NXDN Control channel Only

ofd8001

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#1
Can NXDN be programmed as control channel only as like some other systems, or is it where all frequencies are needed and then do they have to be in a channel order?

Then another question may come up, what if a frequency is not programmed in, as long as at isn't a possible control channel? Also, what if some extraneous frequency is added?
 

gh6406

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#2
Can NXDN be programmed as control channel only as like some other systems, or is it where all frequencies are needed and then do they have to be in a channel order?

Then another question may come up, what if a frequency is not programmed in, as long as at isn't a possible control channel? Also, what if some extraneous frequency is added?
I do believe that if it is a Trunked System, then you need all frequencies and the correct LCN order. As far as extra frequencies in the list, I do not know if that will affect scanning the system or not.
 
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#3
I’ve been monitoring a multiple site system. Several of the sites have a frequency or two that the 436 hasn’t been able to determine the LCN. . In my experience, having an extraneous frequency does not appear to impact monitoring the system.
 

werinshades

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#4
Can NXDN be programmed as control channel only as like some other systems, or is it where all frequencies are needed and then do they have to be in a channel order?

Then another question may come up, what if a frequency is not programmed in, as long as at isn't a possible control channel? Also, what if some extraneous frequency is added?
No it can't...already tried. If a frequency is not programmed, you will probably miss transmissions. Frequencies don't have to be "in order", but have to be assigned a "channel number" in the LCN column when programming NXDN trunk systems.

Both ProScan and ARC currently support NXDN programming. It's sounding like Sentinel next week with a firmware "tweak" upgrade.
 

cg

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#8
Pretty sure that NXDN does not transmit a band plan. NXDN transmits channel numbers to tune to. That matches up with frequencies that are already programmed into the radios. There are three systems that I monitor. Two use random numbers that cannot be put into a band plan. The other uses frequencies that can be predicted by math

Examples of the two random and the one by math.
System A - Ch 220, 230, 240, 250
System B - Ch 68, 69, 70, 71, 72
System C - Ch 113, 167, 699, 711

chris
 

kd7kdc

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#9
There seems to be two flavors of NXDN.

1. The EXPLICIT ((Channel plan based on a starting frequency (Base) and the (Step) ie 6.25 12.5 etc))
like P25/Moto Type 1 and 2.

2. The CUSTOM Channel plan where the radio shop system admin designates channel numbers.
 

cg

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#12
I use DSDPlus to find LCNs. I then use a scanner and the FCC database to match the active LCNs with frequencies. If you know all your frequencies, perhaps from an old system that is being upgraded, it is fairly easy to match them up.

chris
 

werinshades

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#13
Thanks for the info!

So if there has to be a LCN, how would one determine that if it is not listed in the RR database?
If you have (or seem to have) all the frequencies via a Conventional search, run LCN Finder and this should get you the channel numbers. I know some listings in the database show the frequency and the number 0 after it, which will not work. If you're lucky enough to have the frequencies, program them in the site, set Search for RAN and leave channel number blank. This should get you a majority if not all the channel numbers.
 

troymail

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#14
Edit: I think your original question - can you have NXDN "control channel only" has been answered.... I suspect that right now (and maybe always) the answer is no. However, we have seen some indications of systems which use one or more forms of a "standard" and perhaps that could be used in some type of improvement (or at least things that can be "tried" in a more automated fashion) in the future.

FWIW - I've been working with some folks on both NXDN and DMR "systems" - some that are listed in the RRDB and some that are not.

We've determined that some data is old and/or was never really accurate. In the more recent cases, two county "systems" were listed as CON+ but are really just DMR. A user determined some of the TGs and attached them to the "system" that was listed but then could not hear anything -- of course, it was because the system was imported as CON+ when in fact it is essentially conventional.

In another case, the NXDN "system" is in fact a system but was old and outdated -- apparently there was a "trial period" using a single set/set of frequencies which eventually was replaced with a multi-site NXDN system but never changed/updated in the RRDB (it is now).

We're working another system now - a system that even has TGIDs listed - and finding that the system/site frequency data is just wrong and even some of the TGIDs are listed incorrectly (fire is actually police, etc.). This one is particularly challenging as we've determined that the frequencies is use are spread over multiple licenses and multiple licensees (some are county, some appear a company) in that county. What a mess.

It just takes time..... lots of it.
 
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ofd8001

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#15
Thanks for the information.

This is my first foray into programming a NXDN system (https://www.radioreference.com/apps/db/?sid=7031). I've downloaded it a couple of times with no success on reception.

So I'm trying some different things and these questions come up. The DB Admin says the RR stuff is accurate, but it is kind of weird (I think) a 14 frequency TRS with just 14 talkgroups.
 

mtindor

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#16
Thanks for the information.

This is my first foray into programming a NXDN system (https://www.radioreference.com/apps/db/?sid=7031). I've downloaded it a couple of times with no success on reception.

So I'm trying some different things and these questions come up. The DB Admin says the RR stuff is accurate, but it is kind of weird (I think) a 14 frequency TRS with just 14 talkgroups.
If you are using a Whistler scanner that supports NXDN, you should hear some traffic (assuming you have the talkgroups added and/or have a group wildcard set).

If you are using a Uniden scanner, you should not expect to hear anything on that system since the database lists all of the LCNs as 0 -- and the LCNs must be known and properly programmed into the scanner for the Uniden to trunk properly.

It is odd to imagine 14 trunked repeaters in use for a school system, but not really out of line. The more important thing is that if you imported that site into your BCD436/536, it isn't going to trunk because all of the LCNs are listed as "0". Although those 14 frequencies are licensed to the school system with NXDN emissions, it is very possible that not all of them are active in the trunked system.

