DMR - if you cause QRM how can the Primary User ask you to stop/QSY?

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RogerD
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DMR - if you cause QRM how can the Primary User ask you to stop/QSY?

Post by RogerD » 01 Feb 2016, 00:29

Say you pick an out of the way 70cm channel and start chatting on DMR, but it's a Primary User's channel. If you were on FM they could ask you to move. How are they supposed to do that if you're on DMR and you're blissfully unaware of what's happening on the actual radio channel? All you hear the the decoded audio from the digital stream, anything else on the frequency is hidden from you.

??

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Re: DMR - if you cause QRM how can the Primary User ask you to stop/QSY?

Post by Admiral » 01 Feb 2016, 08:19

This could have gone in the new digital section.

I guess you can't use DMR within 65 miles of Charring Cross on 431-432 either?

I'm sure the MOD could switch to DMR to ask you to bugger off if they wanted to.
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Re: DMR - if you cause QRM how can the Primary User ask you to stop/QSY?

Post by kr0ne » 01 Feb 2016, 09:48

Do primary users ever make such requests (or are they even allowed to?) over the air?

Genuine question. Never heard of it happening and the terms of our license would certainly prohibit us from responding...

As I understand it, we are generally required to avoid interfering with primary users as far as possible by listening before beginning to use a frequency and any interference complaints would be handled by Ofcom in the normal way.

The amateur license is quite clear about our responsibility in terms of being able to receive messages in the same "frequency and class" as transmissions are made, if you take the trouble to read it.

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Re: DMR - if you cause QRM how can the Primary User ask you to stop/QSY?

Post by paulears » 01 Feb 2016, 10:15

My understanding (based on old Cold War procedures and the Olympics) is that the Primary user, in this case the MOD doesn't make an attempt to use the 430-440MHz band in day to day activity. Look at the time it took to clear channels then - lots of publicity with the clubs, organisations and other interested parties. As Amateurs are the secondary users, access is on a grace an favour basis, but from the MOD's point of view, they could do what they wish, but in practice, why use a band where within hours, maybe minutes, your usage is circulated and everyone listening in, or interrupting it?

They have access to much more sensible and practical bands. I dare say that they could use 70, but in practice, I doubt it.

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