DMR Multi Frequency

[sibbley]

Mods, please move if there is a better forum for this. Here is my question of the day.

Why would a business use multiple frequencies in a conventional sense instead of Con+ or CAP+ for DMR?

A bit of background: A system I will call conventional DMR. 21 frequencies VHF and UHF. Talk Groups move between the frequencies as if the system was trunked. As you can see below I logged the same TG on 3 frequencies in the span of 20 minutes.

04-12-18 14:42:26 - 463.9000 CC 2 TGID:42
04-12-18 14:52:26 - 464.0750 CC 2 TGID:42
04-12-18 15:09:03 - 451.8500 CC 2 TGID:42

I know who this TG belongs to, so I know each recording for each of the above frequencies was the same TGID. There are other TGID's on this system that also move between the frequencies. None of the frequencies ever show anything other than DMR. I have never found a control channel or home channel on any of the licensed frequencies. The TGID's could be broadcast on any of the VHF or UHF frequencies.

I'm just trying to figure out how this system works.

Thanks

 

[Ubbe]

Do you hear anything on the frequencies in locked analog FM mode that sounds like a periodic data burst that could indicate control data? One frequency DMR channels sends out beaconing in one minute or longer intervals but control data is sent 1-10 seconds intervals.

Amateur DMR sites are network linked and are a single frequency setup and the transmissions are copied and mirrored on several sites. You can then use cheap non trunked DMR radios on a system with big coverage using a standard scanning list. Maybe your system are run by cheapskates?

/Ubbe

 

[sibbley]

The only time I hear anything on each frequency while locked analog is during voice transmissions confirmed using the 436 (analog) and 536 (OFT). The frequencies are licensed by a cable company, so it could be network linked. They also could be cheapskates.

I have never confirmed if the transmissions were mirrored over all or several frequencies. I guess that will be my next course of action.

I do have a hospital with several locations in my area that operates this way. Security is mirrored over 4 frequencies and Maintenance is also mirrored over 4 frequencies. They do use cheaper Vertex EVX-534 radios.

Thanks

 

[sibbley]

Well, thanks for the insight Ubbe. I setup two scanners programmed the same with the user's frequencies. I can confirm the transmissions are mirrored.

 

[crazyboy]

Ip Site Connect with subscribers programmed for roaming.

 

[sibbley]

Ip Site Connect with subscribers programmed for roaming.

Awesome, Thank you. I was not familiar with IP Site Connect.

 

[sibbley]

Seems reasonable why IP Site Connect was chosen. A cheaper alternative for the needed wide area coverage for this particular user. Since they are also an Internet Provider, I imagine their cost was even better than average.