What is DMR?

DMR is a digital mode, DMR stands for: Digital Mobile Radio.

It’s a way (mode) of digitally sending voice and data to other stations.

Because I ‘m new to DMR, I need a lot of information, about all the terms and ways of use. It wasn’t easy to find everything I needed. But slowly I’m getting there. To help others, this page is created, I’m hoping that you will find what you are looking for.

Difference in signal

Analog

from: md5decrypt.netIf I may refer to analog, first you had CW (Morse code), “just” dots and strips to communicate. Later on, it was possible to send also voice in AM (sometimes also called double sideband), SSB (Single sideband, Lower (LSB) and Upper (USB) and FM.From: hamradioschool.com

A mobile radio has a limited range it can operate. let’s say for a 4 watt FM radio, you will a range of 15-25km (at most). After that, your signal will fade out.

When the other station is on the edge of your range, they still can hear you in the noise.

Digital

With a digital radio, your audio is (very) good, just like an FM radio. And it stays that way until you reach the edge a the radio’s range. But the range of digital is much higher than that of the analog signal.

Repeaters

From: http://qrznow.com/building-a-complete-ham-radio-repeater/To extend the range of analog and digital radio’s you can use a repeater. Which is basically a radio which only receives and then transmit through another radio. This principle is used for analog as well as digital. 

Both radio’s (left picture) can’t hear each other, because of the distance. But because the repeater is set up at a high point, it can reach both radios.

Terminologies

Every mode and technique has its own terms and ways of use. DMR is no exception.

I will describe some of the most used, Of course, this list can’t be complete, but it will grow over time:

TermExplanationnote
DMR-IDYou had to register yourself as a user of the DMR network, when you do, you will receive an ID. Which you can be identified with.
ChannelA channel is the information required for the repeater or simplex station. So here is the information about frequency, color code, time slot, etc.
TalkgroupA talkgroup is a collection of channels
TimeslotYou can see this as a filter. Normally (analog) you can use one frequency with 1 station sending at the time. This is no different with digital. There are two timeslots, 1 and 2. Now two stations can use 1 frequency at the time.
Hotspota mobile repeater for private use.
ReflectorA refelctor joins another network to a channel.
Contactsis a station (repeater, amateur, etc) which is stored in your contactlist
Color codeYou can see this as a CTCSS/DCS code. It works the same.