NXDN Update Now Available!

[troymail]

Hi Troy, thanks for the further updates. Can you or have you followed a trunked system and then stopped and hold on a specific talkgroup? In doing so, are you able to follow further conversations?
Thanks, Scott

Yes

This came up later and so I'm back to qualify the Yes response:

BTW - I forgot to mention earlier that for a couple of systems in my area, there are user sets where the base radio uses 1 talkgroup and each of the mobile units responds on completely different talkgroups (i.e. base + 10 mobile users = 11 different talkgroups)... and in these situations, two things you do not want to do are (a) HOLD on any talkgroup and (b) have delay enabled. The latter (no delay) becomes a huge problem on busy systems and/or when it isn't the only system you are scanning.

 

[werinshades]

I've been experimenting with a large NXDN system with 25 frequencies. The difficulty here is the numerous "possible" frequencies the Talk group will go to. I've done many tweaks..control channel, no control channel...NXDN-C/NXDN-D, programming each site per RAN, and have come to the conclusion that my 1 site, set RAN to ANY and NXDN 4800/NXDN-C programming method appears to work the best. I've reached out on the Illinois forums to see if anyone monitoring the system has any better solutions without a response. Probably a lack of NXDN capability scanners out there, and a lack of interest in business monitoring is the reasons I suspect. The system administrator "probably" assigns each talk group a "primary" frequency chain based upon their location and RAN. For larger systems, this would be very difficult to pinpoint if you want to monitor more than 1 user on the system. That has been my findings with a TRX-2.

 

[troymail]

I've been experimenting with a large NXDN system with 25 frequencies. The difficulty here is the numerous "possible" frequencies the Talk group will go to. I've done many tweaks..control channel, no control channel...NXDN-C/NXDN-D, programming each site per RAN, and have come to the conclusion that my 1 site, set RAN to ANY and NXDN 4800/NXDN-C programming method appears to work the best. I've reached out on the Illinois forums to see if anyone monitoring the system has any better solutions without a response. Probably a lack of NXDN capability scanners out there, and a lack of interest in business monitoring is the reasons I suspect. The system administrator "probably" assigns each talk group a "primary" frequency chain based upon their location and RAN. For larger systems, this would be very difficult to pinpoint if you want to monitor more than 1 user on the system. That has been my findings with a TRX-2.

I've played with NXDN trunked systems where the activity level is a bit slow and talkgroups have a "home" frequency assigned and the talkgroup stays on that frequency unless it is already in use, at least one fairly busy multi-site public safety system where the controlled constantly assigns a talkgroup a different frequency, systems where the only frequency that seems to be used is the control channel (voice pops up on the control channel frequency itself, and others where the control channel frequency is used as a "last resort, overflow" voice channel.

The larger the number of frequencies that a site has (and are programmed), the more likely you're going to miss traffic - even when holding on a talkgroup.

And - if you don't have all of the frequencies associated with a site of a given system, there's a good chance you'll miss traffic.

To summarize the last two points - it's very important that you have all/only the frequencies associates with a given site programmed for that site.

From my experience, from what I've seen, nearly every NXDN system seems to be "just a little bit different"... very different from older Motorola and P25 public safety type systems.

 

[werinshades]

I've played with NXDN trunked systems where the activity level is a bit slow and talkgroups have a "home" frequency assigned and the talkgroup stays on that frequency unless it is already in use, at least one fairly busy multi-site public safety system where the controlled constantly assigns a talkgroup a different frequency, systems where the only frequency that seems to be used is the control channel (voice pops up on the control channel frequency itself, and others where the control channel frequency is used as a "last resort, overflow" voice channel.

The larger the number of frequencies that a site has (and are programmed), the more likely you're going to miss traffic - even when holding on a talkgroup.

And - if you don't have all of the frequencies associated with a site of a given system, there's a good chance you'll miss traffic.

To summarize the last two points - it's very important that you have all/only the frequencies associates with a given site programmed for that site.

From my experience, from what I've seen, nearly every NXDN system seems to be "just a little bit different"... very different from older Motorola and P25 public safety type systems.

