DMR (TDMA) 446

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
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gmham
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Re: DMR (TDMA) 446

Post by gmham » 30 Jan 2017, 07:54

okay cheers guys got it now.
I take it on analogue there is no scrambler on the Tyt md380 ?
.... Icom IC7300 - 2x Cobra 148gtldx Mk2 / Sommerkamp ts788dx / Ameritron ALS-600X - Cushcraft r6000 HF vertical / 80-10 mtr ocf dipole / Astatic 575m6 mic / Heil ICM mic.

108-TM-154 - John

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Re: DMR (TDMA) 446

Post by radiosification » 31 Jan 2017, 11:52

Admiral wrote:In theory you don't need a contact name if you have a defined grouplist.
I know, but that's for receiving. If he is trying to transmit then you need a contact name unless you go into the contacts list manually every time you want to push the PTT. I have found that on the TYT MD-380 at least, if you transmit with no contact set, in certain circumstances, it will transmit an empty carrier that just goes on and off. It could be the same thing happening on gmham's radios.
gmham wrote:okay cheers guys got it now.
I take it on analogue there is no scrambler on the Tyt md380 ?
That's correct there is no analogue scrambler, but there is digital encryption which is far more secure if you need security.
If you're interested in digital voice, check out my YouTube channel:
http://www.youtube.com/radiosification

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Re: DMR (TDMA) 446

Post by gmham » 31 Jan 2017, 12:50

As always thanks again for the info! All working now!
.... Icom IC7300 - 2x Cobra 148gtldx Mk2 / Sommerkamp ts788dx / Ameritron ALS-600X - Cushcraft r6000 HF vertical / 80-10 mtr ocf dipole / Astatic 575m6 mic / Heil ICM mic.

108-TM-154 - John

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Re: DMR (TDMA) 446

Post by gmham » 01 Feb 2017, 12:51

Sorry guys back again .. knew it wouldnt be long !!

okay digital 446mhz tests are great and must admitt to being very impressed with the range / audio !

okay if I am monitoring my dmr 446mhz freq and another one off my programmed channels comes on air ( shopwatch ) it automatically switches to this shopwatch freq. going back to the programming software how do I keep just my dmr 446mhz channels seperate as to prevent this happening ?
.... Icom IC7300 - 2x Cobra 148gtldx Mk2 / Sommerkamp ts788dx / Ameritron ALS-600X - Cushcraft r6000 HF vertical / 80-10 mtr ocf dipole / Astatic 575m6 mic / Heil ICM mic.

108-TM-154 - John

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Re: DMR (TDMA) 446

Post by Admiral » 01 Feb 2017, 20:09

Make separate zones and set different scan groups for each zone.
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Re: DMR (TDMA) 446

Post by bigbloke » 25 Apr 2017, 13:51

part of the encryption challenge is that for some chinese DMR radios with "enhanced" privacy
the key length is 72 bits (e.g. CSI) unlike the MD380 which is 128 bits.

When testing 446 do it in the clear and confirm that it works - then and only then enable enhanced encryption!

of course if both radios are the same then happy days

regards

BB

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Re: DMR (TDMA) 446

Post by bigbloke » 16 May 2017, 13:51

Admiral wrote: It's virtually impossible to listen in on fully encrypted DMR on any band, GCHQ wouldn't be able to earwig without the keys.
agreed - but conversely they can crack the keys in minutes - even the 128 bit ones - as far as I know even AES256 is considered
vulnerable after 2020!

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Re: DMR (TDMA) 446

Post by radiosification » 16 May 2017, 16:43

How can they crack the key in minutes? Is there a backdoor built in?
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Re: DMR (TDMA) 446

Post by Admiral » 16 May 2017, 16:57

This is out of my thought process, but a guy in our group claims that it would take the fastest computer on Earth at 93 PFLOPS up to 5 billion years to crack 128bit aes encryption, and 256 would be close to infinity to crack until computers get a tad quicker. I have to take his word for it.
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Re: DMR (TDMA) 446

Post by paulears » 16 May 2017, 17:30

I somehow suspect that NONE of us know what GCHQ can do, and it's pointless speculating. If they can, they won't admit it, and if they n' they won't admit that yet. However - I personally find it unlikely that our Government would allow the use and promotion of consumer price secure communications. History suggests that being able to read messages that users believe are totally and utterly secure is by far the best way forwards.

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Re: DMR (TDMA) 446

Post by radiosification » 16 May 2017, 17:36

I would guess that truly secure communications do actually exist, since the government is trying to implement laws that force companies to put backdoors in them so the security services can intercept and decrypt them. If they could already intercept and decrypt messages then they surely would have no need for this law, which I highly doubt the government would make unless they really needed to since it will probably be very unpopular.

I don't believe that AES128 encryption keys can be found by anyone in a few minutes or even a few years with current technology.
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Re: DMR (TDMA) 446

Post by bigbloke » 17 May 2017, 21:27

radiosification wrote: I don't believe that AES128 encryption keys can be found by anyone in a few minutes or even a few years with current technology.
Fair enough - but if you find anything with AES128 in the PDF linked below, I'll be more than amazed.

https://www.ia.nato.int/documents/cc-directory.pdf

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Re: DMR (TDMA) 446

Post by radiosification » 17 May 2017, 21:45

bigbloke wrote:
radiosification wrote: I don't believe that AES128 encryption keys can be found by anyone in a few minutes or even a few years with current technology.
Fair enough - but if you find anything with AES128 in the PDF linked below, I'll be more than amazed.

https://www.ia.nato.int/documents/cc-directory.pdf
Found one! X-Kryptor Client to PDA on page 60.
Also X-Kryptor Network Encryption Gateway & VPN Client on 61, Flagstone Baseline on page 74, Flagstone Baseline Plus, Flagstone Enhanced, BitLocker Drive Encryption™ on page 130. I think that's all.
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Re: DMR (TDMA) 446

Post by BK » 23 Jul 2017, 13:30

bigbloke wrote:Well if were of a mind to comply with european groups the decision is made for us it seems:

http://dmr446.hamstation.eu/index_en.htm

makes it easier ?

regards

BB
So we're all agreed it's S1 CC1, but there still seems to be confusion regarding the TG. Hams across Europe use TG9 for local on repeaters, and in the UK this has been adopted for simplex too. There is a convention of using TG99 for simplex, but that's in the US so I'm surprised they're recommending it on a European website. I'm not sure we're any closer to agreeing a standard here.

Also, now Ofcom have gone all technology neutral and allowed any mode on any channel, should the 8 digital channels be renumbered 9-16? And do we have a DMR calling channel?

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Re: DMR (TDMA) 446

Post by gmham » 20 Sep 2017, 19:10

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?
.... Icom IC7300 - 2x Cobra 148gtldx Mk2 / Sommerkamp ts788dx / Ameritron ALS-600X - Cushcraft r6000 HF vertical / 80-10 mtr ocf dipole / Astatic 575m6 mic / Heil ICM mic.

108-TM-154 - John

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