You really need to monitor that system during busy school days. And if you have imported that system into a Uniden, the only way you will hear anything is if you run LCN Finder and determine all of the LCNs in use on the system. Without the LCNs being known, you are dead in the water.

Fortunately, LCN Finder works great. So give that a try. But if you are listening on a weekend there will likely be significantly less traffic, which will make it much more difficult for LCN Finder to find LCNs. In order to find LCNs, there must be plenty of traffic on the system.

Mike
 

werinshades

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#17
If you are using a Whistler scanner that supports NXDN, you should hear some traffic (assuming you have the talkgroups added and/or have a group wildcard set).

If you are using a Uniden scanner, you should not expect to hear anything on that system since the database lists all of the LCNs as 0 -- and the LCNs must be known and properly programmed into the scanner for the Uniden to trunk properly.

It is odd to imagine 14 trunked repeaters in use for a school system, but not really out of line. The more important thing is that if you imported that site into your BCD436/536, it isn't going to trunk because all of the LCNs are listed as "0". Although those 14 frequencies are licensed to the school system with NXDN emissions, it is very possible that not all of them are active in the trunked system.

You really need to monitor that system during busy school days. And if you have imported that system into a Uniden, the only way you will hear anything is if you run LCN Finder and determine all of the LCNs in use on the system. Without the LCNs being known, you are dead in the water.

Fortunately, LCN Finder works great. So give that a try. But if you are listening on a weekend there will likely be significantly less traffic, which will make it much more difficult for LCN Finder to find LCNs. In order to find LCNs, there must be plenty of traffic on the system.

Mike
Just to add:

Run your scanner in Conventional Search during the week. When it comes near the frequency, press the channel indicator and walk it to the frequencies and hold it. Wait for activity. If you see a RAN write it down. See if all frequencies have the same RAN, if not it might be different systems.

Second think I see is it's labeled as a 9600 NXDN system. There is some postings on here regarding monitoring these systems by switching it to FM.

Once you are confident you have the proper frequencies (Not all may be used, but are licensed) , then run LCN finder and get the "channel numbers". Submit your findings to the database administrator as he/she might not be familiar with NXDN programming necessities yet.
 

troymail

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#18
Thanks for the information.

This is my first foray into programming a NXDN system (https://www.radioreference.com/apps/db/?sid=7031). I've downloaded it a couple of times with no success on reception.

So I'm trying some different things and these questions come up. The DB Admin says the RR stuff is accurate, but it is kind of weird (I think) a 14 frequency TRS with just 14 talkgroups.
That is a pretty odd looking listing - if for nothing else the short names assigned to the talkgroups (really helpful, eh?). The two referenced licenses only show 6 and 1 (7 total) repeater frequencies respectively. On the other hand, Jefferson County Public Schools appear to have 15 separate "active" licenses... so who really knows.

I'd check each of the listed frequencies to determine which if any have a steady control channel signal present. Then, perhaps program the group of frequencies with only 1 that has a control channel present (remove/lockout any others that sound like a CC for now), and then run LCN finder against that setup (on a school day of course). Chances are, the LCN finder might never finish but again, who knows (I don't know if LCN finder is smart enough to know it has all LCNs when there are fewer than the number of programmed frequencies - or what it does if you are missing some).

If you find more than one control channel frequency, I would repeat the process replacing the first CC frequency with a different one and try LCN finder again....
 
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ofd8001

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#19
Thanks to all who replied - you've given me thoughts on what to do next.

The talkgroup names are for bus compounds/depots, so that does make sense. Some of the licensed frequencies are holdovers from years gone by and others are for individual schools.
 

jodyobrien

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#20
Confirming we are talking about programming NXDN, right? If a different system type, please start a new thread and I'll help you there.
The starting steps are:

MENU
MANAGE FAVORITES
NEW FAVORITES LIST (or select an existing one to use)
(set the options - rename etc if you want)

Select REVIEW/EDIT SYSTEM
NEW SYSTEM
Select the system type you want: NXDN TRUNK for trunking systems, NXDN OneFrequency for single frequency trunks, or Conventional for conventional channels.

For conventional only, create a new Department, then within that new channel, then program teh frequency for that channel. Set the audio type as DIGITAL ONLY and set the RAN if known. Repeat for any additional channels.

For NXDN OneFrequency, select EDIT SITE, add a new site, then select SET FREQUENCIES and enter the frequency. After that, set ID SCAN to ON or select EDIT DEPARTMENT, NEW DEPARTMENT, NEW CHANNEL, then enter the Talkgroups you want to scan.

For NXDN TRUNK:
select EDIT SITE, add a new site, then select SET FREQUENCIES and enter the frequencies for each LCN. If you don't know the LCN, just hit ENTER for now on that field. Repeat until all the site frequencies are entered. After that, set ID SCAN to ON or select EDIT DEPARTMENT, NEW DEPARTMENT, NEW CHANNEL, then enter the Talkgroups you want to scan.

If you don't know the LCN, use LCN FINDER to find them as follows: (you will need to remember the System name you set above)
In the menu, select ANALYZE then LCN FINDER. Hit ENTER and scroll to the system and select it, then select the SITE and LCN Finder will start. when it's done, it will let you know and you can set all the found LCNs.

Now one word of caution here: IF there are frequencies that are not used, it will never find the LCN for them. But, it will give you the option of saving what it has found when you exit the LCN finder using FUNC-SYSTEM. It will ask if you want to save found LCNs. Select YES.

The above should get you running.
 
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