The issue I've seen in my scenario is the talk groups switch between different RAN's. For example, RAN-6 is based on top of the Sears Tower and has the most frequencies assigned. I've found and continue to search for additional frequencies in this system and have yet to find anything new. While holding on any specific talk group, I'm hearing both sides of the conversations...this is using my 1 site/all frequencies programmed in. I don't quite understand the reasoning of putting in 6 different sites, each with their own frequencies and how that would speed up scanning or guarantee to follow conversations. I've seen conversations start on a RAN-6 frequency, then go to a RAN-16 frequency, and end on a RAN-24 frequency. In my programming method, all frequencies in 1 site and the scanner should follow the talk group by following the frequencies the same?

 

[troymail]

I don't quite understand the reasoning of putting in 6 different sites, each with their own frequencies and how that would speed up scanning or guarantee to follow conversations.

Typically, like any multi-site trunking system, you'd normally program each of the site frequencies as "a site". For example, if there are six sites and each site has, again, for example, 5 frequencies, programming should be a system that has 6 sites and the frequency tables for each would contain their respective 5 frequencies.

And, typically, you'd only want to have the closest site enabled (i.e. scanning 1 site with 5 frequencies). That doesn't mean you can't choose to scan more than one site but as I've always told folks -- in my example above - I would have 6 copies of the system with only one site enabled in each copy (with all of the talkgroups including a wildcard assigned to 6 different scanlists corresponding to the site frequencies for that site). This way, I can toggle on and off whatever site I want to listen to at any given time. If I want to, I might listen to, for example, the site closest tom me and maybe 1 or 2 sites that are "near" if the signal(s) are strong enough.

I understand you are still trying to sort through the frequencies and RAN values. As I mentioned previously, every system to be seems to be different but typically I've seen common RAN values for the frequencies associated with each site (that is - your situation sound different perhaps). Aside from the site frequency analysis, when programming, I'd leave RAN set to any.

I know you've spent quite a bit of time working on this system and it sounds like a huge challenge but it sounds like there are still things not understood yet so keep plugging away....

BTW - I forgot to mention earlier that for a couple of systems in my area, there are user sets where the base radio uses 1 talkgroup and each of the mobile units responds on completely different talkgroups... and in these situations, two things you do not want to do are (a) HOLD on any talkgroup and (b) have delay enabled. The latter (no delay) becomes a huge problem on busy systems and/or when it isn't the only system you are scanning.

Many of these issues - coupled with my almost complete lack of interest in the activity on these systems (with exception of the trunked NXDN public safety system I play with), I've just "moved on" / back to more interesting things....

 

[werinshades]

Typically, like any multi-site trunking system, you'd normally program each of the site frequencies as "a site". For example, if there are six sites and each site has, again, for example, 5 frequencies, programming should be a system that has 6 sites and the frequency tables for each would contain their respective 5 frequencies.

And, typically, you'd only want to have the closest site enabled (i.e. scanning 1 site with 5 frequencies). That doesn't mean you can't choose to scan more than one site but as I've always told folks -- in my example above - I would have 6 copies of the system with only one site enabled in each copy (with all of the talkgroups including a wildcard assigned to 6 different scanlists corresponding to the site frequencies for that site). This way, I can toggle on and off whatever site I want to listen to at any given time. If I want to, I might listen to, for example, the site closest tom me and maybe 1 or 2 sites that are "near" if the signal(s) are strong enough.

I understand you are still trying to sort through the frequencies and RAN values. As I mentioned previously, every system to be seems to be different but typically I've seen common RAN values for the frequencies associated with each site (that is - your situation sound different perhaps). Aside from the site frequency analysis, when programming, I'd leave RAN set to any.

I know you've spent quite a bit of time working on this system and it sounds like a huge challenge but it sounds like there are still things not understood yet so keep plugging away....

BTW - I forgot to mention earlier that for a couple of systems in my area, there are user sets where the base radio uses 1 talkgroup and each of the mobile units responds on completely different talkgroups... and in these situations, two things you do not want to do are (a) HOLD on any talkgroup and (b) have delay enabled. The latter (no delay) becomes a huge problem on busy systems and/or when it isn't the only system you are scanning.

Many of these issues - coupled with my almost complete lack of interest in the activity on these systems (with exception of the trunked NXDN public safety system I play with), I've just "moved on" / back to more interesting things....

