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Voice/Control Channel Decoding Software - For discussion of software applications which decode digital voice formats and trunking control channels. Please use the HF Digital Signals forum for anything below 30MHz.

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  #41 (permalink)  
Old 01-02-2017, 12:33 AM
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Hey all,

Got a system in my area which is exhibiting something weird which I'm curious about.

Got a NEXEDGE96 system I'm monitoring with the latest DSDPlus fastlane release. I've seen this activity from this system with older releases too, however, so I don't think this is a DSD quirk.

Every forty seconds, there is a "Registration Req" for a particular radio. That RID comes back registering on the same talkgroup every time. About once in a hundred times it might fail to register, but succeeds again on the next go-around.

Two questions:

1. Is "Registration Req" aka AUTH_INQ_REQ a command (demand) from the system for a radio to register/affiliate? In other words:

Code:
Sync:+NXDN96 TB CCDATA       AUTH_INQ_REQ     Visitor Src=65520 SU=2915 Parm=459C Tgt HomeSystem=200
Is the above "the system" (the infrastructure for sys 200) demanding that RID 2915 make an attempt to affiliate to a talkgroup?

Is there anything of interest in the source ID or the "Parm" data there that will help me understand why this is being asked for every 40 seconds? (Is source 65520 the ID for the radio network, like 16777213 is for a P25 system?)

The response, when successful, is invariably:

Code:
Sync:+NXDN96 TB CCDATA       REG_RESP         HomeSystem=200 SU=2915 Group=99 ACCEPTED
2. What would be the rationale for demanding a registration so often from one specific radio that doesn't move onto another talkgroup? Is this some kind of heartbeat check, with absence of the response indicating that something is wrong with the system (kind of like a less intense version of British subs checking for reception of BBC Radio 4)?

This site is the only one I can reach from my home base and rarely has voice traffic, so I don't know what if anything is carried on 99. For all I know it could be the emergency button activation channel (does NXDN have that capability - forcing a radio to a specific TG when the emergency button is hit?) and the radio could be the in-control-center mobile used to monitor that channel for emerg calls.
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  #42 (permalink)  
Old 01-02-2017, 1:20 AM
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I don't know, I don't use the DSD.

What I can tell you from running a NexEdge system and looking at logs...

1. Could be a radio dropping out of range momentarily. When the radio looses it's connection to the system it'll reconnect. It is doing it pretty frequently, not sure how long it'll hold it's registration. In other words, it should do this just because it lost connection for a few seconds.

2. You can set up radios to send in their GPS location. Usually it's done on either the control channel or on a traffic channel (depends on how it's set up). You can set up the radio to do it's GPS location sent out on a conventional channel. Could be it switches to a conventional channel, sends it's location, switches back to the trunked system

3. Could just be set up wrong.

4. Might be low battery. The radios will cycle on and off when the battery hits a certain point, before it completely dies.
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Old 01-02-2017, 6:19 PM
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I was skeptical of this being some kind of accidental issue since it was 40 seconds on the dot that it repeated at. I say 'was' because as of this morning it's no longer doing this. I wonder if I should wave hi to the system manager lurking this forum?
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Old 01-02-2017, 9:17 PM
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Hello,


I read a little bit about this. We do not get a good picture of things because we do not have what the mobile unit is doing. Either the mobile is requesting registration or the trunk system is requesting authentication.

AUTH_INQ_REQ is used to request Authentication and the mobile unit sends back Authentication data. It can also be used by a conventional repeater for Authentication. In Type-C trunking it is used to start Authentication after the Registration Request.

The 40 seconds spacing could be a timeout. It could be the mobile unit was in a location where it could receive the AUTH_INQ_REQ and respond back, but kept missed the REG_RESP. I had seen something similar when receiving a weak control channel where certain messages always errored.

73 Eric
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Old 01-06-2017, 12:07 PM
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Hi Eric (et al), got another question but it is more about conventional than trunking - hope you'll allow it.

Just picked up two-tone paging tones on a conventional NXDN channel. It's 100% for certain that this is not a crosspatch with an analog channel somewhere - only NXDN capable receivers are going to be picking up this signal. Do NXDN radios support 2 tone decode in digital mode, or is it more likely that this agency is just using the tones as a noisemaker/attention-getter?

Thanks!
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Old 01-06-2017, 5:14 PM
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I have also heard 2-tone on DMR systems as well.

Sent from my SM-G900W8 using Tapatalk
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Old 01-06-2017, 6:51 PM
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Nothing unusual about two tone signalling. Tone frames are built into the AMBE spec. It doesn't see a lot of use though.

