Understanding DMR repeaters and duty cycle

[Project25_MASTR]

I'm still confused a little on the public vs private use of repeaters. As buddrousa stated if it is on a ham band all should be able to be use it, and I agree 100% if I want to use one extensively it's only fair that I help pay for the maintenance of it.

There are things called closed repeaters. They are permission required repeaters essentially (not open to the general public). Often times, they are part of groups or clubs and are paid for services (where the subscription goes to further maintenance and expansion). Two great examples of closed systems are the Cactus and Armadillo Interties (which have an inter-group agreement so Cactus members can use Dillo sites and Dillo members can use Cactus sites). It's a closed wide area system...but has quite good coverage across some key areas. Members pay to maintain the system cover operating costs (tower space isn't free...especially 800+ feet off the ground). The FCC does allow for closed systems.

It is also important to note, just because a DMR repeater is linked...doesn't mean it has internet access.

 

[bill4long]

It was burning up their repeaters

 

[Hit_Factor]

... if I want to use one extensively it's only fair that I help pay for the maintenance of it. I also agree with NoiseLimited - most of the articles I've read say something to the effect of "Hey attach to a repeater and listen round the world for hours, whatever interests you." ...

Around here club membership (Dues) contributes to the care and feeding of repeaters.

 

[bill4long]

I'm new to the amateur radio world and trying to understand the digital options. In looking at DMR I ran across some info that seems to be conflicting. I thought one of the pros of DMR was to be able to find a talk group and listen at length if the discussion was interesting. There was some direction given from a club that said don't use our repeaters to go to these never ending talk groups. It was burning up their repeaters because the transmitters were running full power the whole duration. I would not want to be the cause of failure for someone else's equipment so I'm confused. Is the proper etiquette to contact the owner and ask permission to use his repeater? It sounds like a hot spot is a better option if I choose to go the DMR route, or it it a problem with D-Star and Fusion repeaters as well?

Mark

Spend $100 and get your own hotspot for DMR. Then you won't bother any local repeaters. That's what most people do these days. You can also make your own hotspots for Echolink, IRLP, and Allstar too, although, I think it's a waste of time these days. DMR is there the action is. DStar reflectors and Fusion hubs can be accessed with those DMR hotspots too, to a large degree.

 

[bill4long]

I don't understand comments like that. The repeater is likely to be largely unused otherwise.

His comment literally made me LOL. If they are using a commercial repeater, such as Motorola or Hytera, nobody is going to "burn it up". However, he may irritate some people. What I find hilarious is that some of these guys spend the $ on a repeater system, then it goes largely unused except for maybe a weekly net where three people check in. Whatever. Easy to end-run around the problem, and that is using hotspots.

 

[bill4long]

Not all DMR repeaters, even from a single manufacturer, are 100% duty cycle rated. Ham clubs tend to buy the cheapest stuff, then gripe about repair and replacement costs later. Some of the lower end units are no more than two mobile RF decks mounted in a rackable box. Those are not designed to run for hours at a time. So yes, having those linked to a busy talk group for hours ata time is reducing the service life of the repeater. Ya get what you pay for.

Nobody in their right mind would use one of those short duty repeaters for ham radio (such as the GR-300 which uses two GM-300 mobiles) without adequet cooling on the transmitter. And it's very easy to acheive. But maybe this particular club is doing just that. Who knows. But if it's a DMR repeater, I seriously doubt it is some cheapie repeater. Anyway, the OP has simple and cheap options.

 

[Project25_MASTR]

His comment literally made me LOL. If they are using a commercial repeater, such as Motorola or Hytera, nobody is going to "burn it up". However, he may irritate some people. What I find hilarious is that some of these guys spend the $ on a repeater system, then it goes largely unused except for maybe a weekly net where three people check in. Whatever. Easy to end-run around the problem, and that is using hotspots.

Actually (bear in mind, I am a former Motorola tech) the first two generations of Motorola DMR repeaters (XPR8300 and XPR8400) were known for issues related to PA failure in high use environments (remember the max transmit duty cycle of a DMR subscriber is 45% where a repeater can have a max up to 100% since it transmits over the sync periods and both timeslots regardless of inactivity on one timeslot). While this could be better fought by using an external PA and forcing the fans to constantly run over time they units will fail (there's even a Motorola FSB out there stating the repeaters shouldn't be utilized for control channel function).

 

[bill4long]

If it’s an open repeater then it’s an open repeater

Repeater owners can set the rules for using their repeater. And they can ban people they don't like for any reason whatsoever. So it's not as simple as you say.

 

[OhSixTJ]

Repeater owners can set the rules for using their repeater. And they can ban people they don't like for any reason whatsoever. So it's not as simple as you say.

I meant that if they don’t take steps to restrict use then it can be used by anyone. Rules and bans or whatever are different.


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[N4GIX]

Most DMR ham repeater owners/trustees carry only a very limited sub-set of talk groups. My local UHF carries only 8 TGs on Slot 1 and 6 TGs on Slot 2. All of the TGs on Slot 1 are "PTT Activated" and carry a 15 minute timeout unless the timer is reset by local activity. On Slot 2, Local (true), Indiana Statewide and Midwest Regional are the only TGs "full time", with the other two TGs UA English 2 and TAC311 are PTTA. The VHF repeater is similarly configured. The TGs available are only those which the owner/trustee has made available.

PTTA was done precisely to stop the clueless who could never grasp that when they motor mouth on Worldwide English they are potentially keying up several thousand repeaters all over the bloody world! Talk about wasted resources.

Consequently, in both my shack and my car I have my radios programmed for the local UHF and VHF DMR repeaters to access all the TGs available, but still use my hotspots to access anything other than the Local or IN Statewide Groups.

The only drawback to hotspots is that they are unable to access the Local TG since it isn't connected to the Internet at all. The major advantage is that I'm able to control precisely which TGs I want into my hotspot. So it's a win-win for everyone.

BTW, in the spirit of amateur radio, both repeaters are freely "open" for any licensed amateur to use, as are all DMR repeaters in the State of Indiana.