Maximum Coverage from DMR systems

So recently heard on the air was a discussion about working DMR systems from an airplane; During that talk, there was a claim the repeater was able to be worked with a full bi-directional conversation from a couple hundred miles away.

I was really surprised. I’m fairly sure reception is possible over tremendous distances, but you would be unable to hold the proper time-slot with a TDMA network like Tera and DMR.

Here’s a discussion I found online: http://forum.motorola-radio-support.co.uk/index.php?topic=1035.0  And here’s an FAQ from Tait: http://blog.taitradio.com/2013/09/26/dmr-digital-mobile-radio-frequently-asked-questions/  and: http://owenduffy.net/blog/?p=9133  and: http://www.va3xpr.net/search-range-limit-dmr/

I thought I’d toss this out there to see what others may know or think about this?

I wondered if maybe its possible but you risk stomping on the other time-slot had there been two time-slots in use towards the repeater?

I’m quite certain that with DMO mode aka a Simplex radio connection where there is no need for syncing or precise timing, there would be no problem. This impacts only repeater operation where both time-slots are in use.

For anyone wanting to claim D-Star and Fusion are better than DMR, this might be one example of where they may be. But I’m happy with DMR and it’s ability to carry two conversations from one pair and it’s lower power consumption. The world is full of trade offs.

One thought on “Maximum Coverage from DMR systems

  1. Personally, I don’t consider a 90-mile limit on repeater-based DMR coverage to be a serious disadvantage of the mode. It’s an interesting constraint, to be sure.

    If VHF DMR repeaters ever take off in the out-state areas, it might become an issue — especially with tropo. Maybe talkaround would be an alternative for those infrequent cases. And it’s much less likely that both slots would be in use simultaneously on a rural repeater.

    One thing that comes to mind is DMR satcom. It seems that this would be impractical for high-orbit applications. Realistically, DMR EME is probably out of the question, too. As you said, there are trade-offs in any mode.

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