Also, re your IDAS system frequencies - why wouldn't you use a calibrated SDR to nail down the exact frequencies? 143.11 vs 143.1125 is a difference of 2.5 kHz, no? That's easily resolvable on a spectrum display.
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Old 02-20-2017, 4:09 PM
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Has anyone else observed a Nexedge48 trunk system operating as a single channel trunk? I'm watching a site on a multi site trunk system. This particular site has very little traffic, in fact I've only observed one user so far. I have all of the channels for the site programmed into DSD, but the site seems to use the control channel as the only voice channel.
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Old 02-20-2017, 4:13 PM
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Quote:
Originally Posted by garys View Post
Has anyone else observed a Nexedge48 trunk system operating as a single channel trunk? I'm watching a site on a multi site trunk system. This particular site has very little traffic, in fact I've only observed one user so far. I have all of the channels for the site programmed into DSD, but the site seems to use the control channel as the only voice channel.
I'm pretty sure I've seen this on a system in my area. Are you in Maryland? Sure sounds similar....
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Old 02-20-2017, 4:17 PM
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No, not Maryland. I'm just curious because I don't recall seeing any mention of this before.

Quote:
Originally Posted by troymail View Post
I'm pretty sure I've seen this on a system in my area. Are you in Maryland? Sure sounds similar....
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Old 02-20-2017, 4:18 PM
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I see lots of "weird" NXDN stuff around here....
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Old 02-20-2017, 4:26 PM
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There is far more DMR and MotoTrbo around here than NXDN. One thing that is weird is that the private ambulance service I'm hearing has three divisions. One is on this NXDN system, the other two are on a MotoTrbo trunked network.

I have no idea why they did it that way.

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Originally Posted by troymail View Post
I see lots of "weird" NXDN stuff around here....
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Old 02-20-2017, 9:35 PM
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Quote:
Originally Posted by garys View Post
Has anyone else observed a Nexedge48 trunk system operating as a single channel trunk?
Not a system, but a site or two.


Quote:
I'm watching a site on a multi site trunk system.
OnQue.


Quote:
This particular site
St. Mary's? Bonnville? Dashwood? Some other composite control channel OnQue site?


Quote:
has very little traffic, in fact I've only observed one user so far. I have all of the channels for the site programmed into DSD, but the site seems to use the control channel as the only voice channel.
All the channels? I'd think that a CCC site would only have one.


Quote:
Originally Posted by garys View Post
There is far more DMR and MotoTrbo around here than NXDN. One thing that is weird is that the private ambulance service
Spectrum Patient Services.


Quote:
I'm hearing has three divisions. One is on this NXDN system,
OnQue.


Quote:
the other two are on a MotoTrbo trunked network.
GOTRBO? FleetConnect?
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Old 05-31-2017, 9:57 PM
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Default NXDN Issues

OK, bear with me, as I'm a total NOOB when it comes to NXDN.

I do have a local system here in my town which appears to be a 4 channel NXDN4800 system. I've got DSD/FMP up and running, and it shows the following info in the scroll:

Sync:+NXDN48 TB CCDATA SRV_INFO Category=Local System=2029 Site=16 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl

Sync:+NXDN48 TB CCDATA ADJ_SITE_INFO Neighbor L2029-3 CC=384 4 Neighbors; L2029-7 CC=301 5 Neighbors; L2029-10 CC=380 6 Neighbors

First of all, the RR database shows SYSID 2029 as a NXDN9600 baud system, not a 4800. But here's the thing. DSD shows that my neighbouring system is "L2029", which shows as a 4800 system. Weird. Data base shows that L2029 and 2029 are connected to each other.

Can a 4800 system interconnect with a 9600 system, or is something wrong with one of the entries?



When there is a voice tranmission, I get the following:

Sync:+NXDN48 TB CCDATA VCALL_ASSGN Group Call 4800 bps/Half Rate Tgt=10023 Src=10256 Timer=60s Chan=148

In the above data, I undertand that the Tgt=10023 is the talkgroup, while the Src=10256 as the radio ID calling. In the previous posts, I see that the number 0 is a place holder. Does that mean the talkgroup is actually 1256? Or is it 256. Or just 10256?



OK, and third question. What are colours, where can I find them and what do they mean? I've searched the forums, threads and google but can't seem to find an answer that makes sense. From what I gather, they are sort of a CTCSS or NAC code specific to a talkgroup or radio. Are they used on trunked systems, or just single channel DMR?


