What is DMR?

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KeithBogut

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I've seen a lot of posts about paying for an upgrade to DMR. I read the RR glossary description, but (to me) it reads like gibberish.
What is DMR?
What would I be able to do after installing it that I can't do now?
 

jonwienke

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Do you even google, bro?

It's a common digital radio protocol.

If you install the upgrade you'll hear voice instead of digital static when DMR transmissions are received.
 

n5ims

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It's a digital audio mode used by generally smaller agencies and businesses. Also it's getting popular in the ham world. Perhaps the best known brand name for it is MotoTRBO by Motorola. It is a published standard so compatibility between different companies products is generally easy to accomplish (so long as you don't get sucked into the proprietary extensions that the salesmen always push to force you to be stuck with only their products). As far as scanners go, the upgrades should handle most any DMR system in the database. As usual, any encrypted signals will still not be monitorable.

There are two standard tiers:

* Tier 1 is the lowest end and is basically just an upgrade from radio to radio analog to make it digital, although some special features such as GPS positioning can be active. This is used only in the lowest end situations, such as in a school where a teacher in the pick-up line can call for a student that's still in the building so the walkie-talkie equipped teachers can locate the child and get them out to their ride.

* Tier 2 is the more popular and more useful mode. It typically uses a repeater and can provide two separate and independent talk paths on a single repeater pair. The radios send quick pulses of data on their assigned time slot and all radios will only listen to their assigned time slot so there is no interference between the two independent conversations.

* Tier 3 is basically just an extension to tier 2 that adds trunking into the mix. Basically that extends the two "channels" that are fixed use in standard tier 2 to allow different uses for an available "channel". You're still limited to two active "channels" per repeater, but using the trunking feature, a channel can be for the maintenance crew one second and for the security team the next. A system can be further extended by adding additional repeaters to increase this 2 "channel" maximum to be 2 "channels" per repeater in the system. Often the additional repeater functionality is one of those proprietary extensions.
 

raisindot

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Let me ask another newb type question about this, since I have a HP436. I used that frequency search list above and see that there are around 1,000 DMR "licenses" in my county, concentrated in a few narrow frequency ranges. Since I don't know what the range of these things are, if I enter some of these frequency ranges into a search, will I "hear" the "digital static" on a received frequency that will clue me that this is a DMR "catch"? Just want to get a sense of how many "unencrypted" DMR frequencies I might be able to receive from my location.
 

AggieCon

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If you are simply playing a DMR frequency as plain analog FM demodulation, you will hear the "digital buzz" of the data stream. While there might be some sort of small variation a trained ear might be able to detect between encrypted and open, I think it's going to sound pretty much the same.

Encryption doesn't seem to be that prevalent with DMR.
 

marksmith

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Try some of the frequencies listed. I noted that some of the Licensee and frequencies shown in the DMR search are actually currently using straight analog FM that does not require the DMR upgrade.

Maybe they have licensed the frequencies to upgrade to DMR protocol and just have not done so yet.

Mark
536/436/WS1095/HP1/HP2/996T/996XT/996P2/396XT/325P2/PSR800/15X/others
 

raisindot

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Thanks for the responses. I actually didn't mean "encrypted," I really meant to say whether I would be able to hear the "digital static" using whatever modulation that might tell me if DMR is being used. I would assume that if I can "hear" a voice transmission on any of these frequencies it's not DMR. :)
 

jonwienke

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If you get the DMR upgrade key, you will hear voice, with an indicator in the bottom-right of the screen indicating what flavor of DMR.
 

AggieCon

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Thanks for the responses. I actually didn't mean "encrypted," I really meant to say whether I would be able to hear the "digital static" using whatever modulation that might tell me if DMR is being used. I would assume that if I can "hear" a voice transmission on any of these frequencies it's not DMR. :)
Yes, that method is very smart. I did the same before upgrading. And also for NXDN.

Keep in mind there is a small possibility (but I've never seen it) that it is digital and something other than DMR.
 

jhampton2000

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If you are simply playing a DMR frequency as plain analog FM demodulation, you will hear the "digital buzz" of the data stream. While there might be some sort of small variation a trained ear might be able to detect between encrypted and open, I think it's going to sound pretty much the same.

Encryption doesn't seem to be that prevalent with DMR.
To confirm, you won't be able to hear the difference between an encrypted and non-encrypted raw DMR data stream...same goes for NXDN.
 
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