Strange DMR Channel with DSDPlus FastLane

[BrinC]

Hi there all! Long time reader here; for years, and I learned a lot. Now I an facing a strange and interesting DMR channel which prompted me to post.

I am using the latest DSDPlus FastLane release and everything works fine decoding many DMR channels in my area and a P25 Simplex (I think) channel - but the P25 is for another post.

The DMR Channel in question is mainly data on DCC-1 and sometime Voice on DCC-5. It is strange because I cannot understand what kind of data is being sent. If it is some kind of telemetry or messaging then I am not interested at all, but if it is some kind of control channel then I am interested if I can understand the topografy of the network. Mainly there is data traffic, some time only voice, and sometimes data+voice. In the last scenario DSD+ goes mad and scrolls a lot of errors. No errors if it is only voice or only data. Voice decodes fine and clear - data scrolls without errors but I cannot understand what kind of data.

I've managed to record the raw input of DSD+ during an episode, which I uploaded to zippyshare @

Zippyshare.com - DSDPlus-Raw-Input_2017-09-10@151210.wav

Also I am attaching two screenshots. One of the signal on SDR# and the other of the DSD+ windows during the registration of the above audio file. On the second screenshot, the area with red rectangle on the DSD+ Event Log window is what it logs during the registration.

Is there anyone that can help me understand what kind of DMR Channel is this?

Thanks in advance,

Ben

 

[slicerwizard]

Zippyshare has jumped the shark. Pops up all kinds of junk. Couldn't even get it to let me download that file.

 

[BrinC]

Yep, @slicerwizard , just noticed today Zippy forces you to click endless times before letting you download the file.

Anyway, uploaded it to G-Drive:


https://drive.google.com/file/d/0B69B8tKwFdSvR3RDU1F3cTlIb00/view?usp=sharing


Thanks in advance!

Zippyshare has jumped the shark. Pops up all kinds of junk. Couldn't even get it to let me download that file.

 

[slicerwizard]

The DMR Channel in question is mainly data on DCC-1 and sometime Voice on DCC-5.

Looks like two separate transmitters (repeaters) to me.

It is strange because I cannot understand what kind of data is being sent. If it is some kind of telemetry or messaging then I am not interested at all, but if it is some kind of control channel then I am interested if I can understand the topografy of the network.

The DCC1 repeater seems to be sending automatic registration service (ARS) messages.

The DCC5 repeater is carrying voice traffic.

Mainly there is data traffic, some time only voice, and sometimes data+voice. In the last scenario DSD+ goes mad and scrolls a lot of errors.

Not surprising, since the two repeaters are fighting each other.

No errors if it is only voice or only data. Voice decodes fine and clear - data scrolls without errors but I cannot understand what kind of data.

Again, just some boring ARS data (based on the fact that the embedded port numbers are 0FA5 (4005), which is where ARS lives)

 

[BrinC]

@slicerwizard, Thank You very much for your help!

Yes, indeed there "were" two different repeaters. I mean "were" because it was my fault. I was using and old RTL-SDR USB Dongle and a not-tuned antenna. Your explanation made me think and I ordered a good usb dongle and a build a better antenna.

Last week I had all assembled and after some days of head-bashing I noticed that A repeater was on it's own frequency (almost all data and rarely some voice) and the B signal was a ghost/reflection/etc from another B repeater (all voice) on another frequency. I think it was because of the old RTL-SDR Stick and the antenna. Now everything is ok and believe it or not the error rate is below 1%, so, many many many thanks again.

Anyway, yes, you are right about ARS messages "living" on 4005, but it seems strange to me and I have reasons to believe these are not just simple ARS. I am prepping and uploading some fresh and cleaner logs and recordings as I write this post, and will post those logs and link, but I will try to explain:

On the channel I have seen only three active units. RID 8, 105 and 354. Also there is RID 1 which I believe is an USB accessory (because of 13.0.0.1), it is always passive, meaning it is always the target of data communications and never the source. Those data messages targeting RID 1 are with very short intervals; once a minute or max once every three minutes. It it was an Automated Registration Service, I think the unit sends one when powered on and does not sends every minute, right? Anyway, I will post the logs asap so I can bother you again looking into it