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 LARCH W. HILLS HEBO GOAT MTH PRAIRIE GRAY BUTTE
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