Hoosier SAFE-T Network

[mr10pt]

I reside in Lowell, Indiana, Lake County. Lake County has their own P25 P2 network, however, I have adjoining counties programmed on my 536 and sds200. I can receive the following counties to the east and southeast (Porter, LaPorte and Jasper using the a stock antenna. They are pinging towers from adjoining sites simulcast. Immediately to the south,Newton Co is a conventional system but directly south of it is Benton Co which is on the state system, and I can receive. My question is, if these counties are on the statewide system, do they "daisy chain" their way through? If so, how far out can I listen? External antenna is a Diamond Discone at about 25' elevation with LMR400 cable.

 

[DiGiTaLD]

You will only hear talkgroups that have a user's radio affiliated to the site you are listening to. However, there are limitations. For "local area" talkgroups (i.e. talkgroups belonging to a county or city agency) they are generally allowed to affiliate to sites in their home county and sometimes sites in neighboring counties - but not always. The network does not allow radios on some talkgroups to affiliate on certain sites to conserve resources.

For example, I live in Johnson County. The site I listen to is Greenwood. It allows radios on all Johnson County talkgroups to affiliate and pass traffic. However, if a radio tries to affiliate to any of the ISP District 52 talkgroups, the network denies the affiliation, as the IPSC NOC has determined that to conserve voice channels on the Greenwood site, ISP district talkgroups should not be allowed on that site as allowing them would monopolize too many resources on a regular basis to allow the local users, many of whom only have portables, to reliably use the site.

Generally speaking (I am not aware of any specific exceptions but I think there may be) the statewide mutual aid talkgroups are allowed on every site in the whole state. Regional mutual aid talkgroups (i.e. A-MA1, etc.) are allowed on sites in their region and usually the sites immediately surrounding their region, perhaps with some exceptions.

For instance, if I turn my subscriber radio on to A-MA1 where I live, despite being well in range of several sites, I will get an "OUT OF RANGE" on the display, since none of the sites in range of my radio will allow me to affiliate on A-MA1 here in region H.

Hope this makes some sense!

 

[mr10pt]

Well written, totally understandable. Thank you!

 

[speedway_navigator]

I'm assuming if a Johnson county unit were to cover a state unit he/she would switch to a mutual aid TG since they can't get on 52's.
I hear state units on Hendricks law dispatch so I know they can talk to us.

 

[usswood]

correct, SP and most nearby county/city radios can affiliate to that nearby county/city areas talkgroups and vise versa... Now as for their primary talkgroup affiliating with a certain tower outside their county, this is where a radio might get an OUT OF RANGE response. I see that on our downtown tower a lot, Sullivan County can affiliate to the South County tower but not our downtown tower. However our downtown tower was county funded also! Heck, IDOT can't even affiliate with our downtown tower.

 

[vocoder]

So on a 5 site safe t simulcast, can 1 single site, out of the 5 networked simulcast sites, be programmed or selected?
If so, how does this work? I ask, because all sites use the same frequencies and NAC.

Thanks
73

 

[mr10pt]

Another question for this thread. I monitor 5 surrounding counties on this system. I have them programmed individually in my FL with FLQK's assigned using location control for ease of operation. I have monitored each and avoided sites that do not have any activity. Is this the correct way to program these or, do I set up the "system" and assign number tags for each dept? Using Sentinel software for a 536 and sds200.

 

[speedway_navigator]

@vocoder
I'm not a P25 expert but I think the ability to deny a radio on a per site basis is done using the Location Registration Area feature shown is this diagram.

Codan Radio P25 Training Guide - Manual (Page 81)

Codan Radio P25 Training Guide User Manual • Registration • Codan Radio Radio Stations

www.manualsdir.com

 

[speedway_navigator]

IDOT can't even affiliate with our downtown tower.

A tech in Terra Haute said they just about tie up a site during a big snow plowing operation.

 

[usswood]

A tech in Terra Haute said they just about tie up a site during a big snow plowing operation.

Not really sure about that, we have 8 or 9 VCs on that tower?
I have only seen one instance where all VCs were in use at the same time (this is without IDOT) and then is was only for a brief moment! LOL

 

[speedway_navigator]

He might have meant Clay county.

 

[DiGiTaLD]

I'm assuming if a Johnson county unit were to cover a state unit he/she would switch to a mutual aid TG since they can't get on 52's.
I hear state units on Hendricks law dispatch so I know they can talk to us.

I have actually seen a lot of county codeplugs that have ISP district talkgroups programmed into them. I know Boone County's and Marion County's standard law enforcement codeplugs have ISP 52 district talkgoups. I've never heard any agency other than ISP on the district talkgroups. Its probably frowned upon and better to use mutual aid.