I know we've gone around and around on this. As you probably figured out, I've programmed many different types of systems, including Starcom 21 which is a P25 simulcast system. In these "normal" scenarios, you are correct..program in the strongest and closest site and a way we go.

In the NXDN system I've been working on, I've done all your suggestions. Here's an anomaly..I live by Midway Airport and told my story of trying to find the shuttle buses, which I found. 2 different companies..one for rental center transports, the other handles employees/economy parking lots...to and from the airport. On your and Eric's suggestion, I did just that...eliminated all but one site..24 which works off Midway Airport. The only thing I heard was the Rental Shuttle, not the other. I then added RAN-6 frequencies and tried again...I heard the employee shuttle company and "some" of the other radio traffic, but still not the normal. I then added the other 4 sites, and the radio was squawking away.

My next "experiment" was to hold on the Employee Shuttle Talk group to see if I could pick up the radio traffic. I'll also had I had someone "on the inside" who was riding the bus at the same time in close proximity to the radio, and was listening as I was. All traffic was heard...and I was using my 1 site/all frequency method.

As with all radio systems, their are many variations out there. Since we've never seen a "how-to" program NXDN systems, I'm just experimenting to see what works best. Could these frequencies be "simulcasting" on different RAN's? I suspect it could be, but since I don't have a 2nd NXDN scanner to check, I won't go out and say it's a definitive yes yet. Would it be better to only program RAN-6 & 24 frequencies? I guess I could try that next. Unfortunately, not many out here close by are experimenting so it's hard to say. As always, I appreciate any/all suggestions.

 

[troymail]

More things making your research a challenge....

I'm looking at the Sears Tower site -- which RRDB lists only 471.3125 as a frequency....

The license indicates that as the only repeater frequency (but that doesn't mean other frequencies site that site aren't listed under a different license...). Anyway, this license does indicate analog and NXDN emission types.

However, there is another licencee for 471.3125 that is northwest of Chicago. It has two repeater frequencies and lists analog, NXDN and DMR emission types.

Are these licensees related?

Clearly you've go your hands full...

I may have said this previously and/or you may have tried it but if a site is very active, I think I'd probably go sit pretty close to the tower/transmitter and run sweeper searches and/or antenna-less searches and build a list of information that way.

 

[EricCottrell]

Hello,

On a multiple-site system, the same talkgroup can appear on multiple sites. Programming everything as one site will result in the scanner using the first frequency it finds transmitting the talkgroup regardless of the site. You may have not found all the frequencies yet.

The RAN value on a NXDN Type-C trunked system is the site number modulus 64. So it is highly likely that the same RAN numbers are the same site. It is not 100% since Site 5 would share the same RAN value as 69, 133, 197, etc. The system being discussed is big enough to have over 64 sites.

NXDN 4800 systems can be tricky because of the very narrow bandwidth. There is a local site that is hard to find during a search because it is on a 6.25 KHz splinter channel. Other systems use a 12.5 KHz channel for two NXDN channels, with one 3.125 KHz below the assigned frequency and the other 3.125 above the assigned frequency. The scanner could possibly pickup either channel if it was active but not if both are active. You really need to resolve frequencies to within 3.125 KHz.

Taxi companies tend to have radio setups that prevent the cabs from talking to each other. I have seen the base transmit on a broadcast talkgroup and each cab is on it's own talkgroup.

I have not done much searching with my TRX-2. I find it easier to use use a SDR or Receiver with a spectrum display. The waterfall helps finding stuff like Cap+ and NXDN Type D systems that send out short bursts.

I also tend to use a program to monitor the control channel to see what channel numbers are assigned to the voice calls. This gives me an idea of how many channels are in use and if I need to search for more. It might be possible to find frequencies if a few frequency to channel number relationships are known.

73 Eric

 

[werinshades]

More things making your research a challenge....

I'm looking at the Sears Tower site -- which RRDB lists only 471.3125 as a frequency....

The license indicates that as the only repeater frequency (but that doesn't mean other frequencies site that site aren't listed under a different license...). Anyway, this license does indicate analog and NXDN emission types.

However, there is another licencee for 471.3125 that is northwest of Chicago. It has two repeater frequencies and lists analog, NXDN and DMR emission types.

Are these licensees related?

Clearly you've go your hands full...

