1. What is this thing called DMR ?

2. Digital Mobile Radio Where did DMR come from and who developed it?
Digital Mobile Radio (DMR) was developed by the European Telecommunications Standards Institute (ETSI). It is used worldworld wide in the professional field.
It is broken up into three tiers, Tier I, II & III.

3. Tier II Three Tiers (Tier I, II & III)
Amateur Radio users follows Tier II.
Tier II is a 2-slot TDMA 12.5 kHz wide peer-to-peer and repeater mode specification, resulting in a spectrum efficiency of 6.25 kHz per channel.
Each Time Slot can be either voice and/or data depending upon system needs. Data is up to the repeater owner.

4. TDMA & Time Slots TDMA also know as Time Division Multiple Access.
In short term, it takes our frequency and divides it in two so that we can have multiple access on a single channel.
Once divided into two segments we have what they call Time Slots.
FM Analog bandwidth is 25 khz wide.
DMR is Narrow Band and 12.5 khz wide.
When it divides the channel it then becomes 6.25 khz and we then can have two stations carrying on a conversation on the same channel.

5. DMR only uses 25% of the bandwidth per talk channel
DMR only uses 25% of the bandwidth per talk channel. Each channel can carry either voice
and/or data depending on system design. The two time slots are called Time Slot 1 (TS1) and Time Slot 2 (TS2).
fc fc fc fc – 6.25 fc fc
Analog FM is Wideband 25 kHz Channel Bandwidth.
DMR is Narrowband 12.5 khz (6.25 kHz per Channel per TS1 & TS2).

6. Just a quick note on DMR & battery life….
The utilization of TDMA offers about a 40% battery savings on transmit, extending talking time over non-TDMA and analog transmissions for portable users.

7. DMR Terminology….. Talkgroups - Also known as channels.
Zones – Grouped talkgroups or channels.
Color Codes – Like analog CTCSS or DCS.
Times Slots – Channel sharing, TDMA.
Code Plugs – A radio configuration.
Static – Talkgroups are “always on”
Dynamic – Talkgroups are access by PTT.

8. Talk Groups (TG) are a way for groups of users to share a time slot (one to-many) without distracting and disrupting other users of the time slot. It should be noted that only one Talk Group can be using a time slot at a time.
Check with your local repeater operator to find out what Talk Groups/Time Slots are available on a repeater.
Zones - DMR radios support Zones. A Zone is just a grouping of individual channels. Some model radios may limit the number of channels per Zone and the number of Zones allowed, i.e. 256 zones and 16 or 64 channels per zone.

9. Color Codes -DMR repeaters use Color Codes (CC) much like analog repeaters use CTCSS (PL) or DCS. To access a repeater you must program your radio to use the same CC as the repeater. There are 16 different CCs (CC0-CC15).
The use of Color Codes is not optional on DMR systems. If your Color Code is not set correctly, you will not be able to access the repeater. The only real purpose of using different Color Codes is when multiple repeaters operating on the same frequency have overlapping coverage areas.

10. Static
On the BrandMeister network static talkgroups are configured by repeater operators. These Talkgroups are similar to “always­on” talkgroups. They will always transmit when there is traffic. These are the only talkgroups that must be configured by repeater operators.
Dynamic
When a user keys up on a dynamic talkgroup the BrandMeister system creates a subscription for that talkgroup on that repeater. Then, for 15 minutes, the system will send audio for that talkgroup to the repeater. 15 minutes after the last transmission on a given repeater, that talkgroup will be dropped from the repeater.

11. DMR Simplex operation….
For simplex traffic, the accepted standard in the DMR amateur community is to use TG99 on TS1 with CC1.
Standard DMR simplex frequencies…..
UHF , , and
VHF and
The DMR community asks that we do not use the national simplex channels for DMR simplex operation, i.e and

12. When you make an initial transmission to announce your availability, to place a call to another station, or to make a general call, you should also announce what Talk Group you are on because some users may be scanning or have radios without a display.
Examples of good operating practice for initial calls on the DMR networks include:
“This is WW8AAA monitoring UHF Local.”
“WW8AAA this is KX8XYZ on Ohio Statewide.”
Please avoid calling CQ; DMR is not HF and operating DMR over the network is not DXing.

13. DMR Informational Links…..

14. AC8GI Repeater….
This is a BrandMeister (BM) repeater system. Otherwords it is connected to the BM network.
VHF – / Mhz.
Motorola 8400 / 40 watts
UHF – / Mhz.
Motorola 8400 / 100 watts
Both repeaters use Color Code (CC) 7.
All Talkkgroups (TG) use Timeslot (TS) 1.
The only Talkgroup (TG) that uses Timeslot (TS) 2 is the N8OJ Link in Marietta Ohio.
Any TG that is listed on the BrandMeister Talkgroup list can be used on these repeaters, but only on Timeslot 1.

15. Thank you for your time and I hope to talk with you on DMR!
Scott Long, K8SM
Monitor : Ohio Statewide (TG3139), UHF Local (TG313985), VHF Local (TG313982), N8YMT Fusion Link (TG31399)
Thank you for your time and I hope to talk with you on DMR!
73’s Scott, K8SM
I want to take this opportunity to give credit and thanks to those who have provided information for the DMR community, W2XAB, N5QM, ARRL and others.