Certainly the ISP codeplugs have local agency talkgroups as I hear troopers fairly regularly on both Johnson County's IPSC talkgroups as well as IMPD district talkgroups on the DPSC system. I've never looked at an ISP codeplug so I don't know if they vary district to district or not. I wouldn't be surprised if they have a codeplug that covers the whole state since there is always the possibility of them having to go anywhere to help out.

 

[DiGiTaLD]

So on a 5 site safe t simulcast, can 1 single site, out of the 5 networked simulcast sites, be programmed or selected?
If so, how does this work? I ask, because all sites use the same frequencies and NAC.

Thanks
73

In a simulcast cell, the subscriber radio sees all of the physical sites in that cell as one site. So no, you cannot select a single site inside a simulcast cell. Your best bet in that case is a directional antenna pointed at the site nearest to you, which will hopefully provide a clean enough signal for good decode (many scanners are not good at this).

In a good simulcast cell, such as Indianapolis-Marion County's DPSC system, each repeater at each site is synchronized precisely using GPS timing and highly reliable microwave backhaul links to transmit on the same channel pairs at precisely the same time, and the antenna patterns at each physical site are optimized with consideration to all the other sites in the cell to provide the best possible coverage inside the cell's target coverage area, which in this case would be Marion County. When a simulcast cell is tuned and optimized well, such as the DPSC system is, it really provides awesome coverage. With P25 simulcast, timing is everything.

 

[AK9R]

In a good simulcast cell, such as Indianapolis-Marion County's DPSC system, each repeater at each site is synchronized precisely using GPS timing and highly reliable microwave backhaul links to transmit on the same channel pairs at precisely the same time...

And, those microwave links between tower sites date back to the original MECA 800 MHz system, though I'm sure the equipment has been upgraded since then. There was a very precise clock, made by Ball Corporation, in the basement of the "MECA building" at State and Washington. The time signal from that clock was sent out to the remote sites via microwave via two loops, one clockwise around the county and the other counterclockwise. The time signal at each site was adjusted to compensate for microwave propagation delays and then used to synchronize the transmitters. As a result, you almost never heard the "heterodyning" that you'd normally get from receiving two analog signals on the same frequency. There were two loops to provide redundancy--if one path was broken, the signal could use the other path.

 

[INDY72]

Yes, the entire backhaul is being redone as part of the upgrades to S1, and S2. That is in addition to phase in of the APX radios replacing all the older XTS series for Public Safety, and eventually Public Works/Operations. As well as other hardware upgrades, and going to the newest ASTRO-25 firmware over this year. The only way radios can select a single repeater on the simulcast systems, is talkaround, and/or failure of trunking and they have to revert to using individual towers as conventional sites. And the ultimate final fall back is to go to analog. And yes, all IDPSC codeplugs also have SAFE-T and all the surrounding agencies TG's for interop. All surrounding agencies also have IDPSC in their radios. ISP can, and does have full permission to jump on IDPSC TG's, and other SAFE-T TG's for interop, but local LEA's are not allowed to jump on ISP TG's. SWMA's. Regional MA's, and Zone Event TG's are there for use if needed. SWMA's are open on all but DOC sites. Zone Events are locked for North (1), and South (2). Regional are locked to areas. And yes, there are some TG's literally locked to 1 site only.

 

[INDY72]

To see an template of the IFEMS set up, hit me up and I will e-mail you it.

 

[speedway_navigator]

The time signal at each site was adjusted to compensate for microwave propagation delays and then used to synchronize the transmitters.

Way back in the late 80s I was working for the Motorola service center in San Diego. One tech had to go to Otay mountain to do some repairs and a visiting Moto engineer from Schaumburg asked to tag along to see our site.
The tech had to replace a board in a simulcast paging xmtr and was showing the engineer the process.

When Bob pointed out the timing delay box the engineer asked why we needed to delay the signal, poor guy had no clue how simulcast worked.

 

[usswood]

Vigo officers (city and sheriff) and surrounding counties all have DISP 53 in their radios and do use it when coordinating pursuits or highway shut downs

 

[DJ11DLN]

Vigo officers (city and sheriff) and surrounding counties all have DISP 53 in their radios and do use it when coordinating pursuits or highway shut downs

I hear ISP on all of the area locals fairly frequently, not just Vigo/Terre Haute. It seems to work pretty well for all concerned and is a lot more seamless than trying to meet up on one of the MA TG's. Likewise units from the adjacent County will jump on too if there's a pursuit or something of that nature so evidently they all have at least the surrounding County Dispatch and Ops TG's as well.