This site will provide information for the WR3IRS Interstate DMR network.
Check back regularly as this site is constantly updated.


This is a how to, and what to do for operations on DMR.
It is available at delmarvadmr.com.
It is meant to be taken constructively, and presented that way. Not everyone will take it that way. But life is too short to worry about the people that think the world revolves around them.
This was written because a new user wanted to learn more about DMR. They were asked for their opinion on how to improve on this information, and of course, that was asking too much. The person didn't bother to respond. They took it as, it was pointed at me. Well, it wasn't...
But since that person decided to take it that way, then maybe the shoe did fit. No matter, please make sure you understand the last paragraph.



The following information is generic to DMR:

DMR in terms of how you operate on HF -
For instance: on 14.300, the Maritime Mobile Net. You get on, and pass your traffic. You don't get on and have a half hour QSO with your buddy. Think of that net frequency as a statewide, or regional talkgroup. It covers a very large area, and there are a of lot stations listening, but not talking. They may be listening for a call from a friend, and then they will move off to clear the frequency. Moving off on DMR, is going to a TAC channel, or a talkgroup that has a smaller footprint.


Time limits: The Brandmeister network, and most c-Bridges have talkgroup time limits on certain talkgroups. The time limit is approximately 10 minutes. This mostly applies to the Worldwide, North America, Statewide and regional talkgroups. Those talkgroups are considered "calling channels". If your conversation will be longer than 10 minutes on a calling channel, please move to a TAC channel. In most cases, time limits would not apply to local area talkgroups, or TAC channels. It is a gentleman's agreement not to get long winded on those talkgroups, due to the number of repeaters that carry them. Not adhering to the time limit may cause repeater operators to place the talkgroup on PTT, or remove it completely. Please set a good example to others, and pass along the information about the time limits to newer stations that may not realize some talkgroups are used as calling channels.


Most talkgroups are either geographically based, or niche based. When using a Statewide talkgroup, at least one station in the QSO should be within the state. If a TAC channel is geographically based, again, one of the stations should be in that area covered by that talkgroup. For instance: Two stations in Florida using PA TAC, would not be correct usage of the PA TAC talkgroup. They could use the FL TAC talkgroup instead. Most TAC channels were created to be an overflow to free up the wide area talkgroups. Specifically, TAC 310-312 are not to be used as a calling channels. They are the common overflow talkgroups. If you decide to hang your hat on a TAC channel, please don't use 310-312. Some repeaters carry TAC 310 as their only TAC channel, so if it is busy, stations may not have another talkgroup they can go to, so they do not tie up a larger area talkgroup.

Please think about when stations are having a conversation on their hotspots, not utilizing a repeater, but causing 50+ repeaters to transmit. The same also applies to stations on repeaters. Many repeaters coming up when only a few need to be used can prevent other stations from using a talkgroup. Then I have heard, well, no one was using the talkgroup. While that may be true, but you do not know if the timeslot was in use on another repeater, and your conversation "stole" the timeslot on a repeater. Some states have gone so far as to disconnect their Statewide TG from Brandmeister because of the hotspot users not going by the rules. If all the stations in a QSO are within the coverage of one repeater, please use Local 9, so you don't unnecessarily bring up other repeaters.

If you are using a niche based talkgroup, the talkgroup was created for a particular interest. For instance, if you are using the JOTA (Jamboree on the Air) talkgroup, please keep the conversations relevant to the Boy Scouts using ham radio.

91 and 3100 talkgroups are the exception to the rule. They are a kind of free for all. I would not tie them up for 15 minutes, but many people do.

When testing, if possible, use the Parrot talkgroup. The Parrot is an audio DVR. It will playback the audio that it hears. 9998 for a c-Bridge connected repeater. 9998 will need to be set as a group call. 9990 for a Brandmeister connected repeater, or a hotspot. 9990 will need to be set as a private call. Your DMR radio does not broadcast your FCC callsign, so you must always ID.

Don't keyup and start speaking, unkey, and then rekey. This action apparently came from HF. Besides being annoying, it can cause doubling. Due to delays the in the linking of DMR, doubling is always a problem, so please don't add to it.

Please do not call CQ. Using monitoring, or listening is sufficient. Many people monitor, but they may not be able to transmit. They could be at work, or have other people in the vehicle. Just because someone did not come back to you, doesn't mean no one is listening. It just may not be convenient for them to get into a conversation at that time. Calling CQ for 5 minutes straight, will cause many stations to turn their volume down, then there will be little chance for you contact them when they may be in a position to transmit.

Please do not transmit and receive using different talkgroups when having a conversation, that ties up two talkgroups, and most stations will only hear one side of the conversation. That usually occurs only when using a digital monitor mode. Please make sure all the stations in a QSO are on the same talkgroup.