I may have said this previously and/or you may have tried it but if a site is very active, I think I'd probably go sit pretty close to the tower/transmitter and run sweeper searches and/or antenna-less searches and build a list of information that way.

Yes...alot of the submitted information is not correct. I'm holding off submitting the information to the database until I can get some confirmation. I have many talk groups, some confirmed, others a pretty good idea. I have alot of index cards with all kinds of useless (to the average bear) information. Obviously I like a good challenge...but thanks for the tips.

 

[werinshades]

Hello,

On a multiple-site system, the same talkgroup can appear on multiple sites. Programming everything as one site will result in the scanner using the first frequency it finds transmitting the talkgroup regardless of the site. You may have not found all the frequencies yet.

The RAN value on a NXDN Type-C trunked system is the site number modulus 64. So it is highly likely that the same RAN numbers are the same site. It is not 100% since Site 5 would share the same RAN value as 69, 133, 197, etc. The system being discussed is big enough to have over 64 sites.

NXDN 4800 systems can be tricky because of the very narrow bandwidth. There is a local site that is hard to find during a search because it is on a 6.25 KHz splinter channel. Other systems use a 12.5 KHz channel for two NXDN channels, with one 3.125 KHz below the assigned frequency and the other 3.125 above the assigned frequency. The scanner could possibly pickup either channel if it was active but not if both are active. You really need to resolve frequencies to within 3.125 KHz.

Taxi companies tend to have radio setups that prevent the cabs from talking to each other. I have seen the base transmit on a broadcast talkgroup and each cab is on it's own talkgroup.

I have not done much searching with my TRX-2. I find it easier to use use a SDR or Receiver with a spectrum display. The waterfall helps finding stuff like Cap+ and NXDN Type D systems that send out short bursts.

I also tend to use a program to monitor the control channel to see what channel numbers are assigned to the voice calls. This gives me an idea of how many channels are in use and if I need to search for more. It might be possible to find frequencies if a few frequency to channel number relationships are known.

73 Eric

As always Eric, I appreciate your input as well. I believe you or Troy called the Midway site a "splinter site" since it doesn't have an active control channel. I'm trying different combinations, and if I can park by buttocks in the chair during the day, that seems to be the best time to experiment.

As far as the frequencies go, I have checked licenses versus searches. I've parked on licensed frequencies to evaluate if I missed one or two. So far...I'm pretty close if not spot on, but as always I leave my options open. There might be a lone wolf frequency out there so I will continue my searching.

Just a quick update...programmed only 2 sites...RAN-6 (Sears or Willis or what ever Tower) and RAN-24 (Midway). I locked out the others, eliminated the control channel frequency and programmed as NXDN-C. Let's see how this goes...

 

[werinshades]

Just a quick update...programmed only 2 sites...RAN-6 (Sears or Willis or what ever Tower) and RAN-24 (Midway). I locked out the others, eliminated the control channel frequency and programmed as NXDN-C. Let's see how this goes...

I've been monitoring the NXDN system this way and from what I can tell, have not missed many transmissions. The more I experiment, the more I believe NXDN systems behave very similar to LTR systems.In my scenario, some of the licensed frequencies are FB-6 while others are FB-8. The research I've done tells me the some of these have control channels while others don't. This just adds to the challenge as I'm really not hearing or seeing a difference if I program NXDN-C or NXDN-D. On the RAN-6 frequencies, I'm aware of one active control channel, and I don't think the scanner recognizes control channels.

My experiment was holding on an active talk group to see if the scanner will "follow" the conversation. From all appearances, it does. This is programmed as NXDN-C, no active control channel in the Sites and 2 RAN's programmed as I described. From what I can tell, simply programming as NXDN would suffice. This is only 1 system, so I can't say this is definitive. Just curious what others have discovered?

 

[RRR]

How many of you saw the title of this thread and got a little excited thinking Uniden had finally gotten NXDN? ;-)

 

[werinshades]

My experiment was holding on an active talk group to see if the scanner will "follow" the conversation. From all appearances, it does. This is programmed as NXDN-C, no active control channel in the Sites and 2 RAN's programmed as I described. From what I can tell, simply programming as NXDN would suffice. This is only 1 system, so I can't say this is definitive. Just curious what others have discovered?

