Don't conflate "DMR" with the internet component / ability of DMR.


A DMR repeater can function just like any analogue repeater.  Receiving and rebroadcasting radio transmissions to the local area - except that it's doing DMR instead of analogue.


Actually, DMR enables some interesting modes.  Such as a single frequency repeater.  DMR is a TDMA with two timeslots on a freq.  So it's possible to set up the repeater to "listen" on Timeslot1, and transmit on Timeslot2.  

And to point out the obvious, that means no big duplexer cavities.  No special hardware.  Nothing.  A simple handheld radio can (with appropriate firmware programming by the mfg) become a repeater.

DMR is cool stuff and is possibly the most useful mode for setting up controlled ad-hoc radio nets within a small geographic area.

those pics make me wanna take a VAC day right now and go buy another dirt bike

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You are too old Francis.

I'm late to the party but that's okay. DMR is an interesting topic as you will have grossly varying opinions both from amateur radio operators and professional technicians and I've already seen few comments from other professional technicians in here. DMR is fairly ubiquitous world wide (as it is the most widely adopted digital standard).

A couple of things to note about DMR.

• It is not uncommon to get better coverage with digital compared to analog. This has more to do with most radios being much more sensitive to digital modulation than analog modulation. As an example, my first generation Motorola XPR6550 will hit 12 dB SINAD around -119 dBm (0.25 µV for those still stuck on that reference) but would hit 5% BER at -122 dBm (or 0.18 µV). That can lead to a significant (30% or greater) coverage increase in a real world usable application.


• The power output of a TDMA radio isn't what it's actually outputting. This one is simple physics. Power is a rate defined by time (energy divided by time). Key a 4W radio for 2 seconds in regular FM, you've transmitted 8 Joules of energy (FM is measured in average power, not peak power). Key the same radio operating in DMR for 2 seconds (at the same power setting)...you've only transmitted 3.2 Joules of energy (or 1.8W) and peak power will also only show about 3W. This is simply due to the fact DMR radios only transmit for 27 ms out of every 60 ms.


• As @SnowMule said, just because it's IP doesn't mean the internet is used. Now, 95% of the amateur DMR systems out there either have direct internet access or are locally NATed to the internet. That's completely on the amateurs who built those systems. Thousands of commercial systems use IP over owned or leased paths without issues (dynamic routing protocols are also typically deployed for redundancy) including many public safety systems.


• Just because network connectivity is require for linking doesn't mean the repeaters fail to operate as standalone repeaters without a network connection.

I'll also add, I haven't used a DMR radio for amateur application in 5 years. Amateur DMR grew too quickly in a not very well planned and thought out way. I can honestly say, it was great back in the days of DMR-MARC and really only radio techs had the radios because the networks were smaller and better thought out (not overloaded with talk groups and busy timeslots).

Yes, my studies indicate increased battery life due to lower power output IS an advantage to rx/tx in digital mode.

And I do understand that digital repeaters work standalone with digital radios just like the analog setup, internet notwithstanding.

The fact that a digital repeater does not require a big duplexer is interesting.

One would think that digital in general then would become the way of things, over time, wouldn't it?

Just to be clear - All DMR is digital.  Not all digital is DMR.  When we refer to "DMR" we mean a specific digital protocol originally developed and branded by Motorola as Mototrbo.  (or something like that, the pros can clarify)

Yaesu's fusion is digital.  It is not DMR.  Nor is it possible to do a single freq repeater on Fusion* as fusion is not split by time, instead opting to fit the entire digital signal within half the bandwidth instead of half the time as DMR does.


*I feel like i need to go ahead and caveat here before someone comes in and does it for me.  We aren't talking about parrot repeaters.  True, honest to goodness effectively real-time repeaters.**


**And for the real pedantist, yes we understand a single freq DMR repeater could be described as a parrot repeater turning on and off every 30 milliseconds.  Thanks.  

It already is. It is analog FM that is dying, or mostly dead, outside amateur use. The competing digital protocols are resulting confusion/hesitance and interoperability obstacles are probably the biggest things keeping analog alive.

A good way to see what is going on in your area without making much of an investment and commitment is:

SDR Dongle
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SDR #
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DSD Plus