NJICS capacity

[Markscan]

Speaking with one of my LE contacts this evening, there is a rumor making the rounds about NJICS reaching capacity in northern counties, and supposedly the state has stopped allowing agencies to transition over. I replied that I highly doubt it. Anyone else hear anything like that?

 

[Tech792]

Yes, I also heard same last year.

 

[ansky]

One would hope that the Passaic County simulcast will help to expand capacity.

 

[8000XE]

I don't believe that to be the case

 

[GTR8000]

I assume that when you say "reaching capacity" you're talking about RF channels. The maximum amount of talkgroups per system is 16,000, and the maximum amount of subscribers per zone is 64,000. They're obviously nowhere near the talkgroup limit, but I'm not sure how many subscribers are currently provisioned.

The FDMA talkgroups are what really strains RF capacity, as they hog an entire channel which could otherwise carry two simultaneous transmissions with TDMA. Necessary evil to support the traffic that is SmartX'd over from the SmartZone system, and all of the NJSP talkgroups are still FDMA because of that. Once everyone is migrated over to the ASTRO 25 system and has TDMA capability, it will help alleviate some of the traffic congestion on the busier sites/cells.

As far as simulcast cells alleviating the issue, they can actually make it worse. Simulcast cells are more spectrally efficient because you reuse the same frequencies over a wider area, rather than requiring unique frequencies at each site. However it also means that all of the subscribers in that area are now sharing a smaller number of frequencies, instead of the individual sites carrying only the necessary affiliated traffic. It doesn't take much for a few FDMA talkgroups to be active to effectively kill your RF capacity.

tl;dr The sooner they can shed the FDMA talkgroups, the better off they'll be.

 

[Markscan]

I was hoping you would reply GTR8000! If anyone knows it would be you. Thanks!

 

[lynchy135]

tl;dr The sooner they can shed the FDMA talkgroups, the better off they'll be.

Is there a reason why (other than radios not supporting TDMA) that a talkgroup wouldn’t be configured for TDMA?

 

[GTR8000]

I was hoping you would reply GTR8000! If anyone knows it would be you. Thanks!

I appreciate the sentiment, but I am not any sort of insider when it comes to the NJICS. I'm just giving some general info and facts about the ASTRO 25 system that the state is using.

 

[GTR8000]

Is there a reason why (other than radios not supporting TDMA) that a talkgroup wouldn’t be configured for TDMA?

If I remember correctly, the P25 system has the DDM (Dynamic Dual Mode) option, which means that the talkgroups will prefer TDMA mode, unless a non-TDMA radio affiliates, at which point the talkgroup will fall back to FDMA mode. That option works well when you have the majority of radios able to support TDMA, however it doesn't have any effect on the following...

By nature the 800 MHz SmartZone system is FDMA (analog included), which means they use the full FDMA channel when patched over to the P25 system. No way around that, hence the reason why there is still so much FDMA usage on the P25 system clogging up the works.

 

[lynchy135]

If I remember correctly, the P25 system has the DDM (Dynamic Dual Mode) option, which means that the talkgroups will prefer TDMA mode, unless a non-TDMA radio affiliates, at which point the talkgroup will fall back to FDMA mode. That option works well when you have the majority of radios able to support TDMA, however it doesn't have any effect on the following...

By nature the 800 MHz SmartZone system is FDMA (analog included), which means they use the full FDMA channel when patched over to the P25 system. No way around that, hence the reason why there is still so much FDMA usage on the P25 system clogging up the works.

That makes a lot of sense. I had assumed that there was some sort of IP connection from one system to another and at its simplest form you have TG X on system 1 that has a two way audio stream over to TG Y on system 2, but I guess there is more than just an audio stream being sent to each other.

Anyway, this is a little off topic. Appreciate the lesson.

 

[KevinC]

By nature the 800 MHz SmartZone system is FDMA (analog included), which means they use the full FDMA channel when patched over to the P25 system. No way around that, hence the reason why there is still so much FDMA usage on the P25 system clogging up the works.

Hmm...SmartX and transcoders maybe??? Not sure if that is possible or not though.

 

[wildbillx]

Markscan- NJOIT is at the point of limiting users right now because radio ids. Until they can remove the old radio ids "NJSP xts and xtl" they are quickly approaching the limit.

 

[GTR8000]

That makes a lot of sense. I had assumed that there was some sort of IP connection from one system to another and at its simplest form you have TG X on system 1 that has a two way audio stream over to TG Y on system 2, but I guess there is more than just an audio stream being sent to each other.

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[snapple4th]

Can confirm the same thing. As of now, limited new ID's. The purpose of the NJICS system was never intended to be a one large system for every agency to use. Some counites did not want to build out their own 700 system and the state stepped in. However, as more county 700's come online or migrate from UHF you will see local agencies be moved off this system onto these county systems which is the most appropriate and efficient way. It really is a waste to have local agencies in counties with a built-out systems on a state system and I think this practice is ending for good reason.

 

[nosoup4u]

I didn't realize that 64k was the limit on subscribers. My Unitrunker ID count right now is just under 35k users, although some of that are users still on the 800 size and have no yet migrated over. If I had to guess, there are probably another 5k of ID's that I don't have since I can only get the Hunterdon site usually. I do merge other peoples ID's from other sites on occasion, but I haven't done that in probably a year.

 

[8000XE]

FDMA will continue to hog the resources like GTR stated. Who knows, they could always “expand” capacity by adding an additional core. Guess it depends on their future plans.

 

[GTR8000]

New Jersey Interoperability Communication System (NJICS)

This way I stay out of the dog house 🏠 🐕😂

forums.radioreference.com

 

[NParkNJ]

I imagine in the future more and more agencies will be joining up in the Passaic County area. I have no confirmation of anything, but look at a few northern Passaic County towns, one being on UHF analog, and another on Lowband. Resources for lowband are harder and harder to come by, to fix and maintain as time goes by. And another agency, without saying names has had issues with its radio system for a few years now....

For anyone familiar with the area up here, you know the mutual aid contracts that are in place. So even if a town doesn’t move to NJICS, it may still want, or in some cases need access through a radio at HQ, for access to the system(assuming previous analog frequencies are scrapped, and a patch like Wayne Fire has doesn’t happen).

Maybe worth stating maybe not, things are changing up this way...albeit later than southern-located counties. In the last few years, and within the last 2 years, Oakland(yes Bergen, but neighboring Passaic County), Clifton, and Hawthorne have moved to NJICS.

At a certain point, I have to imagine they’ll need to add capacity for if/when other agencies decide to join up.

 

[GTR8000]

Well, here's the thing...when the state went to a few of the counties back in 2015/2016 (Passaic, Sussex, Hunterdon, Mercer) to ask that each county sign over their general pool 700 MHz allocations to the state so they could create these countywide simulcasts, part of the agreement was that agencies in the counties would be allowed to migrate over to the system.

At some point the state is going to have to honor that agreement, and it seems that they're right up against some limits at the moment, so something has to give.

And of course that's not even taking into account counties that have a core sharing agreement with the state, such as Union and Cumberland, who presumably have or will have thousands of users on the system.