And fourth question: I got a the code and installed the DMR update for my brand new BCD436HP. I've programmed in (I think), this system that I'm monitoring as both a trunked system, and as a conventional system. Nothing. When I manually tune one of the voice frequencies into the scanner, I get nothing but digital static noise, no decode. Is something wrong with my set up? This system decodes voice just fine on the computer, but not on the radio.


Sorry for the noob questions, but I've searched the forums and online and can't seem to figure it out.
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Old 05-31-2017, 10:10 PM
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The talkgroup is 10023, and Uniden doesn't make a scanner that does NXDN... Only Whistler has that currently.
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Old 05-31-2017, 10:37 PM
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Thanks! That would explain it! :-)

Quote:
Originally Posted by Forts View Post
The talkgroup is 10023, and Uniden doesn't make a scanner that does NXDN... Only Whistler has that currently.
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Old 06-01-2017, 6:17 AM
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I thought there was a download available for BCDx36HP Nexden?
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Old 06-01-2017, 7:35 AM
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Quote:
Originally Posted by bcradio View Post
OK, bear with me, as I'm a total NOOB when it comes to NXDN.

I do have a local system here in my town which appears to be a 4 channel NXDN4800 system. I've got DSD/FMP up and running, and it shows the following info in the scroll:

Sync:+NXDN48 TB CCDATA SRV_INFO Category=Local System=2029 Site=16 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl

Sync:+NXDN48 TB CCDATA ADJ_SITE_INFO Neighbor L2029-3 CC=384 4 Neighbors; L2029-7 CC=301 5 Neighbors; L2029-10 CC=380 6 Neighbors

First of all, the RR database shows SYSID 2029 as a NXDN9600 baud system, not a 4800. But here's the thing. DSD shows that my neighbouring system is "L2029", which shows as a 4800 system. Weird. Data base shows that L2029 and 2029 are connected to each other.

Can a 4800 system interconnect with a 9600 system, or is something wrong with one of the entries?



When there is a voice tranmission, I get the following:

Sync:+NXDN48 TB CCDATA VCALL_ASSGN Group Call 4800 bps/Half Rate Tgt=10023 Src=10256 Timer=60s Chan=148

In the above data, I undertand that the Tgt=10023 is the talkgroup, while the Src=10256 as the radio ID calling. In the previous posts, I see that the number 0 is a place holder. Does that mean the talkgroup is actually 1256? Or is it 256. Or just 10256?



OK, and third question. What are colours, where can I find them and what do they mean? I've searched the forums, threads and google but can't seem to find an answer that makes sense. From what I gather, they are sort of a CTCSS or NAC code specific to a talkgroup or radio. Are they used on trunked systems, or just single channel DMR?


And fourth question: I got a the code and installed the DMR update for my brand new BCD436HP. I've programmed in (I think), this system that I'm monitoring as both a trunked system, and as a conventional system. Nothing. When I manually tune one of the voice frequencies into the scanner, I get nothing but digital static noise, no decode. Is something wrong with my set up? This system decodes voice just fine on the computer, but not on the radio.


Sorry for the noob questions, but I've searched the forums and online and can't seem to figure it out.
Hello,

L2029 is the same as Local 2029, so the neighbors are on the same system. The RRDB System ID does not show the system category. You are receiving Site 16, which in the RRDB shows a miles away from Victoria, BC. This maybe another system using the same System ID.

The talkgroup is 10023.

DMR and NXDN are two separate digital systems. DMR uses colors and NXDN uses RAN. You are receiving a trunking system so the RAN value will be the site number modulus 64.

It would be better to start a thread about this WTS NXDN system in the Prairies and Pacific Coast forum so other monitors in your area can help.

73 Eric
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Old 06-01-2017, 6:38 PM
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Thanks, Eric! Will do!

Quote:
Originally Posted by EricCottrell View Post
Hello,

L2029 is the same as Local 2029, so the neighbors are on the same system. The RRDB System ID does not show the system category. You are receiving Site 16, which in the RRDB shows a miles away from Victoria, BC. This maybe another system using the same System ID.

The talkgroup is 10023.

DMR and NXDN are two separate digital systems. DMR uses colors and NXDN uses RAN. You are receiving a trunking system so the RAN value will be the site number modulus 64.

It would be better to start a thread about this WTS NXDN system in the Prairies and Pacific Coast forum so other monitors in your area can help.

73 Eric
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Old 07-22-2017, 2:11 PM
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I'm monitoring a NXDN trunk system which is part of a network in eastern MA. One site seems to operating as a single frequency trunk as the control channel data is also a voice channel.

Has anyone else seen that sort of activity?
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