Indiana canceling DOT Low Band Licenses

[alphabravo1]

Just noticed, a bunch of cancellations came through for the old low band 47 MHz frequencies.

I guess they feel they no longer need a back up. Hope they're right.

[GTO_04]

I can't remember the last time I've heard them on low band. How long has it been?

GTO_04

[KC0QNB]

They must be real confident in their "new"system, personally I think it is a bad idea, one good ice storm and the new system may go to pieces, where on the other hand low band works period, has for years. They will reconsider if one of their plow drivers gets stuck and can't talk to anyone.

[alphabravo1]

Originally Posted by GTO_04

I can't remember the last time I've heard them on low band. How long has it been?

GTO_04

Around here, southern Indiana, they used it infrequently.
However, if two towers for safe-t go down... they will have trouble communicating.
Not to mention they jam up several groups with meaningless chit-chat...
I.E. high tech CB system. That could be fixed with a priority and training.

[Radio_Cowboy]

They have already pulled all the Lowband radios and antenna's from the trucks, and surplussed them out ( I saw some of the radios ended up on Ebay a while back), so I guess they figure no point in keeping the licenses active any longer. I drove past the old Vincennes yard at the north end of town, and the lowband dipole array is still on the tower, but probably not connected to anything any longer. Since IDOT Vincennes moved to the new building at the south end of town, the old north complex is all gone now. Only thing left is the tower!

[davidwild]

Ever since the flooding, I've heard a lot of DOT-52-SUB traffic on the Bloomington tower. Particularly, I've heard what sounds like flaggers directing traffic. I would have thought simplex would have been better for this, but I guess they don't want to have more than one radio, and 800MHz simplex isn't really used as far as I'm aware (although SAFE-T does have some simplex frequencies)

David

[alphabravo1]

Yes the flaggers use it a lot, but through the repeater. And we are talking feet in distance.
In Scottsburg they dismantled the tower. Dumb idea... why not keep that for emergency use. They already own and won't have to get permission to use it if say a safe-t tower goes down.

Or even hook up a CB radio to them for reporting potholes. They can't seem to find and fix them, at least people could call these in.

[kadetklapp]

ISP of course ripped out all Low Band stuff. Stupid if you ask me. Kinda like local dispatches not monitoring ILEEN, Plan-A, and Point.

Twice in the last month while I was on duty the Boone County Simulcast went down and both times I couldn't get thru on Plan-A since it was "turned down" on the console. Had to call on my cell (MDTs were down as well) and ask them for a radio check on plan-a.

[DiGiTaLD]

Originally Posted by davidwild

Ever since the flooding, I've heard a lot of DOT-52-SUB traffic on the Bloomington tower. Particularly, I've heard what sounds like flaggers directing traffic. I would have thought simplex would have been better for this, but I guess they don't want to have more than one radio, and 800MHz simplex isn't really used as far as I'm aware (although SAFE-T does have some simplex frequencies)

800 simplex would be perfect for flaggers. They could use one of the ITAC channels in direct mode or the statewide talkaround channel (855.2375 PL 192.8). The only time I have ever heard that channel used was by several police officers working what I think was a local football game. Couldn't have been too far away from me because I was hearing it on my 2096 with just the 800 MHz rubber duck.

It all comes down to lack of education and training. These guys apparently do not understand that they are tying up precious system resources and infrastructure by chit-chatting on their talkgroups or using talkgroups on the system for traffic that could be just as easily passed on conventional simplex - and the radios do have that conventional simplex programming - it's just that nobody knows what it is or how to use it.

IMO, Indiana will be in a sorry state of affairs when the defecation hits the rotary oscillator and SAFE-T goes down at the same time. Its one thing to have workarounds set up, but its another thing entirely to actually 1)know that they exist, 2) know what they are, and 3) know how to use them. Many users of this system are so addicted to infrastructure, and when it goes down it seems that most of them have no idea what to do.

[Viper43]

I don't think you give them enough credit, several times SAFET towers have gone down leaving a lot of users to find other ways to communicate and they have always had a backup, and when Martinsville flooded all the PD got was busy signal and they switched over to a backup system for all fire and PD.

V

Originally Posted by DiGiTaLD

IMO, Indiana will be in a sorry state of affairs when the defecation hits the rotary oscillator and SAFE-T goes down at the same time. Its one thing to have workarounds set up, but its another thing entirely to actually 1)know that they exist, 2) know what they are, and 3) know how to use them. Many users of this system are so addicted to infrastructure, and when it goes down it seems that most of them have no idea what to do.

