How to decode P25T Phase I/II NACs?

freeonfreak · Jul 17, 2015

Just purchased a BCD396XT and I cannot find any info on how to decode/scan a P25T Phase I/II NAC.

I've already downloaded Pro96Com but it doesn't provide the NAC.

I may have to return it if I can't get the P25T Phase I/II System NAC from this device.

N8IAA · Jul 17, 2015

Just curious, why do you need the NAC?
Larry

freeonfreak · Jul 17, 2015

I program radios for my customers on complex and large P25T systems. Because our radios can automatically register on P25T Phase I/II systems, sometimes they want me to program the radio to manually register to a single site and not "roam" to other sites. So this process requires manual entry of the System NAC.

KevinC · Jul 17, 2015

fmedelli said:
I program radios for my customers on complex and large P25T systems. Because our radios can automatically register on P25T Phase I/II systems, sometimes they want me to program the radio to manually register to a single site and not "roam" to other sites. So this process requires manual entry of the System NAC.

I would HIGHLY suggest you get with the system owner and not rely on gathering information from a scanner.

But the 396XT will show the channels NAC, just press "Hold", enter the frequency and press "Hold" again and wait for them to talk.

freeonfreak · Jul 17, 2015

Thanks!

UPMan · Jul 17, 2015

NAC is used for conventional P25 channels, not P25 Phase I/II systems. The scanner will scan any site that is programmed and enabled.

tampabaynews · Jul 17, 2015

NAC is certainly used in P25 Trunking, it just not very important for monitoring the trunked system with a scanner. But it's required for radio units. I would also suggest getting with the system admin and use caution.

Here is my method, program one of the system voice frequencies as a conventional channel. Make sure the channel is set as digital only and also NAC search. You should see the NAC when a transmission lands on that frequency.

However as far as I know, this method will only work with Phase I transmissions. The scanner may not know how to handle a Phase II transmission when you program the frequency in conventional mode.

KevinC · Jul 17, 2015

UPMan said:
NAC is used for conventional P25 channels, not P25 Phase I/II systems. The scanner will scan any site that is programmed and enabled.

Not going to get nit-picky, but P25 trunked systems do use/have a NAC. It doesn't come into play for scanners, but I suspect the OP is programming "real" radios (more than likely Harris).

Voyager · Jul 17, 2015

tampabaynews said:
NAC is certainly used in P25 Trunking

But the scanner in question does NOT use the NAC for P25 trunking. (no matter how much the system uses it)

smithken · Jul 17, 2015

The 396XT doesn't work with phase II.

oracavon · Jul 17, 2015

Voyager said:
But the scanner in question does NOT use the NAC for P25 trunking. (no matter how much the system uses it)

Also, the scanner in question doesn't handle P25 Phase 2. Just sayin'...

Edit: I see that smithken just beat me to it. I need to type faster.

Voyager · Jul 17, 2015

oracavon said:
Also, the scanner in question doesn't handle P25 Phase 2. Just sayin'...

Edit: I see that smithken just beat me to it. I need to type faster.

Actually, it will decode a Phase II control channel just fine since they are the same. It just won't decode the Phase II audio. A Phase II system operating in Phase I compatibility mode will work fine on a 396XT.

tampabaynews · Jul 17, 2015

Voyager said:
But the scanner in question does NOT use the NAC for P25 trunking. (no matter how much the system uses it)

Precisely. Which is why immediately after that I said...

tampabaynews said:
...it just not very important for monitoring the trunked system with a scanner. But it's required for radio units.

LOL

However, as I also said... the NAC can still be decoded using that scanner when the a trunked frequency is programmed conventionally and receives a Phase I transmission.

This is what the OP was asking and it can be done.

oracavon · Jul 17, 2015

Voyager said:
Actually, it will decode a Phase II control channel just fine since they are the same. It just won't decode the Phase II audio. A Phase II system operating in Phase I compatibility mode will work fine on a 396XT.

Well, yeah, a phase 2 system in phase 1 mode is transmitting phase 1. I was referring to phase 2 transmissions. The question is whether that scanner will decode the NAC of a phase 2 transmission. tampabaynews's post seems to indicate that it doesn't.

UPMan · Jul 17, 2015

Yes, I was speaking in the context of the scanner.

freeonfreak · Jul 18, 2015

Yes, Harris Full-Spectrum radios. Fact, per TIA the CC is always running Phase I. The WC can run in Phase II but when a Unit registers on that site with a Phase I radio, it'll downgrade the entire (Moto) site to phase I. However, a Harris System has Enhanced Dual-Dynamic Mode which only downgrades that WC at one site and let's the rest of the sites be Phase II even on that same TG.

Now back to my reason for needing the NAC, I've recently ran into a system that the CC and WC have two different NACs. Weird, yes. And I'm trying debug my radios so I can best program them for the customer(s).

KevinC · Jul 18, 2015

fmedelli said:
Yes, Harris Full-Spectrum radios.

Now back to my reason for needing the NAC, I've recently ran into a system that the CC and WC have two different NACs. Weird, yes. And I'm trying debug my radios so I can best program them for the customer(s).

That's typical of Harris systems.

And getting with the system owner is still the best route...in my opinion. :wink:

How to decode P25T Phase I/II NACs?

freeonfreak

Member

N8IAA

Member

freeonfreak

Member

KevinC

Junior Radio Guru

freeonfreak

Member

UPMan

In Memoriam

tampabaynews

Keeping your PIO busy

KevinC

Junior Radio Guru

Voyager

Member

smithken

Member

oracavon

Member

Voyager

Member

tampabaynews

Keeping your PIO busy

oracavon

Member

UPMan

In Memoriam

freeonfreak

Member

KevinC

Junior Radio Guru

Similar threads