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#85 - Dual DMR Experiment

I have been using the Shark RF OpenSpot2 hotspot to access the BrandMeister DMR network for the past few weeks, so I decided to try an experiment.

A few days ago as I was changing talkgroups in my DMR radio I had a curious thought. My radio has two VFO lines that can be set to either VHF or UHF to monitor two frequencies at once. I wondered if that would work for the DMR talkgroups as well.

After speaking to a few other DMR users we came to the conclusion that no one that we know had ever tried it to see if it would work or not, so, why not try it and see.

I knew that if I merely set each VFO to a separate talkgroup using the OpenSpot2, it would only monitor one at a time, and when I keyed up the talkgroup on the other VFO, it would lose the connection to the first talkgroup since the OpenSpot2 would only be listening to one talkgroup at a time. The solution seemed simple, have two separate hotspots.

I ordered a second OpenSpot2 and it just arrived today. I have set up the second OpenSpot2 on a different frequency than the one I have been using, just far enough apart on the UHF band that they will not interfere with each other. I have connected both hotspots to my wifi router and have locked in their IP addresses so that if they are disconnected, they will reconnect using the same IP address again. I have them now set to two different DMR talkgroups.

Over the next few days I will be trying out different experiments with using the radio to monitor two talkgroups at the same time. So far everything looks like it will work as I intended. With my current settings the radio is monitoring both talkgroups. When one talkgroup becomes active the radio should lovk on that talkgroup until the end of the transmission and then monitor both once again, in the same way that the Dual Monitor function operates on the analog side of the radio.

One of the experiments that I want to try is setting one talkgroup as the Priority channel with the other one being secondary. I want to have someone transmit on the secondary talkgroup and then have someone start transmitting on the priority talkgroup at the same time. If it works correctly, the radio should switch over from the secondary to the priority talkgroup's transmission, which is exactly what it does on analog. This is one of the great unknowns though, so we shall have to wait and see if it works or not.

I am also setting up a Portable DMR Comms bag which will hold both of the OpenSpot2 units, along with my AT&T Access Point router and five 12,000mAh battery packs that is small enough that I can carry it with me everywhere I go so that I always have DMR access anywhere on the island.

One of the things that I like about the OpenSpot2 is the ability to cross link between the various digital networks so that I can use my Ailunce HD-1 radio to talk on System Fusion, D-Star, P-25, BrandMeister DMR, DMR-MARC, and several other networks without having to buy individual radios to access those networks.

Once I finish with this experiment I will start experimenting with cross-linking and try out some of the other networks that I have never been able to access before.

Until Next Time,

Aloha & 73 From Hawaii


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