hams

Subscriber Equipment• Motorola is best! (BUT I am incredibly biased!)

• Has the most complete feature set out of all, regular CPS and firmware updates (at a cost however)

• Is the most expensive option

Subscriber Equipment• Hytera is also a viable option, but programming software

is not as polished and contains bugs

• Radios have a solid quality feel however

*** DISCLAIMER: I have very little experience with this line

Subscriber Equipment• Connect Systems is the most "ham friendly" option

• Cheapest radio out there that is fully DMR compliant

• Software and firmware is free!

• Handhelds only at this time, mobile is development

VolNET - DMR in the state of Tennessee

• VolNET was formed in March of 2015 by myself, K1LNX, and Stuart Whitmire WB4JGI of Cleveland with the goal of promoting a statewide network in Tennessee

• We currently have 3 repeaters in operation on Bays Mountain, Knoxville, and Cleveland/Polk county

• A potential 4th repeater is planned for Sevier county soon

Demo

Questions?

Thank you! Links: http://www.vol-net.net - VolNET http://www.ncprn.net - our partner network

Manufacturers: http://www.motorolasolutions.com/en_us/products/two-way-radios/mototrbo.html http://www.hytera.us/Catalogs/Catalogs.aspx?id=1 http://www.connectsystems.com

73! Stephen K1LNX