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DMR Reflectors

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DMR Reflectors

As described in the repeaters section, some c-Bridges severely limit the Talk Groups a repeater can access. What happens when you’re travelling to Melbourne and want to talk to your buddies back in Perth? Or worse, talk to a buddy in England? Talk Group options become limited to wide-area ones which tie-up a lot of repeaters for a lengthy QSO. Reflectors are a way to solve this problem.

Similar to D-STAR or IRLP reflectors, nodes are connected in a round-table style configuration. When one station transmits, their signal is transmitted by all other connected nodes. So far, these sound like Talk Groups. The difference is reflectors are available worldwide and repeater users have to specifically link and unlink a reflector. This means only repeaters and hotspots connected to that reflector are tied up during transmissions and not thousands of repeaters on world-wide Talk Groups.

Reflectors are a 4-digit ID that begins with a 4, 4xxx.

 

Not every c-Bridge has granted reflector connectivity. DMR-MARC and Brandmeister have this ability. Some reflectors are cross-patched to Talk Groups on Brandmeister so either the reflector or Talk Group ID can be used. Reflectors are seldom used on Brandmeister because of the availability of all Talk Groups to all repeaters and hotspots on the network. However, reflectors still serve the intended purpose if a station isn’t in range of a Brandmeister repeater.

Connecting to reflectors from Australia

Reflectors can be accessed on talk group 9 on slot 2 (DMR+ Network)

 

Here’s the trick. To access reflectors, you’ll need to program your radio a little differently.  First, check the status of your local repeater on the website or use talk group 5000. Now connect to the reflector you want by programming its number as your TX talk group. For example, talk group 4400 is UK Calling. When you’ve established the connection, use talk group 9 for both TX and RX for the duration of the QSO. Finally when you’re done disconnect the reflector from the repeater by TX on talk group 4000 or do nothing and the talk group will time out and revert after 15 minutes.

Programming your radio

The easiest way to access reflectors is by programming sequential memories with the appropriate talk groups.

 

  1. Choose your local repeater and program the following channels on time slot 2.
  2. Channel 1: TX – talk group 5000 RX – talk group 9 (Check repeater)
  3. Channel 2: TX – talk group 4400 RX – talk group 9 (Establish Reflector connection)
  4. Channel 3: TX – talk group 9 RX – talk group 9 (QSO)
  5. Channel 4: TX – talk group 4000 RX – talk group 9 (Disconnect)

Reflectors must be manually linked and unlinked. Time slot 2 is always used for reflectors and associated commands.

How to use Reflectors

You’ll need your DMR Radio handy as well as your openSPOT 2 that is connected to the internet and your web browser open and ready to go.

 

Connect to the DMR server on your web browser and make sure you’re listed.

 

If you’re not sure how to do this, go to http://openspot2.local/#connectors and scroll down to the DMR/Homebrew/MMDVM section where you’ll see the server IP address. Copy the IP address into a new tab on your web browser and you should see the server dashboard. Scroll down and find your callsign. The settings of your openSPOT 2 should be visible here.

 

If you’re in Australia, chances are you’ve connected to the IPSC2-AUS-2 Server.

openspot2 login

For this exercise, we’ll connect to Scotland. Why not? This is where reflectors come into their own. Have a look at the  Phoenix UK and Europe DMR Network reflectors. Scroll down to the Current Phoenix Reflectors and you’ll see Scotland is Reflector 4450.

OpenSPOT2 Reflector settings

Hopefully, you’ll still have http://openspot2.local/#connectors open. Scroll down to the MMDVM options for DMRplus section. If you can’t see it, make sure you have the Advanced Mode checkbox ticked in the lower right-hand corner of the openSPOT 2 web page.

 

Next, Make sure Use DMRplus options is checked. Then open the dropdown in the Start reflector option. Scroll down until you find reflector 4450 Scotland. Select it. The dialogue box immediately underneath it – Start reflector ID will now show 4450.

 

Don’t forget to scroll up and click the SAVE button next to the DMR/Homebrew/MMDVM section title in the panel you’ve been working in.

 

This is all you have to do using the web interface on the openSPOT 2.

Now head back to your local server’s dashboard and look at the entry for your station. You should see the Scottish 4450 reflector now listed on the right-hand side of your entry.

If you haven’t set up the link between your DMR radio and the openSPOT 2 properly yet, make sure you have a memory channel set up for talk group 9 on slot 1. I have a zone set up for my openSPOT 2 with a collection of talk groups programmed. You’ll use this channel, TG9, to transmit on, and receive the reflector.

 

Select TG9 and transmit. You’ll see your entry on the local server’s dashboard turn green if you’ve successfully set everything up correctly. To make sure you’re making it to Scotland thanks to the magic of DMR, head over to the Scottish DMR dashboard. Transmit again, and you should see your callsign appear in time slot 2.

 

Job Done! Happy DXing. Well… you know what I mean.

Reflectors Server

Each radio used on the DMR network is programmed with a unique user ID number and
y
ou MUST register your radio for it to work correctly.

 

IDs are personal. You can have one ID on many radios. It’s like a digital callsign. Don’t share it.
ID numbers are managed centrally and may be obtained here.

 

You can see what the Australian Network is doing in REAL TIME.

VK RF DMR Server

IPSC2-VKDMR Server – (VK Repeaters)

As of June 2019, The VKDMR server is one of two Australian servers. This server is for VK RF Repeaters only. The second server is yet to be publically announced. The VKDMR server is part of the worldwide Amateur Radio DMR digital voice network, which connects Amateur Radio repeaters and hotspots together. Users with a valid Amateur Radio license may connect their Repeaters and Dongles freely and use it within the local and international Amateur Radio regulations.

 

The top panel of the site shows connected stations. A real-time summary of the network is below. Here you can see the two timeslots in action. You’ll note the hard-wired talkgroups in the TS1 (Timeslot 1) and TS2 (Timeslot 2) columns.

 

If this site is active, the TS1-INFO or TS2-INFO columns will display the digital ID and Callsign of the user. Orange signifies an output and green an input to the system. The TS1 and TS2 show the fixed (non-user activated) talkgroups on their respective slots.

IPSC2-VKHOTSPOTS

IPSC2-VKHOTSPOT Server – (VK Hotspots)

This is the second Australian server connecting DMR to the network. This role of this server is primarily for hotspots. A hotspot is a small modem that acts as a personal access point for an operator. This allows an amateur to access DMR even if they can’t access a local repeater. A user uses a digital handheld to transmit to the hotspot which is connected to this server via their home internet connection or mobile phone.

 

Most hotspots are connected 24/7. There are no restrictions on who can connect to the server except for one – all users MUST be a licenced radio amateur. Radio IDs are ONLY issued to licenced amateurs after authentication. This is why the ID allocation system is not real time.

When you’re programming your new digital radio or hotspot, make sure you have these servers on a screen near you so you can see if you’re connecting to the right timeslot and on the right talk group.

Need a hand?

DMR is an exciting new mode for the what seems to be the ever-evolving hobby of amateur radio.

 

As it’s always changing with new radios, new repeaters, and different ways of doing things, it would pay to join The VK DMR Network group on Facebook. Here you can keep up with all the goings-on in DMR, and of course, if you get stuck or confused, chances are you aren’t Robinson Caruso and someone in the group will be able to help out.

 

It is a closed group so be sure to ask for membership which shouldn’t take too long.

VKDMR facebook
VK3FS