Just an update..I've been using this method and "appears" to be successful. The only difference is I programmed the "known" RAN-6/Sears Tower control channel of 472.7125. I also added 2 additional RAN-24/Midway Airport frequencies, which do not have an active control channel. I created a Scan List for the Wild Card (99) so I can turn that on and off at my discretion. The RAN's are programmed separately as been suggested.

My findings have been positive from what I can tell. If I get an active talk group on my Wildcard scan list, I can "hold" the talk group and hear both sides of the conversation. I have taken into consideration that some companies have separate talk groups for base/mobile but that appears to be an exception and not the rule so far.

So back to my Midway Shuttle Bus/Rental Car transport companies. As I previously stated, these are run by two different transportation companies with two separate talk groups. I know it's not very exciting listening, and have my TRX-2 dedicated to NXDN so I'm not missing anything. I originally tried programming "only" the RAN-6/Sears Tower frequencies and from what I was able to tell, I was receiving all talk groups. But I did notice the Employee Shuttles talk group was active as always, but the Rental Car Shuttles talk group was silent. Previously I tried it the other way around and locked out all the talk groups except RAN-24/Midway and the opposite occurred..Rental Car Shuttles shuttles were active and the Employee Shuttles talk group was silent. I waited a half hour and finally unlocked RAN-24 and the rental Car Shuttle talkgroup was active again.

I thought, "how could this be"? After some You Tube research, I found this: https://www.youtube.com/watch?v=r2e9DsSo2DU

I was not aware that this could be done, but then I thought I'm sure it's possible on most multi-site trunking system. Since it's local, it would make sense if not alot of activity on the frequencies, but if it's busy this might not be very beneficial. Anyway...I'm not the radio guru so as it may be.

Been listening to this system using two sites (RAN-6/RAN-24), been hearing two sides of most conversations...yes I know radio etiquette is not always the best, and have been tagging talk groups and verifying users. It's been quite the learning curve, but I knew I'd be able to understand this eventually. Patience is the operative word here...good luck to all going at this.

 

[troymail]

Just an update..I've been using this method and "appears" to be successful. The only difference is I programmed the "known" RAN-6/Sears Tower control channel of 472.7125. I also added 2 additional RAN-24/Midway Airport frequencies, which do not have an active control channel. I created a Scan List for the Wild Card (99) so I can turn that on and off at my discretion. The RAN's are programmed separately as been suggested.

My findings have been positive from what I can tell. If I get an active talk group on my Wildcard scan list, I can "hold" the talk group and hear both sides of the conversation. I have taken into consideration that some companies have separate talk groups for base/mobile but that appears to be an exception and not the rule so far.

So back to my Midway Shuttle Bus/Rental Car transport companies. As I previously stated, these are run by two different transportation companies with two separate talk groups. I know it's not very exciting listening, and have my TRX-2 dedicated to NXDN so I'm not missing anything. I originally tried programming "only" the RAN-6/Sears Tower frequencies and from what I was able to tell, I was receiving all talk groups. But I did notice the Employee Shuttles talk group was active as always, but the Rental Car Shuttles talk group was silent. Previously I tried it the other way around and locked out all the talk groups except RAN-24/Midway and the opposite occurred..Rental Car Shuttles shuttles were active and the Employee Shuttles talk group was silent. I waited a half hour and finally unlocked RAN-24 and the rental Car Shuttle talkgroup was active again.

I thought, "how could this be"? After some You Tube research, I found this: https://www.youtube.com/watch?v=r2e9DsSo2DU

I was not aware that this could be done, but then I thought I'm sure it's possible on most multi-site trunking system. Since it's local, it would make sense if not alot of activity on the frequencies, but if it's busy this might not be very beneficial. Anyway...I'm not the radio guru so as it may be.

Been listening to this system using two sites (RAN-6/RAN-24), been hearing two sides of most conversations...yes I know radio etiquette is not always the best, and have been tagging talk groups and verifying users. It's been quite the learning curve, but I knew I'd be able to understand this eventually. Patience is the operative word here...good luck to all going at this.

Two different users, different talkgroups, different RAN values - same frequency? Sounds like two different licensed users licensed for the same frequency(ies)... two different systems?

 

[werinshades]

Two different users, different talkgroups, different RAN values - same frequency? Sounds like two different licensed users licensed for the same frequency(ies)... two different systems?

