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Hearing more DMR on 446.

Posted: Thu Nov 11, 2021 8:57 pm
by dc260
Recently I have been hearing a lot more DMR activity from businesses and schools on 446.

Now I want to make a distinction as there is confusion over digital modes on 446, DMR is DIFFERENT to dPMR.

DMR is a digital protocol that relies on TDMA (Time divison multiple access) which allows two groups to communicate simutaniously on the same frequency (The frequency is split by time, one timeslot after another).

dPMR is also a digital protocol but relies on FDMA, frequency division multiple access, the channel is split into two smaller channels allowing two groups to communicate.

Now when I mention DMR on 446 , I am in fact talking about the first type, not the second dPMR.

The DMR channels are the same as the 16 analog channels in frequency, whilst dPMR has 32 channels (Because each channel is split by frequency into two channels side by side).

License-free DMR sounds like a machine gun or helicopter sound in an analog radio, in order to receive if you must use an SDR running DSD+ (Digital speech decoder) or own a scanner/radio capable of decoding DMR.

An example of a license-free PMR446 DMR radio would be the Retevis RT40 or Hytera PD365LF.
Prices have gone down signifcantlly on these types of radios, so we may see an increase in traffic as a result.


Have you heard any DMR traffic on 446 in your area? If so post about it.

Re: Hearing more DMR on 446.

Posted: Fri Nov 12, 2021 3:22 pm
by Username
I do have a DMR radio but I never seem to remember to take it out with me.
I'll try and remember for this Sunday night!

Re: Hearing more DMR on 446.

Posted: Thu Nov 18, 2021 7:10 pm
by TM205
So DMR446 is on the exact same frequencies as PMR446?
And is it also licence exempt or not? As most DMR radios are higher power.
So is DMR legal on 446 under licence exemption or do you need a private licence.
If it is licence free I can see PMR446 being overrun with digital?
Can anyone clarify the legality and licence needed please? :( :(

Re: Hearing more DMR on 446.

Posted: Thu Nov 18, 2021 11:25 pm
by Bozzy
The below link may help, it is confusing though as you suggest.

https://kenwoodcommunications.co.uk/fil ... _JT_KB.pdf

Goto page 5.

There is Analogue, DMR and DPMR frequency allocations...

Regards
Bozzy

Re: Hearing more DMR on 446.

Posted: Fri Nov 19, 2021 6:12 am
by dc260
TM205 wrote: Thu Nov 18, 2021 7:10 pm So DMR446 is on the exact same frequencies as PMR446?
And is it also licence exempt or not? As most DMR radios are higher power.
So is DMR legal on 446 under licence exemption or do you need a private licence.
If it is licence free I can see PMR446 being overrun with digital?
Can anyone clarify the legality and licence needed please? :( :(
That link that Bozzy posted helps.

Also in short:
Yes it is on the same frequencies as PMR446.
It is license-exempt, think of DMR as another mode to FM which is permitted under the PMR446 standard.
It's not the case that they are reprogramming high-power radio's to 446, but they are purchasing radio's that are designed and within the PMR446 specification.

Some examples:
https://hytera-europe.com/products/pd365lf
https://hytera-europe.com/products/pd355lf
https://www.retevis.com/rt40-pmr-digital-business-radio

All of these are low-power (0.5 watts) integrated antenna PMR446 radios that operate on DMR that do not require a license.

What makes it even more confusing is there is also another digital standard called dPMR, but it's completely UNRELATED to DMR.

I might make a page on the main site to help make digital modes on 446 more clear! :D

Re: Hearing more DMR on 446.

Posted: Sat Dec 11, 2021 10:54 pm
by TM205
Thanks for the info, most appreciated.
I will have to program my radio up.
Cheers Mark :thumbsup:

Re: Hearing more DMR on 446.

Posted: Sun Dec 19, 2021 11:08 pm
by Bear
It would be nice to see more activity on dmr, its rare i hear it and mabie because some ppl dont know how to program the radios for it. it is quite easy once you know how. when i upload more codeplugs i will add dmr for 446 also, that may help some ppl.

Re: Hearing more DMR on 446.

Posted: Tue Feb 15, 2022 8:57 am
by TM205
Well Ive not heard any DMR in the Stoke-on-Trent area. Apart from all the commercial licenced stuff up on 450MHz band.
446 Analogue FM is very busy around here during the day, a lot of business use around the city. 3 different Motorcycle trainers as well as warehouses and some medical use. and ofcourse the usual kiddies beeping radios when home from school, but sadly no sign of any DMR.
I was thinking of the possibility of a hotspot maybe would this be legal at 10 mW it meets the licence free stuff for power level.
I think it could be interesting if networked DMR use is alowed?
Hmmm