Transmission1

gmham wrote:Yet to hear any dmr 446mhz activity yet.anyone else aware off much activity thru the UK? Or is everyone keeping 100%" legal and using dpmr?

DMR is legal too on PMR446. Admittedly not the higher power (above 0.5W) radios used in the amateur and commercial bands but then neither are higher power dPMR radios.

I have heard some builders and crane operators using DMR on the digital PMR446 channels. Apart from that, I haven't heard anything else on them.

Okay cheers.

Bringing back an old thread !
Anyone here running DMR on 446mhz ? Anyone confirm the latest U.K. *DMR freqs on 446mhz ?

* DMR as opposed to DPMR

gmham wrote: ↑17 Sep 2021, 20:06 Bringing back an old thread !
Anyone here running DMR on 446mhz ? Anyone confirm the latest U.K. *DMR freqs on 446mhz ?

* DMR as opposed to DPMR

They are exactly the same as the 16 regular analog PMR446 frequencies

Okay thanks thought that was the case but found this link tonight and look at what freqs they are giving for 446mhz DMR channels. Different from the analog freqs ?

Ex. 446.10625 for ch1 DMR ?

Poss an old link as I am sure there are 16 analogue channels now as well yep ? They are only showing 8 .

https://www.radiotronics.co.uk/blog/201 ... equencies/

Hey there Im always using DMR on 446mhz.

The channel setup I use for DMR is:
446.00625   CC1   TG1   S1
446.01875   CC1   TG1   S1
446.03125   CC1   TG1   S1
446.04375   CC1   TG1   S1
446.05625   CC1   TG1   S1
446.06875   CC1   TG1   S1
446.08125   CC1   TG1   S1
446.09375   CC1   TG1   S1
446.10625   CC1   TG1   S1
446.11875   CC1   TG1   S1
446.13125   CC1   TG1   S1
446.14375   CC1   TG1   S1
446.15625   CC1   TG1   S1
446.16875   CC1   TG1   S1
446.18125   CC1   TG1   S1
446.19375   CC1   TG1   S1

AshtonMobileScanner wrote: ↑18 Sep 2021, 12:15 Hey there Im always using DMR on 446mhz.

The channel setup I use for DMR is:
446.00625   CC1   TG1   S1
446.01875   CC1   TG1   S1
446.03125   CC1   TG1   S1
446.04375   CC1   TG1   S1
446.05625   CC1   TG1   S1
446.06875   CC1   TG1   S1
446.08125   CC1   TG1   S1
446.09375   CC1   TG1   S1
446.10625   CC1   TG1   S1
446.11875   CC1   TG1   S1
446.13125   CC1   TG1   S1
446.14375   CC1   TG1   S1
446.15625   CC1   TG1   S1
446.16875   CC1   TG1   S1
446.18125   CC1   TG1   S1
446.19375   CC1   TG1   S1

Okay thanks that’s great. I take it you can use any TG number you want as a setting bearing in mind the radio you want to communicate with has to be on the same cc1 / S1 ? I know some TG numbers relate to amateur radio DMR groups , take it that’s all separate and you can still use the same number as them ie. nothing is exclusive use ?

I'm not sure. DMR for 446 has a specification, I think it's called Tier 1 or something. This might specify talkgroups/colour codes etc but as I've not read it I don't know. Personally, I don't see a problem with using whatever TG/CC you like, but then if you want to hear anyone else it would make sense to stick to the same one. I think TG9 is the standard for simplex ham, but I don't know why. TG1 seems to make more sense (to me), but I'm late to the DMR game so I don't know why.

DMR Tier 1 is the DMR version of simplex..

Mike

Ok cheers Mike.

Since encryption was mentioned :-

You'll find, because the UK usage of DMR on 446 is actually governed by a specific subset of EU spec, that since use of high encryption without Nov license extensions (commercial, ham and hobby/leisure radio use on ANY allocation) isn't permitted under standard licenses and you'll need a pretty damn solid justification to even have a sniff of a chance at getting cleared for high encryption use.

So, at best, you'll be using legally the 'common' mode (as often called in CPS's and in radio channel menu settings on keypad programmable sets) and that's a bit grey area (but since it's really more a voice scrambler within the codec - akin to analogue voice scrambling on NBFM, pretty much useless). The only upside to commom mode encryption is that within DMR DV operations, it's doubly obfuscated by virtue of the fact that DMR transmissions are completely human ear unintelligible so casual analogue users won't know if it's open or encrypted.

Common mode, unfortunately, has zero security vs a DMR set that can be put into monitor mode as that tells use the CC/TS and ID used on the transmission and such a set, usually keypad programmable (such as an AT-D878) can be selectively moved between open and common mode encryption quickly enough to cycle between the various permutations (bugger all few).

The high level encryption (AES on every HE supporting radio I've encountered) is definitely beyond casual hacking attempts to crack/snoop especially where traffic is short and infrequent as the less sent, the less packets can be captured and most fast bruteforce cracking relies using captured packet stream to isolate the unique packets to build up a mask which (given enough unique vectors) can then be used to demux live or recorded transmission. Note, that's the way WEP was cracked, the difference with more advanced digital encryption is that you'll need vastly more IV's obtained to create a mask (a huge amount vs say 10000 needed for WEP) so essentially forget live snooping unless you're talking a very professional bit of security grade hacking kit such as GCHQ (or whatever it's called these days) would have access to.

But between the IV overhead, and if traffic is short and infrequent, at best BF attempts vs AES are only good for evidence gathering, pretty much DOA for live monitoring without some pretty pricey kit you'd really never justify possessing on any level as a civilian radio user.

As for the TS/TG on 446 query - I'll review my full text of my Tier 2 license (as my non ham use sets were preprogrammed and secured, so snooping via CPS isn't an option easily) and post my evaluation of things in another reply.

BTW - the 1/1/1 standard often cited on websites for ham simplex is an American common standard. They also use an alternative combo for stuff like on site at rallies/events, but I don't recall it offhand as I'm a UK ham so uninterested in following what's 'common' in the USA ham DV wise.

Chris_M1BIK wrote: ↑06 Dec 2021, 06:56 Since encryption was mentioned :-

We wish we had not mentioned it now

Mike

I tried some DMR simplex on 446 recently with someone across town.
We simply used CC1, TG1 and Slot 1 across all 16 channels. Works perfect and should be easy enough for anyone to program on various models. If you're wanting to make random contacts like on analogue 446 then that's probably the best way to do it!

If the aim is to be able to talk to as many people as possible, all the encryption, slots and groups is a bit pointless unless you want to cut down, not increase your audience. With range being limited, you'd need a large number of users to need this stuff. However - if you wanted to use the radios for nefarious dodgy reasons, with encryption, you'd be better picking a frequency NOT in a public band. I've never heard of anyone buying a Baofeng 888 with the foreign frequencies in every being in trouble.