Nope...same "licensed" user. Same talk groups, same UID's are coming up on RAN-24 frequencies. Just not the Employee Shuttles. Now you see what I'm up against...lol!

http://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=3630903

451.84375, 451.85625, 452.88125 have been confirmed via search. I've held on the other 2 and have not had other activity.

Check out (A Beep LLC)..you'll see a bunch of available frequencies.

 

[EricCottrell]

Just an update..I've been using this method and "appears" to be successful. The only difference is I programmed the "known" RAN-6/Sears Tower control channel of 472.7125. I also added 2 additional RAN-24/Midway Airport frequencies, which do not have an active control channel. I created a Scan List for the Wild Card (99) so I can turn that on and off at my discretion. The RAN's are programmed separately as been suggested.

My findings have been positive from what I can tell. If I get an active talk group on my Wildcard scan list, I can "hold" the talk group and hear both sides of the conversation. I have taken into consideration that some companies have separate talk groups for base/mobile but that appears to be an exception and not the rule so far.

So back to my Midway Shuttle Bus/Rental Car transport companies. As I previously stated, these are run by two different transportation companies with two separate talk groups. I know it's not very exciting listening, and have my TRX-2 dedicated to NXDN so I'm not missing anything. I originally tried programming "only" the RAN-6/Sears Tower frequencies and from what I was able to tell, I was receiving all talk groups. But I did notice the Employee Shuttles talk group was active as always, but the Rental Car Shuttles talk group was silent. Previously I tried it the other way around and locked out all the talk groups except RAN-24/Midway and the opposite occurred..Rental Car Shuttles shuttles were active and the Employee Shuttles talk group was silent. I waited a half hour and finally unlocked RAN-24 and the rental Car Shuttle talkgroup was active again.

I thought, "how could this be"? After some You Tube research, I found this: https://www.youtube.com/watch?v=r2e9DsSo2DU

I was not aware that this could be done, but then I thought I'm sure it's possible on most multi-site trunking system. Since it's local, it would make sense if not alot of activity on the frequencies, but if it's busy this might not be very beneficial. Anyway...I'm not the radio guru so as it may be.

Been listening to this system using two sites (RAN-6/RAN-24), been hearing two sides of most conversations...yes I know radio etiquette is not always the best, and have been tagging talk groups and verifying users. It's been quite the learning curve, but I knew I'd be able to understand this eventually. Patience is the operative word here...good luck to all going at this.

Hello,

It is also possible for the radio shop to lock a radio to a site via the code plug programing. The user can not change it and the radio will not roam. The radio shop can program the Rental Shuttle radios to only use Site 24 since they shuttle around Midway Airport. The employee shuttles may go father off-airport so they use Site 6 instead.

73 Eric

 

[werinshades]

Hello,

It is also possible for the radio shop to lock a radio to a site via the code plug programming. The user can not change it and the radio will not roam. The radio shop can program the Rental Shuttle radios to only use Site 24 since they shuttle around Midway Airport. The employee shuttles may go father off-airport so they use Site 6 instead.

73 Eric

That would be my suspicion as well, and the video mentions a "spur site" and "locking on a site". I have found many users, most appear to roam. I also had to set the talk group delay a little longer as I've noticed many users aren't "quick keyers".

 

[Mojaveflyer]

NXDN Trunked System

If I'm reading this correctly, I should enter the frequencies in the software as the LCN frequencies, not as conventional freqs. Right? Also, My EZ-Scan software asked NXDN "C" or "D". I'm guessing "C"... Right?

 

[werinshades]

If I'm reading this correctly, I should enter the frequencies in the software as the LCN frequencies, not as conventional freqs. Right? Also, My EZ-Scan software asked NXDN "C" or "D". I'm guessing "C"... Right?

I really can't answer that as it appears each system might be different. I'm monitoring a large NXDN system with many different sites, but only 7 I can monitor from my location. In my case, based upon the suggestions I have limited my monitoring to two different sites and I am following conversations. The frequencies are not entered in any specific order, and yes NXDN-C is what I used.

 

[Mojaveflyer]

NXDN Trunk System At TTC

The system I'm attempting to monitor has 10 frequencies and two sites on VHF in the railroad band.

Thanks!