[nascargrant]

Originally Posted by DiGiTaLD

800 simplex would be perfect for flaggers. They could use one of the ITAC channels in direct mode or the statewide talkaround channel (855.2375 PL 192.8). The only time I have ever heard that channel used was by several police officers working what I think was a local football game. Couldn't have been too far away from me because I was hearing it on my 2096 with just the 800 MHz rubber duck.

It all comes down to lack of education and training. These guys apparently do not understand that they are tying up precious system resources and infrastructure by chit-chatting on their talkgroups or using talkgroups on the system for traffic that could be just as easily passed on conventional simplex - and the radios do have that conventional simplex programming - it's just that nobody knows what it is or how to use it.

IMO, Indiana will be in a sorry state of affairs when the defecation hits the rotary oscillator and SAFE-T goes down at the same time. Its one thing to have workarounds set up, but its another thing entirely to actually 1)know that they exist, 2) know what they are, and 3) know how to use them. Many users of this system are so addicted to infrastructure, and when it goes down it seems that most of them have no idea what to do.

There is alot of truth in what you are saying. It seems as if Greenwood Fire is the only agency in Johnson County that actually uses the Tac channels.

[DiGiTaLD]

Originally Posted by Viper43

I don't think you give them enough credit, several times SAFET towers have gone down leaving a lot of users to find other ways to communicate and they have always had a backup, and when Martinsville flooded all the PD got was busy signal and they switched over to a backup system for all fire and PD.

For some agencies, this may be true, but for others, it definitely is not. Many are either voluntarily scrapping their fallback systems (INDOT for example, or ISP pulling out their low band gear as another example) or letting their old systems fall into such states of disrepair that should they have to fall back on those systems, their reliability will be in question.

My point is that SAFE-T is an infrastructure-intensive system that works great when it works, but its far too dependent on terrestrial data lines that are likely prone to the same infrastructure failures that would impact other terrestrial modes of communication when a disaster happens. Radio should be more or less immune to terrestrial communications failures, but we've now come full circle in building radio systems that are highly reliant on those terrestrial communications systems. Without T1s, SAFE-T is just a bunch of free-for-all standalone trunking sites with no interconnectivity.

[davidwild]

So now I'm interested in what happens when T1 lines go down.... I assume that a site which is cut off from the rest of the SAFE-T world continues to function, but will not receive simulcasts nor broadcasts from radios affiliated to other sites? What happens if half an agency's radios are affiliated with one tower on the network, and the other half with a tower off the network?

David

[DiGiTaLD]

Originally Posted by davidwild

So now I'm interested in what happens when T1 lines go down.... I assume that a site which is cut off from the rest of the SAFE-T world continues to function, but will not receive simulcasts nor broadcasts from radios affiliated to other sites? What happens if half an agency's radios are affiliated with one tower on the network, and the other half with a tower off the network?

David

David,

When a T1 goes down, the site goes into what's called site trunking, and all radios affiliated with talkgroups on that site lose all communication with radios affiliated to that same talkgroup on other sites still connected to the zone controller (or sites also disconnected from the zone controller). When a site goes into site trunking, wireline consoles in dispatch facilities that are connected via leased line to the zone controller are also unable to use the site in site trunking for any communications, because they have no way to connect with it. Additionally, subscriber radios can detect when site trunking is occurring via data sent on the control channel, so users will not be totally in the dark as to why they cannot communicate with everybody on their talkgroup. Provided the functionality is programmed into the radio, a user can actually press one of the radio's buttons and scan for another site to affiliate with. A SmartZone site in site trunking basically operates as a standalone trunking system, and it also becomes a free-for-all site, as described below.

When its connected to the zone controller (ZC for short), the site follows all the rules set out in the ZC's subscriber access control (SAC) database. The SAC database defines which radios are allowed on which talkgroups, and which sites those radios and talkgroups are allowed to affiliate with and pull traffic through. This is a smart way of conserving system resources so you don't have a radio from (as an example) Lake County get taken down to Posey County by it's owner, and pull a bunch of traffic on Lake County talkgroups through the site in Posey County, thereby hogging up the resources on the tower that radios operating on that site in Posey County need for their primary talkgroups. The system is statewide, yes, but outside of certain talkgroups defined in the SAC database, not all talkgroups are allowed on all towers statewide. The exception to this rule is the statewide mutual aid talkgroups and the other talkgroups that are explicitly defined as being allowed to function on any site in the state.

