ARMER Question 396XT

[ofd8001]

I think I got a fairly good handle on the ARMER system, listening to it quite a bit while on vacation last week. I know that radios have a "home" system, but if the radio is away from the home system it may affiliation with another system.

A question came to mind while I was scanning the Minneapolis North Side system (which I think is the Minneapolis system), the Minneapolis City center system (for state units), Hennepin East and Hennepin West.

I hit the hold button on my 396XT with a Minneapolis PD TG showing on the Hennepin East system. So I'm presuming an MPD unit affiliated with the Hennepin system as it was better suited for reception. I wondered if no MPD units were affiliated with the Hennepin system, would the scanner go back to the Minneapolis system?

I suppose this is a long winded way of asking that with a 396XT holding on a talkgroup, is it holding on the talkgroup regardless of site, or is it holding on both the site AND the talkgroup?

Thus if I want to listen to MPD, would I have to be sure I'm holding on the Minneapolis city system and the desired talkgroup?

 

[mrhowes]

ARMER Question....

The quick answer is, if you are holding on an MPD talkgroup, via Hennepin East tower (site), then yes you would continue to monitor that MPD TG via Hennepin East only. It would not then monitor other sites (State City Center, Ramsey, Minneapolis N/S, etc) for traffic for that MPD TG.

Ideally if you want to monitor most (if not all) Minneapolis TG's the best site to use would be the Minneapolis site. In the same way, the best site to monitor State Patrol TG's in the Metro, as well as other metro based state agencies, would be State City Center. And so on and so on for Ramsey, Hennepin, and Anoka county, based agencies, matching the respective sites (Ramsey, Hennepin East/West, Anoka).

Now for the rub, and where it can get a bit confusing. Note that above, I have used the word "Best", and not "only" when matching up a set of agencies and a site. The reason for this is because it is possible to hear TG's assigned to a certain county based agency while monitoring a site(s) located in different a county or counties. For example I have been able to hear Ramsey East (Law) and Saint Paul (PD/FD) TG's while monitoring the Hennepin East site. This has happened with other TG's and sites as well. This does not mean, however, that you can hear all metro agencies while monitoring say a Hennepin site. As of yet I have not figured out the rhyme or reason why you can hear some TG's on one site, but not on other sites.

I have noticed one thing though. I might be able to hear Saint Paul Dispatch (FD/PD) while monitoring Hennepin East or State City Center, but other non-dispatch TG's (Car-to-car, Fireground, Special Events) are not likely heard. The same seems to happen with Hennepin county TG's on sites other then Hennepin sites. For example, I might hear Richfield FD dispatched to a large fire while monitoring the Ramsey site, but I will not hear their fireground TG via that same site. I would most likely have to be monitoring a Hennepin County site to hear that Fireground TG.

So again, the BEST course of action is to monitor the county/state site related to the agency you with to listen to. ( Hennepin TG's<<>> Hennepin East/West sites Ramsey TG's<<>> Ramsey Site, etc).

I hope I have not made this more confusing.

 

[ofd8001]

Thanks - that's what I was thinking and wanted to confirm.

As far as hearing some talkgroups on some sites, but not other talkgroups on the same sites, I believe it has something to do with affiliation privileges. I saw somewhere on the 'net a list of what talkgroups are allowed or denied to affiliate with which sites.

They probably have exerted some control over what affiliations are allowed or denied to avoid tying up channel resources. I remember reading a report on the ARMER performance during the bridge collapse. Some distant locations had units listening to the active talkgroups in Minneapolis (the law tac channels I believe), which tied up voice channels at the distant locations. That led to some "bonks" when others tried to use the remaining channels at the distant locations.

I understand that for a given site to "host" a "foreign" (best words coming to mind) talkgroup, there has to be a user affiliated with the "foreign" talkgroup in the site's area.

This might not be a great example because I don't know the specifics of the system, but here's one that comes to mind. An Anoka fire unit happens to be in St. Paul and has his radio set to Anoka Talkgroup 1. Anoka talkgroup 1 may be heard on the Ramsey simulcast site, as long as that unit is in St. Paul. The "link" shuts off whenever that user leaves the area. Also Anoka Talkgroups 2 to whatever won't be heard because the radio isn't set on the other talkgroups.

That's the best understanding I have on SmartZone OmniLink setup, that is used in Minnesota along with many other multi-site systems.

 

[mmtstc]

Most public safety talkgroups have limited Roaming capabilities, so Police and Fire can access their home systems and their surrounding systems (Anoka radios should be able to roam onto HEast, HWest, CCenter, Ramsey, Sherburne and Isanti on their Main talkgroups. Generally public services and local talkgroups are limited to the home system only. EMS radios are considered nomadic, so they often can roam where ever they choose and have privileges.

All agencies should have access to a roaming talkgroup for their county which does have statewide roaming privledges, but they are rarely used. Statewide tactical talkgroups also add a dynamic as radios are allowed to affiliate with those talkgroups outside of their home system, btu this is psecific to LSCRAM, LESIU, LTac, ETac, FTac and STac.

 

[WA0CBW]

That is pretty much how it works. When systems are connected a radio affiliates with a site and tells the site what talk group it is on. That site talks to the master site and says I have a unit here on one of your talk groups, please send me the audio for that talk group. As long as that unit is affiliated to that site that talk group audio will appear on that site. If that unit shuts off the radio or leaves that site or de-affiliates then that particular talk group audio is not sent to that site.

So you will not hear a talk group audio unless there is a radio(s) affiliated to that site on that talk group. There are some exceptions depending on how the system(s) talk group audio is distributed.

BB