DMR 099

Why DMR?

Overview

The first question is usually, why do I want or need DMR? This turns out to be an easy answer in the commercial world, however it can be a bit of a challenge in the amateur realm. The answers are pretty similar for both. DMR is a standards based RF modulation protocol making it easy for manufacturers to build equipment for. What this means to you is choice. Equipment can vary from $50 - $10,000. The DMR standard puts most of the radios on a very even playing field. Each radio must contain some minimum features and comply to certain specifications in order to meet the DMR standard. In this section I'll explain why DMR is a great mode for both amateur and commercial radio operations.

Some Caveats

Not all DMR systems are equal therefore cause an inconsistent experience. From our Mission Statement, we want people to have a consistent DMR experience. DMR systems are typically the limiting factor. I'll dive more into this in the systems section. Commercial systems are not as flexible as the BrandMeister Network, so please be aware that some of the features listed are not applicable to all "systems."

50,000 Foot View

In short, since DMR uses TDMA, the cost of a single frequency or channel provides two talk paths. This means that a single repeater can have two conversations concurrently without interfering with each other. Why is this a thing, or maybe said, why is this important? Using amateur radio as an example, a single repeater is shared by many. Those using the repeater may have different reasons for using that repeater. Those could range from Emergency Communications, to Special Event Support, to Rag Chew (Just general conversation), to Nets, and for Club Business. Typically repeaters are not linked to other repeaters so their area of influence (or coverage) is a draw for the user base. The better the coverage, the more users. In this example, if one of those groups is using the repeater, others could use the repeater but might cause some confusion. Typically when these types of events occur, other groups find another repeater of communication path to support their effort. An example of this contention would be when there is an EMCOM drill on the same day and time as a community special event. DMR solves this use case quickly by supporting two concurrent conversations. There is a hidden benefit that I'll go into more detail later. related to support several groups at the same time.

I'll give a common example for commercial use. School districts have used radios for a long time to support operations. Each school has been operating either a duplex (repeated) or simplex channel. This worked great when you look at just a single school and its operation. Many schools though are on a campus, where 3 or 4 schools happen to share the same property or are close in physical proximity. If there is a security issue at one, this old way of doing business would force a radio call from someone at one school to the office where they would then call via phone to the other schools to advise of the security issue. Using DMR, each school can use 1 timeslot for just the school and the other for all the schools to communicate with each other.

Add a linked repeater system and this just gets better.

Summary