so...................... I guess we know Fleetnet Zone 1 digital talkgroups trunked are 2D0 and niagara regional police conventional digitals , encrypted, but 2d4 .
There's a couple of things that need to be cleared up here.
(1) Conventional NAC has a different purpose than trunked NAC. Conventional NAC like Saint was mentioning for Niagara Regional Police is the digital equivalent of CTCSS/DCS on an analog conventional channel - it is transmitted along with the audio, to identify the user in a general sense. It's possible to have different "channels" on the same frequency if you use different NACs, same as you can have different channels on the same analog frequency if one user (group) is using, say, CTCSS 107.3, and the other is using CTCSS 151.4.
(1a) NAC 293 is the default NAC in many/most radios' P25 channel programming - Motorola definitely, others I don't know. Some say "NAC 293 is the equivalent of analog CSQ" but that's not quite the truth. If you see NAC 293, the person programming the channels didn't bother to move away from the default settings.
(2) Trunked NAC exists on the
frequency for the trunk system, not the
talkgroup. NACs do not change on a trunk system from talkgroup to talkgroup. Every frequency at a given site is going to have the same NAC, regardless of what talkgroup it's currently carrying.
The system ID (four-digit hexadecimal identifier) for Fleetnet zone 1 is
782D. As mentioned previously, in systems like Fleetnet (Smartzone and Smartzone Omnilink systems), the NAC of a site frequency is the last two digits of the system ID - in this case,
2D, and a number representing the Connect Tone. There are eight different Connect Tones, as described here:
Motorola - The RadioReference Wiki - so a site on Fleetnet Z1 that has a Connect Tone of 97.3 will show a NAC of
2D4.
Connect Tone and trunked site NAC have very little meaning to the average scanner user. The scanners don't need them in order to track the system, and when you are using the scanner in trunking mode, they don't even show up. Only if you stop on a trunk site voice frequency in conventional mode will you see a NAC displayed.
The purpose of a NAC in a trunk system is so that the system (and subscriber radios) can tell if a given frequency belongs to one site or another. As I was trying to explain earlier in the thread, systems re-use frequencies across their network, so 138.945 might be on site 21, but also on site 52. Those two sites would have different connect tones, so that a radio would know to disregard any traffic on 138.945 (if it could hear it) unless its NAC matched the proper values for the site the radio is affiliated (logged on) to.
As I said, most scanner users will have no use for the trunked NAC. If you're trying to identify talkgroups, they're already in the database.. if you have talkgroups that aren't in the DB and you want to know who is using them, one of the best ways is to run a trunking analyzer (Unitrunker or Trunk88, or the HomePatrol scanner in Extreme mode) and see which radio IDs are transmitting on that talkgroup. Generally you will be able to spot a pattern between known talkgroups (and radio users) and the unknowns. Example: if talkgroup 32768 is known to be a police traffic unit channel and radio 40991 is talking on it, and you have unidentified talkgroup 2880 which also has radio 40991 talking on it, you can be pretty certain it's a police talkgroup, and mildly certain it might have something to do with traffic (but not always).