Enable the "Call Idle tone" on your radio. That will indicate when a station has stopped transmitting. That will eliminate a need for the monotonous "over" at the end of each transmission. Also, leave a few second pause after a station unkeys before you keyup. From when you transmit, there could be up to a 4 second delay before the other station hears you. It is very easy to block a station trying to get in. Pause a few seconds between transmissions. It will make it much easier for other stations to join, or break in.

Do not repeatedly key up a PTT talkgroup on a repeater to hear traffic. Repeaters are not a personal scanner. PTT talkgroups are PTT, so they do not continuously tie up a timeslot. You are welcome to kerchunk a talkgroup to see if there is traffic before making a call, and that is a good practice. Do not transmit more than once, unless you are intending to make a call to another station, or to say you are monitoring.

When making your initial call, announce the talkgroup name you are on. Some stations may not know what talkgroup you are on, and they probably aren't going to try to guess where you are to have a QSO. Some radios do not have a display, or maybe visually impaired. That would be a problem for them to know what talkgroup is being used, so they could join the conversation. So let those folks know what talkgroup you are on.



Definitions of some DMR jargon:

Brandmeister (BM) - An amateur radio designed system that can connect/manage many brands of repeaters, and hotspots.

c-Bridge - A Motorola Product. It is licensed server that can connect/manage up to 50 repeaters. It was designed to primarily connect Motorola repeaters.

FT (or static) - The talkgroup is nailed up. It exists all the time on a timeslot, unless a hold off timer prevents it.

PTT (or dynamic) - The talkgroup is only activated by usage on the local repeater. It times out after a certain time of no activity from the local repeater. That means if the repeater heard no transmissions locally, the TG will time out, and be removed.

TS - Timeslot

TG - Talkgroup



The following information is specific to the repeaters connected to the Interstate c-Bridges:

The Interstate Network believes DMR to be the most versatile, and the most bandwidth efficient digital mode. That being said, Interstate will not intentionally pass traffic from other digital modes.

Most of the talkgroups on the Interstate c-Bridges follow a general template. This is to say, the talkgroups that appear on each repeater are logically placed on certain timeslots in an attempt to balance traffic across the timeslots on each repeater, but also keeping some uniformity.

When two talkgroups are active at the same time, on the same timeslot, and it is a common scenario, the c-Bridge will hold-off other talkgroups that could barge in, causing a disruption in the transmission of the wanted talkgroup. A common scenario would be, the in-State TAC channel holding off your local Statewide talkgroup on TS1.

An uncommon scenario would be, while using a distant Statewide talkgroup, your Local 2 talkgroup goes active. In that case, the Local talkgroup would "steal" the timeslot. When the timeslot is stolen, it interrupts your conversation. That can be prevented by using a "MCT" command. The MCT is a Master Control Talkgroup. That will clear the timeslot for 15 minutes, so the timeslot you are using does not get stolen. The MCT talkgroups are not used for voice, they are used to control the traffic on a timeslot by kerchunking the talkgroup for a few seconds. The MCT talkgroup command IDs are: 4001, 4002, 5001, and 5002.

The Interstate template looks like this:


Hold-off timers are generally 6 minutes. PTT timers are generally 15 minutes, but some are 5 or less.

All repeaters have a Local 2 talkgroup. Depending on where the repeater is, determines what other repeaters are linked to that specific Local 2.

Local 9 is a standalone TG. It only keys up the repeater you are on. Local 9 exists on both timeslots, but they do not connect with each other. You could have a conversation on Local 9-1, and someone else could be using Local 9-2, and the conversation on the other timeslot will not interfere with yours. Local 9 will hold off most of the other traffic on a timeslot.

The regional group(s) that covers the area that the repeater is in, are FT on TS1. The other regional TGs are also on TS1, but are PTT. There are repeaters in many states that come up when a regional talkgroup is used. The NE Regional talkgroup keys up about 500 repeaters when it is being used.

The In-State TAC TG(s) are usually on TS1 as PTT. The In-State Statewide TG(s) are usually FT TS1 with hold-off timers against them. The PA Statewide talkgroup keys up more than 50 repeaters.

The Local TGs in the specific area are usually FT on TS2. They can hold off other Local TGs.

The widely used TAC channels are PTT on TS2. They can hold off local TGs.

Distant Statewides are on TS2. They usually have no hold off timer protection.

Of course, there are exceptions, but this is the way that most of the Interstate connected repeaters are configured.


In closing, when you go to someone else's house to play, you need to play by their rules. If you don't, you're not invited back. There are reasons why these rules/guidelines are in place. Someone did not just pull them out of a hat. These were put together over years trying to improve the way amateurs could more efficiently use DMR. If you don't agree with the rules, buy your own house to play in. Keep in mind that you are a guest on whatever network/repeater you are connected to, unless it's yours.

It may be a lot to ask, but please do your best to play nicely in the DMR sandbox with others.


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