Enter site trunking. The full SAC database isn't stored locally at the individual trunking sites. When a site loses it's link to the ZC, it becomes more or less free-for-all, and radios on talkgroups that ordinarily wouldn't be allowed on that site are allowed, however it doesn't really matter, because you can't pull traffic from other sites in the system if there is no link to the ZC in the first place. It could potentially still create havoc for users trying to use the site in site trunking mode if too many users from out of the area have radios affiliating and are also generating traffic on the site. That's probably unlikely to happen, though, but theoretically possible.

Hope that was understandable enough to comprehend. The fact that the system is highly dependent on terrestrial communications lines is a major reason why fully functional backups should be maintained and regularly tested by all agencies using the system.

[Viper43]

Not confusing enough yet..... add in priority levels too.... :-)

Just kidding of course.....

V

[delallen]

Originally Posted by DiGiTaLD

David,

When a T1 goes down, the site goes into what's called site trunking, and all radios affiliated with talkgroups on that site lose all communication with radios affiliated to that same talkgroup on other sites still connected to the zone controller (or sites also disconnected from the zone controller). When a site goes into site trunking, wireline consoles in dispatch facilities that are connected via leased line to the zone controller are also unable to use the site in site trunking for any communications, because they have no way to connect with it.

As usual from DIGIaLD that is a great insight on how this system works.

Thanks for educating some of us with "Safe-T for Dummies"

Great job...

[KLH]

Originally Posted by DiGiTaLD

David,

When a T1 goes down, the site goes into what's called site trunking, and all radios affiliated with talkgroups on that site lose all communication with radios affiliated to that same talkgroup on other sites still connected to the zone controller (or sites also disconnected from the zone controller).

Thanks, I've always wondered what "Site Trunking" means. I've heard it refered to alot in Knox county. Especially anytime there is a storm. Actually any time there is a storm, all the radios go into "Site Trunking" mode and central dispatch is left in the dark, unable to recieve any radio traffic.........

[davidwild]

Thanks for the detailed answer DigitalD, this is fascinating! I wonder if we'll ever get to see how it all works out in practice...

David

[DiGiTaLD]

Originally Posted by Viper43

Not confusing enough yet..... add in priority levels too.... :-)

Yeah, I guess I forgot about those. Glad you guys were able to understand my post. Something else that may interest everybody is that in a SmartZone system, when sites are connected to the ZC as they normally would be under normal operation, none of the audio is repeated locally at the tower site.

In a standalone trunking system (or a conventional repeater system) audio is received by a repeater's receiver section on the input channel (on 800 MHz that's 45 MHz down the band from the channel we listen to, the output channel) and then retransmitted by the repeater's transmitter section on the output channel. In SmartZone operation, however, it gets a lot more complicated. Audio is received by a repeater's receiver section at a site. It is then sent via T1 to the ZC site and through a switch called an Ambassador. The Ambassador's job is to distribute that audio to all the sites a talkgroup is affiliated with, and the ZC will arrange for a channel grant and transmission of that audio on all the sites the talkgroup is affiliated with. The audio is sent again via T1 out to all the sites the talkgroup is affiliated with, including the originating site, and transmitted by the originating repeater's transmit section (and the transmit sections of repeaters at all the other sites the talkgroup is currently affiliated with).

Even if there are only a few radios on one talkgroup and they are all affiliated with and operating on the same site and only that site, the audio still has to take the long trip from the repeater's receive section all the way to the ZC site and the Ambassador switch and back to the repeater's transmit section before it ever gets on the air. It's pretty remarkable that this happens seamlessly thousands of times a day. Every transmission that occurs on SAFE-T that is not on a site in site trunking mode works this way. When you get into operation between zones (i.e. between North Zone and Southwest Zone), the Ambassador switch for North Zone pipes the audio from a talkgroup with radios affiliated to sites in it's zone to the Ambassador switch in the in Southwest Zone where radios are affiliated to sites and are on the same talkgroup as radios in the North Zone. The ZCs in both zones make arrangements for channel grants on the appropriate sites to which a TG is affiliated, the audio is sent and received via the Ambassadors, and that's how statewide communication is possible. The great majority of this takes places over the T1 lines. I understand that there are a few microwave links in the system, but loss of T1s will wreak havoc nonetheless.

Of course, when a site loses it's link to the ZC and the Ambassador switch, it reverts to site trunking mode, and all the audio is repeated locally at that site, all in the same box more or less. Its a lot simpler, but then there is no communication with any of the other sites on the network.

You can think of SAFE-T as basically a big old VoIP wide-area network between a bunch of trunking sites.

[powerlineman]

I'm not sure when it happened but I noticed last week that the Petersburg INDOT tower has been removed.