DSD+ P25 NAC question

Status
Not open for further replies.

Airdorn

Member
Premium Subscriber
Joined
Mar 9, 2008
Messages
429
Hi.

I'm pretty new to DSD+.

When decoding a P25 system, I get a constant updating stream of information, including a value called 'NAC'. I noticed that the NAC appears to be very similar to the System ID.

For example, one P25 system I monitor has a system ID of BEE00-14C.

DSD+ shows the following:

Sync:p25p1 NAC: 140 TSDU

My question is, can I actually reliably glean the system ID from this DSD+ information? Are NAC and the system ID related in that way?

Here's another example:

Unitrunker (and RR database) indicate Entergy as BEE00-64F.

DSD+ NAC is 640


Thanks!
 
Last edited:

dave3825

Member
Premium Subscriber
Joined
Feb 17, 2003
Messages
2,654
Location
New York
About the value "NAC" in the data stream,


Conventional P25 systems don't support CTCSS tone or DCS code for access. Instead they use what is called a Network Access Code, or NAC. The NAC is a feature similar to CTCSS or DCS for analog radios. That is, radios can be programmed to only break squelch when receiving the correct NAC.


I follow a few systems and sometimes the nac is similar to the sys id.

Your system BEE00 14C, with a nac of 140, should be United States Department of Defense . Are you in or close to any of these states?
CA WA VA FL GA SC TX IN NV PA IL UT AZ CT NJ RI LA TN WV AL ME DC

If it is indeed the mentioned system above, you can actually edit your DSDPlus.networks file and add the following line to have it display the system name with in dsdplus

P25, BEE00.14C, "Department of Defense (14C)"

or

P25, BEE00.14C, "DOD (14C)"

or

P25, BEE00.14C, "whatever you want to call it."
 

Airdorn

Member
Premium Subscriber
Joined
Mar 9, 2008
Messages
429
About the value "NAC" in the data stream,


Conventional P25 systems don't support CTCSS tone or DCS code for access. Instead they use what is called a Network Access Code, or NAC. The NAC is a feature similar to CTCSS or DCS for analog radios. That is, radios can be programmed to only break squelch when receiving the correct NAC.


I follow a few systems and sometimes the nac is similar to the sys id.

Your system BEE00 14C, with a nac of 140, should be United States Department of Defense . Are you in or close to any of these states?
CA WA VA FL GA SC TX IN NV PA IL UT AZ CT NJ RI LA TN WV AL ME DC

If it is indeed the mentioned system above, you can actually edit your DSDPlus.networks file and add the following line to have it display the system name with in dsdplus

P25, BEE00.14C, "Department of Defense (14C)"

or

P25, BEE00.14C, "DOD (14C)"

or

P25, BEE00.14C, "whatever you want to call it."
Dave, you are correct. It's the US Dept. of Defense site. I'm in TN and the site is the Naval Support Activity in Millington. I was using that as an example.

I was just wondering if the DSD+ NAC of 140 was intimately connected to that system's SysID of 14C. Since DSD+ seems to start decoding stuff a lot faster than other programs, especially on weaker signals, I was hoping to glean the site ID from that DSD+ stream of info. :)


But it looks like there is not a correlation there, necessarily.

Thanks for your info, especially the part about the DSD.networks file!
 

dave3825

Member
Premium Subscriber
Joined
Feb 17, 2003
Messages
2,654
Location
New York
When you first start dsd, it should show you the current site, and the sight neighbors.

Like in the pic below. If you see the site number, you can also edit the DSDPlus.sites file and label them like in the networks file.

I edited mine to reflect the system name, (Onevoice NY) but have not done the sites yet. The onevoice system is a multi site system spanning across a few states.

You can sometimes match the site by the control channel freq. But sometimes the cc is used on more than one site.


As seen on this site on the dod system, this one reflects nac 140. I looked at the TN ones and it says n/a so I would guess nobody ever submitted the nac info.

https://www.radioreference.com/apps/db/?siteId=15423





.
 

Attachments

D

DaveNF2G

Guest
I edited mine to reflect the system name, (Onevoice NY) but have not done the sites yet. The onevoice system is a multi site system spanning across a few states.
Slightly OT from the thread, but if you want a DSDPlus file for OneVoice that has the known sites I can send you mine. I also have an extensive .networks file that you might be able to integrate into your own listings.

Send me a PM if you're interested.
 

dave3825

Member
Premium Subscriber
Joined
Feb 17, 2003
Messages
2,654
Location
New York
Slightly OT from the thread, but if you want a DSDPlus file for OneVoice that has the known sites I can send you mine. I also have an extensive .networks file that you might be able to integrate into your own listings.

Send me a PM if you're interested.


Pm sent. Thank you Dave
 
Status
Not open for further replies.
Top