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What is DMR?

What is DMR?

 

 

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Transcript:

This is Sebastian KBØTTL, and today we're gonna do a brief introduction to the world of DMR. You're probably familiar with analog radio UHF and VHF. Talking on local repeaters, talking simplex to your friends a few miles away, just some changes with DMR technology is that instead of being able to carry on just one conversation on a repeater at a time. DMR now offers the capability to have two simultaneous conversations going on on the same repeater. So basically, in a nutshell, we're going to be using the internet in conjunction with the repeater, versus just using a stand-alone repeater. If you like our content here today, please make sure to hit that like button and subscribe to our YouTube channel.

So now for the first time in a long time, suppose you're in Chicago and you have a friend over in New York and you both have handhelds, you're both talking on repeaters. But before you could only talk on a repeater as far as that repeater would extend RF wise. But now, you'd be logged into a digital talk room while talking on the repeater. So say your friend in New York is also on that same digital talk group on his repeater, your now going to be able to talk back and forth. This enables a lot longer communications and a lot more privatized of communications and a lot more directed communications because you're going to be able to select which talk group you wished to talk on. There are thousands of talk groups available in DMR. So basically, if you're on say like a localized talk group, you'll be talking to people in your local or statewide area, you can go on nationwide talk groups or even worldwide talk groups and talk to people all over the world, just using a basic handheld radio either on a repeater or your own personalized hotspot. The operation of the radios, although similar in the analog realm, and yes DMR radios also work in the analog realm, as well as the digital realm. It's just basically a difference in programming and code plug. I'm going to go over a few of these differences right now over on the computer, so right now we're just going to step over to the computer and I'm going to show you just somewhat programming-wise and somewhat channel-wise how the channels and features differ between DMR and analog radio.

I remember back when I was first licensed back in 1995. A lot of us were just sitting around and we're wondering hey, are we ever gonna be able to hook these repeaters together on two meters, on four fortys so we can talk to our friends, say across the country or even across the globe. And back then the internet was still in its infancy so we didn't really have means by which to go ahead and do this. The answer to all of this is actually DMR or digital mobile radio. Instead of an analog signal, what we're now doing is we're now using a digital signal, we're actually putting two, or the capability for two digital signals within one frequency pair so that two simultaneous conversations can be taking place on the same repeater.

DMR uses narrowband versus wideband, that is a twelve and a half kilohertz band worth versus a twenty-five kilohertz band worth, like analog uses. What we're doing is we're actually dividing the digital signal up into time slots. This is in a blockchain type scenario, thirty-millisecond gaps in the transmit time so one block of thirty milliseconds is time slot one. The next block of thirty milliseconds is time slot two and so on. So with the new digital technology, we can now fit two conversations where one conversation once was. Basically what we're doing in a sense is we're taking the internet and using it as the big repeater or the mother ship and each of these individuals repeaters that have the DMR access are basically logging in to talk groups and using the internet to convey the information to the next repeater that is tuned to that talk group. So in essence, if you're on a specific talk group, all of the repeaters that are tuned to that specific talk group can hear what you're saying and can communicate with you.

The BrandMeister network has thousands of different talk groups available. We're gonna have a look some of those talk groups in just a second here in the CPS programming function of our Anytone 878, I'm gonna show you what some of these look like and when you are on a specific talk group you can hear anybody else, that is all over the world, that may be on a different repeater or home hotspot that heats up on that talk group. So instead of just having your analog signal with you local repeater, where you can talk to a few guys locally, you're now using a digital signal and you're now using the internet basically as the mother repeater or the central hub to which all of these digital repeaters are hooked and you can literally use your two meters slash four forty handheld to talk to people around the world and there you have it, digital mobile radio. Now right now, I'm gonna go ahead and switch over to the CPS software, this is the software that we use to programs up our DMR handhelds or our DMR mobiles.

