dPMR446 traffic USA?

[Lscott]

Well I just got a clean looking license free TK-3701D dPMR446 radio, NOT DMR446, which is the other allowed digital mode. The idea is to run some tests between it and the Icom's I have with the more functional dPMR digital voice mode. I want to see if they will communicate. There are some slight differences that might bugger it up. I won't know until I can get around to running some tests.

Other thing there radios are the functional equivalent of FRS here, but in the EU where it's license free, 0.5 watts, and digital voice is allowed. 

I'll bet some Ding-Dong will bring their radios here on vacation and try to use it while at some major tourist attraction like Disneyland, Yellowstone etc. The radios only work from 446.0000 to 446.2000, the Ham 70cm band.

Anyone ever bump into something like this on the air? If one has a spectrum analyzer, or SDR, it would look like the ultra narrow band NXDN mode, the modulation is the same but the digital protocol is different.

https://kenwoodcommunications.co.uk/files/file/comms/uk/brochures/TK-3701D_20191030_LR.pdf

https://kenwoodcommunications.co.uk/files/file/comms/uk/pmr446/PMR446-White-Paper-V6_18AUG2016_JT_KB.pdf

[WRYS709]

Are there any “legitimate” domestic (US) uses for this radio?

[Lscott]

6 hours ago, WRYS709 said:

Are there any “legitimate” domestic (US) uses for this radio?

Yeah, works on the Ham band. Would be a novelty. Without another compatible radio, or decoder for an SDR, good luck monitoring the digital voice traffic. Almost as good as encryption but since it’s publicly documented the FCC can’t really complain it’s a “secret code” thus illegal on the Ham band.

The point to remember is the modulation used is exactly the same as the low data rate NXDN mode. The later the FCC has emission designators for that. You can’t tell the difference with a spectrum analyzer. What’s different is the CAI, common air interface a.k.a. the digital protocol used.

Note the radio is restricted to just the official dPMR446 frequencies in self programming mode. The radio programming software is also locked to the same frequencies.

My main objective was to do some testing to see if it will communicate with a full feature dPMR radio. I have some Icom dPMR radios. There are a few “slight” differences which might bigger that up. There are in fact two different ETSI standards, one each, for the two, dPMR446 verses dPMR.

https://forums.mygmrs.com/gallery/image/500-ic-f3162dt-front-and-back-sidepng/?context=new

 

[WRYS709]

Reminds me of the Cotre C001D DMR HTs that were briefly available from Amazon for $17 and actually worked!

[Lscott]

4 hours ago, WRYS709 said:

Reminds me of the Cotre C001D DMR HTs that were briefly available from Amazon for $17 and actually worked!

This radio was a bit more expensive, GBP 90. I had it shipped from the UK through eBay's international system.

https://www.ebay.com/itm/126800820122?var=427899179724

I had to get it before the "de minimus" tariff exception for goods under $800 disappears on 8/29/2025. Otherwise it would be a ridiculous price with the minimum tariff required. No more shopping for stuff outside the USA on eBay anymore.   

https://www.avalara.com/blog/en/north-america/2024/11/de-minimis-exemption-changes-coming.html

[jwilkers]

This radio was a bit more expensive, GBP 90. I had it shipped from the UK through eBay's international system.
https://www.ebay.com/itm/126800820122?var=427899179724
I had to get it before the "de minimus" tariff exception for goods under $800 disappears on 8/29/2025. Otherwise it would be a ridiculous price with the minimum tariff required. No more shopping for stuff outside the USA on eBay anymore.   
https://www.avalara.com/blog/en/north-america/2024/11/de-minimis-exemption-changes-coming.html

DPMR 446 operates in the 70cm amateur band in the USA. An amateur radio license is required to operate there.

Sent from my SM-S911U1 using Tapatalk

[Lscott]

Just now, jwilkers said:

DPMR 446 operates in the 70cm amateur band in the USA. An amateur radio license is required to operate there.

Yes I know. That's one reason I got it because I can use it on the Ham band. The other is to see if I can get it to communicate with a couple of Icom dPMR radios. Doing the experimentation on 70cm is legal so long as i properly ID. 

There are a few differences between dPMR446 and the full featured dPMR.

1. dPMR446 uses the concept of a "common ID", whereas dPMR uses a "dialing" address, 24 bits, that functions as a Talkgroup and user ID depending on the range set for the ID. The remainder of the range is interpreted as the Talkgroup. You want a larger range for ID's, you have less range for Talkgroups. 

2.  The CC, channel code, for dPMR446 is a fixed value depending on the channel frequency. There are only 16 unique codes, listed in a table in the dPMR446 standard document, that would be used. For dPMR the CC is calculated based on an algorithm that uses the frequency, and there could be up to 64 unique codes. Using that algorithm for dPMR with the dPMR446 frequencies you don't get the values listed in the table for the dPMR446 standard. 

Otherwise the two are the same protocol.

Number 1 I did some calculations and can generate the required bit pattern for the "common ID" using the dPMR Talkgroup/ID. However I can only generate a valid Talkgroup/ID for about 222 out of the 255 "common ID codes"

Number 2 I think is going to screw things up where the communications will fail. I suspect this was done to prevent someone, like me, from attempting to use a commercial grade dPMR radio on dPMR446. I guess that's why there are two standards.

Mathcad - dPMR446 Common ID Cod.pdf Channel Codes Edited ETSI TS 102 658 V2.6.1 (2019-01).pdf