Orange County CORNet Fire Paging TG

[GTR8000]

Please excuse my lack of knowledge, but what's the issue with p25 paging? is it Orange County specific or is there an issue with TDMA and 2-tone paging?

The issue affects all digital paging, both FDMA and TDMA, and is not exclusive to Orange. In fact it's worse with FDMA due to the older vocoder.

Essentially what it boils down to is that the vocoders (IMBE for FDMA and AMBE+2 for TDMA) cannot faithfully reproduce every tone exactly, so instead there are ranges of tones that equate to a standardized tone for that particular group/range.

• For TDMA channels, there are 91 groups, where each group covers a 31.25 Hz range
• For FDMA channels, there are 72 groups, where some groups cover a 31.25 Hz range, and some groups cover a 62.5 Hz range

Because some analog tones are spaced pretty closely together, they can easily wind up falling within the same group over digital, meaning you'll wind up with some conflicts.

Some actual examples are:

• One set of tones that are 592.5-817.5, and another set that are 589.7-799.0. Over digital, both of those A tones become 593.75, and both B tones become 812.5, so you wind up with both having the same 593.75-812.5 pair
• A set of tones that are 652.5-667.5, where both of those analog tones equate to 656.25 over digital, meaning you wind up with 656.25-656.25

There happen to be a number of conflicts like that in Orange County. In Rockland only two sets of FD pager tones conflict: Nyack and Piermont

 

[rr60]

The issue affects all digital paging, both FDMA and TDMA, and is not exclusive to Orange. In fact it's worse with FDMA due to the older vocoder.

Essentially what it boils down to is that the vocoders (IMBE for FDMA and AMBE+2 for TDMA) cannot faithfully reproduce every tone exactly, so instead there are ranges of tones that equate to a standardized tone for that particular group/range.

• For TDMA channels, there are 91 groups, where each group covers a 31.25 Hz range
• For FDMA channels, there are 72 groups, where some groups cover a 31.25 Hz range, and some groups cover a 62.5 Hz range

Because some analog tones are spaced pretty closely together, they can easily wind up falling within the same group over digital, meaning you'll wind up with some conflicts.

Some actual examples are:

• One set of tones that are 592.5-817.5, and another set that are 589.7-799.0. Over digital, both of those A tones become 593.75, and both B tones become 812.5, so you wind up with both having the same 593.75-812.5 pair
• A set of tones that are 652.5-667.5, where both of those analog tones equate to 656.25 over digital, meaning you wind up with 656.25-656.25

There happen to be a number of conflicts like that in Orange County. In Rockland only two sets of FD pager tones conflict: Nyack and Piermont

Outstanding explanation, thanks. One County I spend a fair amount of time in (not Orange) pages TDMA. There is no problem at all with TDMA paging on the Harris system whatsoever with the G5. The one exception as @GTR8000 explains is duplicates within a range.

 

[GTR8000]

The above quirk notwithstanding, paging over P25 is actually pretty impressive. When done properly (i.e. a real console encoding the tones), the vocoder actually "digitizes" the tones then recreates them on the subscriber end, so they will sound extremely clean to the ear, and alerting is quite reliable with an APX using Tone Signaling or a Unication G Series pager.

Even when a county has an analog paging simulcast, having digital alerting over the trunked system can be a good backup option in some cases, and may even provide better coverage in some areas the simulcast might not have great coverage in or have the same in-building penetration that a 700/800 would (especially if paging is VHF instead of UHF).

But again, when there are known tone conflicts, those limitations need to be fully understood before anyone tosses their Minitor in the trash or relies fully on digital paging. I believe this was the biggest issue in Orange, that within a few days of the testing of TG 4616 commencing, there was already an announcement on Facebook from one of the local radio guys that he was ready to start selling G4/G5 pagers basically that same day. 🤦‍♂️

 

[GTR8000]

Fire Paging TG 4616 is back on the air, along with EMS Paging TG 3718. Enjoy.

 

[N2ACF]

Fire Paging TG 4616 is back on the air, along with EMS Paging TG 3718. Enjoy.

Thank you for the information! Now that the two paging talk groups are back on, I'm going to resume selling a few bridges that will decode all of the tones even though they're being encoded in TDMA. Right now, I have the Throgs Neck and the Newburg-Beacon for sale. Again, both bridges fully decode all of the tones regardless of analog or TDMA. If anyone is interested in one of these bridges, please contact me directly!

 

[62Truck]

If anyone wants to buy a Unication pager for these new talkgroups, I highly recommend Phil W2LIE's East Coast Pagers. He's a great guy, very honest and helpful, and has been a member and database admin here for many years! Don't take a change with less reputable sellers who may not even be authorized unication dealers.

East Coast Pagers - Your Emergency Alerting Specialists

East Coast Pagers is a Unication Pager Dealer, a Swissphone Pager Dealer, and an Apollo Pager Dealer specializing in the Unication G1, Unication G2, Unication G3, Unication G4, and Unication G5 Pagers. We also specialize in Swissphone sQuad Pagers.

www.eastcoastpagers.com

 

[GTR8000]

Yes, @w2lie is the man when it comes to Unication. Spend your money wisely and go with a guy who has a solid reputation and a lot of happy customers.

 

[APX8000]

Phil and Ray are both solid. I had to plug Ray as well since he's been solid. Please stay away from those that are NOT dealers and who prematurely blurt out crap on Facebook groups without knowledge of how things actually work.

 

[GTR8000]

Please stay away from those that are NOT dealers and who prematurely blurt out crap on Facebook groups without knowledge of how things actually work.

This can't be stressed enough. If anyone in the county is reading this and considering buying a Unication pager, please only deal with an authorized dealer so that you are the original owner of record, and won't have any warranty issues. The person in the eastern part of the county who is chomping at the bit to sell you a pager is not an authorized dealer; this was confirmed by Unication today.

Also, pay attention to the info the fire coordinator's office put out regarding the paging talkgroup.