We're gonna look at a few of these digital channels, I'm gonna go through just a little bit of the terminology here for ya. Let me go ahead and start this digital channel here. So we have the frequency pair that we have programmed in like we do with most repeaters. This is actually programmed for a hotspot or a home simplex repeater type device that you can get from us the DV mega hotspot, it's like having you're own home DMR repeater that plugs right into the internet that you can access these talk groups on. Let's go a little bit into these talk groups here though, a little bit more into these talk groups, shall we? Right now we have the USA talk groups selected that is the nationwide talk group selected, it's a fairly busy talk group as I'm sure you can imagine with people getting in from all over the United States. In HF terms I would imagine this type of talk group to be more of a calling frequency and some of these lesser-known talk groups would be more like what would be a simplex frequency so you'd make your initial contact say on the USA and then you might say hey, meet me over on Tech310 or hey meet me over on BYRG, meet me over on the statewide talk group, meet me in my city-wide talk group, and we would take the conversation from this talk group over to the next.

So the USA talk group is programmed in this particular channel slot. We have our frequency pair. We have it set as a digital channel. Notice the band width of twelve and a half kilohertz. And even on this twelve and a half kilohertz ban width, we have two time slots. We have a time slot one and a time slot two. Now in terms of repeaters, most repeaters reserve time slot one for club nets and other things that standardly go on on a local repeater. They usually free up time slot two to use with talk groups, be it United States talk group, be it the world wide talk group, be it the North American talk group, be it your local city or state talk groups, or be it special interest talk groups wish to exist as well. But usually time slot two is set for talk groups, usually time slot one is set for repeater or local club net activity. This can change some repeaters use time slot two for their local stuff and time slot one for the talk groups so it can change via repeater in sisapp and it's important to know which talk group your sisapp wants to be used for what just to stay in good terms, of course, with your local ham radio club and prevent from having your DMR ID number being on that particular repeater or group of repeaters. Then we're gonna go over to what's called color code.

We're all familiar with CTCSS function or at least I hope we're all familiar with CTCSS function when it comes to an analog signal, that is a sub-audible tone or code which must be emitted by your radio in order to access certain repeaters. Well, it's the same here except in digital terms it's called color code. We have color codes zero through fifteen which are commonly used by repeaters across the world here. While many repeaters just simply default to color code one, I'm in the Kansas City area here and the BYRG repeaters mostly use color code four. It would actually be adequate just to go to the repeater book and see what time slot and what color code these repeaters are being used on as the time slot and color code is updated quite often by some of these sisapps to their preference. So what will actually be necessary when you're looking for the credentials of a digital repeater to program into your, into your code plug here like you're seeing here on the screen, in order to get these credentials, you'll actually want to go to the actual website for that digital repeater or digital repeater club for the most updated information when programming your radio. Now, some repeaters are actually multime mode as well where you can use an analog signal or a digital signal. Those are a few and far between most repeaters are either strictly analog or strictly digital in those terms.

Now let's have a look at some of the talk groups that are available. This is just a partial listing of talk groups that you can get for your radio. There are literally thousands of them available and it might take my CPS a little while here to populate all of these. I'm just going to read a few of these off, I'm gonna scroll through, it's a massive, massive list here. We got worldwide, we have Europe, we have North America, we have Asia, Australia, German talk group, English talk group, Spanish, Portuguese, Dutch, Nordic, we have Arabic, each of the states have a statewide talk group, we have tech channels or extra communication channels, we have, mentioned the nationwide here is what I was showing you initially. So we have our states and remember as long as the repeater you are on is tuned to that specific talk group, it will communicate to all other repeaters on that specific talk group, we have aeries talk groups, we have Skywarn talk groups, we have just about any talk group imaginable available to you, on the BrandMeister network which is the network most widely used by the Anytone radios that we sell here in the shop and probably the most growth in popularity is the BrandMeister network.

Alright, so that was just a brief introduction to digital mobile radio or DMR. Please stay tuned to our channel. We hope you've enjoyed today's introduction to DMR, we hope you'll consider it so be sure to hit that like button and subscribe to our YouTube channel, 73.

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