Motorola DMR Tier III CapMAX

[CDTbolt10033]

Hello,

The system I am monitoring is a  Motorola DMR Tier III Capacity Max system and I listen to it through DSD Plus since SDR-Trunk for some reason does not decode it properly. I have a question regarding the control channel of DMR Tier III. What happens when the control channel uses both timeslots on the frequency? When group calls come in, it shows two table lines for timeslot 1 and timeslot 2 for the voice frequency, but it doesn't seem to work correctly. The group call durations show either 0.1 or 0.0, and the command prompt displays "Audio Segment detected with NO TO identifiers". As a result, the TGs do not record. 

Any thoughts on this?

[sdrtrunk]

Can you please make a bitstream recording, or a couple, of the control channel and send to me so that I can troubleshoot?

Denny

[CDTbolt10033]

Here is the demodulated bitstream (.bits)

Let me know if you need more data.

[CDTbolt10033]

The system isn't very busy, the users of the system are the county fire dept and public works.

[CDTbolt10033]

The group call does come in and I get voice but the duration and recording do not work. The duration of group calls will be 0.0 or 0.1 in length.

[sdrtrunk]

I opened an issue here: https://github.com/DSheirer/sdrtrunk/issues/1787

[CDTbolt10033]

Ok, I also have this one I opened a while ago: https://github.com/DSheirer/sdrtrunk/issues/1740

[sdrtrunk]

From the recording that you posted, it looks like the system is using RAS ... what an annoying feature.  Let me see if I can do anything to enable sdrtrunk to automatically 'fix' this.

Denny

[CDTbolt10033]

Thanks a lot for looking into this matter. :-D

[sdrtrunk]

I just merged some code changes into master here: https://github.com/DSheirer/sdrtrunk/pull/1793

This adds a feature to auto-correct CSBK control messages when the system is using 'alternate' CRC mask values.  Based on what I'm seeing in the example recording that you sent, this CapMax system is using different CRC mask values in each timeslot, and even within the same timeslot there were 6x different alternate mask values used.  I guess one could ask 'How can you be sure?' that the alternate mask value is valid?  Statistically, there were over 300 identical messages with identical CRC checksums for each of the 6x different alternate mask values that I saw.  It seems like they're using different CRC mask values for each distinct message content.  On a control channel the messages are repeated continuously, so you can statistically track and auto-correct these values.  However, on lower frequency messages, this becomes problematic to collect enough examples to say definitively that the alternate mask value is correct.  This all makes me scratch my head and wonder how they're actually implementing this.  A puzzle to ponder for sure.

Anyway, these changes may not resolve the original issue that @CDTbolt10033 reported.  I'll need some more bitstream recordings that contain voice calls so that I can further test this.

Denny 

[CDTbolt10033]

Here is another bits recording when talkgroups are active.

[CDTbolt10033]

Here are some more bitstream recordings from Site 9 with talkgroup activity. 

[sdrtrunk]

I just merged some more changes that should allow MotoTRBO systems with RAS enabled to be processed: https://github.com/DSheirer/sdrtrunk/pull/1794

@CDTbolt10033 if you have a chance, could you pull down the nightly release and run that against this system to see if it follows your Capacity Max system more accurately?  I added support for 2x additional message types but I'm not sure I got the channel number parsing correctly.  Can you confirm that the control channel is allocating the traffic channels on the correct frequency and that you're hearing group calls when they happen on timeslot 1 or on timeslot 2?

Thanks,

Denny

[sdrtrunk]

One additional point ... you need to turn on the 'Ignore CRC Checksums' option in the DMR channel configuration in the playlist editor so that the decoder will ignore the invalid CRC checksums and use all of the messages to keep track of the system call state.

[CDTbolt10033]

It seems to be somewhat working as before I had a talkgroup range set to blacklist talkgroups I don't want to listen to and before it would not work and would still allow talkgroups to play now it does work however the group call duration still isn't functioning properly.

[CDTbolt10033]

Update: I see the talkgroups now record! Just the SDR-Trunk table does not show the duration properly.

[sdrtrunk]

I'm on vacation this week in Tucson and I found a system configured just like yours .... CapMax running in Advantage mode with RAS enabled.  I'll test against the system over the next couple days to make sure it's working good.  I made more changes this morning that allow the calls table to update the call duration ... so far I'm not able to distinguish between TS1 or TS2 for where the call is taking place, so that complicates things, but as soon as I figure it out, I'll make the code changes and push them to master.

https://www.radioreference.com/db/sid/11333

Denny

[CDTbolt10033]

The calls on the events table still do not update and they show 0.0 or 0.1 or nothing as the duration. Also, some of the RID aliases names/icons don't show when they register on the system on the events table.

[sdrtrunk]

I found another large Capacity Max system here in Tucson for the Sahuarita Mine that's similar to the examples you sent.  They're also sending GPS positions for the mine vehicles.  I think I have the calls and call duration issue resolved but I have to test against some Cap+ and Con+ systems to make sure i didn't break anything in the process.  Once testing is complete, I'll push these changes to master

[CDTbolt10033]

Okay, sounds good.

[sdrtrunk]

The changes are merged into master.  You can try them out via the nightly build.

Please let me know if this resolves the issue, or if you're still seeing problems?'

Denny

[CDTbolt10033]

The duration and the FROM xxxxxx, Radio Alias are working, and the neighbouring sites show correctly too. The only thing that does not seem to be working correctly, and I am unsure if that is how it works, is that the FROM aliases I have on the playlist do not show up when their alias registers on the system.  

[CDTbolt10033]

I should also mention I am getting some Channel Grant - No Frequency - Check Playlist Channel Config once in a while. 

[CDTbolt10033]

Never mind I think the No Frequency is due to a weak signal with other sites out further.

[CDTbolt10033]

Again nevermind it's an actual issue, even on a strong local site it says No Frequency sometimes.

[CDTbolt10033]

Ok, I am noticing some issues with the FROM and as mentioned before the No Frequency issue.
I am monitoring two sites one site is my local site (top) and the other site (bottom) is the site that catches the whole county fire dept. Sometimes I can hear them on my local site but then their radios switch to their site (bottom) and I don't hear it on my local site so I have to use the further away site.

The system I am monitoring: https://www.radioreference.com/db/sid/12626

[sdrtrunk]

I just pushed another change to master that should address the 'no frequency' issue and the Capacity Plus REST channel and channel rotation issues.

Please try the latest nightly build, once it recompiles in a few minutes.

[CDTbolt10033]

CapMax on this change has an issue where the TG with a call has multiple like its the duration

[CDTbolt10033]

Still have some No Frequency and also an issue with the duration going wild at an odd time (which rarely happens). Duration of 10572.0