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SDR# TETRA Demodulator Trunk Tracking Demonstration

Joined
Nov 22, 2016
Messages
511
Just another note when recording IQ samples.
Make sure that the target frequency is centered in SDR#.

To the DMO users:
Can private calls be made on MS to MS and also on DM-REP or can you only do group calls.
I would like to see IQ samples of both of the above if possible please. This may help with displaying information in the plug-in.

Thanks.
 
Joined
Feb 8, 2019
Messages
11
Record with SDR# and the IFRecorder plug-in.
Set IFRecoder with "16 bit PCM IQ" and set your output folder.
Normally setting SDR# for WFM is required, but NFM will yield a smaller file size (and/or longer recording for same size)
NFM will be OK to use for the plug-in in future versions.
Do not change the file name, as this is required for better playback of sample with in SDR#.



In the standards (EN100-392-15), section "6 Duplex spacing" shows that with a frequency band of 400MHz and when the "Duplex Spacing" element is = 0, the spacing is 10MHz. When element is = 1 then it is 7Mhz.

I will check the code to see if anything is out there as well.
Lets see if this worked.

Dropbox - 13-09-18_438212kHz.wav
 
Joined
Nov 22, 2016
Messages
511
OK have downloaded. All seems to playback OK. Not much going on there but it worked all the same.
Had me scratching my head at first. Thought it was DMO.
That is some old gear. Based on 1st edition of the TETRA standards.
Still shows as Duplex spacing = 0.
The original standards also show the same values as stated earlier.
 
Joined
Feb 8, 2019
Messages
11
OK have downloaded. All seems to playback OK. Not much going on there but it worked all the same.
Had me scratching my head at first. Thought it was DMO.
That is some old gear. Based on 1st edition of the TETRA standards.
Still shows as Duplex spacing = 0.
The original standards also show the same values as stated earlier.
Sorry about that, there is testing going on around here with both DMO 1A rep and TMO. But only one at a time (same tx freq of the repeater).
I'll try to grab some samples for DMO once that is on the air again.

The TMO hardware is a Motorola MTS2. It is quite possible it is running older code (big ??, as I have not seen it from nearby, only on pictures).

I'll see if I can get some more and foremost more interesting samples. I was the only one available on the net. Currently only 3 people have their MS programmed for TMO. A lot more have DMO capability so once that is back in the air I can probably get you more interesting samples. Incl GPS long/short messages etc.
 
Joined
Nov 22, 2016
Messages
511
Sorry about that, there is testing going on around here with both DMO 1A rep and TMO. But only one at a time (same tx freq of the repeater).
I'll try to grab some samples for DMO once that is on the air again.

The TMO hardware is a Motorola MTS2. It is quite possible it is running older code (big ??, as I have not seen it from nearby, only on pictures).

I'll see if I can get some more and foremost more interesting samples. I was the only one available on the net. Currently only 3 people have their MS programmed for TMO. A lot more have DMO capability so once that is back in the air I can probably get you more interesting samples. Incl GPS long/short messages etc.
No problems, Do what you can when you can. No rush.
 
Joined
Feb 27, 2009
Messages
110
Location
LA
Just another note when recording IQ samples.
Make sure that the target frequency is centered in SDR#.

To the DMO users:
Can private calls be made on MS to MS and also on DM-REP or can you only do group calls.
I would like to see IQ samples of both of the above if possible please. This may help with displaying information in the plug-in.

Thanks.
Yes, in DMO and DMO-REP mode you can make a private calls by dialing ISSI and pressing PTT. It also works via repeater same way.
 
Joined
Dec 15, 2014
Messages
67
Location
Copenhagen
I have now manage to create a DMO - DMO in Private Call. The first call has radio 2 return in Group Call.
This was done becouse radio 2 did not response in a time limet.
But the second Call response as Private Call. Both Calls is recived fine with TTT.
The other files is some Test in DMO SDS send to radio 2. I have not seen if SDS is decoded.
This was all done on a DMO Repeater.
21-57-22_428500kHz.wav and 2 more files
 
Last edited:
Joined
Nov 22, 2016
Messages
511
I have now manage to create a DMO - DMO in Private Call. The first call has radio 2 return in Group Call.
This was done becouse radio 2 did not response in a time limet.
But the second Call response as Private Call. Both Calls is recived fine with TTT.
The other files is some Test in DMO SDS send to radio 2. I have not seen if SDS is decoded.
This was all done on a DMO Repeater.
21-57-22_428500kHz.wav and 2 more files
Downloaded, Thanks ozjua(y)

Have not added SDS other than to acknowledge it's presence.
I'm hoping TMO/DMO share the same SDS protocol.
While I don't think your samples use it, I have not added the handling for fragmented PDUs in DMO.
TSSDRs has added the code for fragmentation in DMO, I just haven't added it to my code as of yet.
Probably very long SDS messages will use fragmented PDUs so I may ask for a IQ sample of that sometime.

Thanks again for supplying these IQ samples.
 
Joined
Nov 22, 2016
Messages
511
@oz1jua

It does seem for the most part that the code for TMO SDS will work with DMO SDS.

However when I play these DMO SDS IQ samples you provided, the DM_SDS_UDATA PDUs is seen but the protocol identifier element (the part that determines if text message or GPS locations or other) is a reserved type (i.e unknown).

When I look at the buffer where the SDS is stored, nothing but zero's follow for the length of the message.

When you send a SDS message, does the receiving MS receive/display it?

I know the code used for TMO SDS is OK and I have rechecked the code for DMO SDS that proceeds it, and it seems OK.
Not sure what's been missed here.
 
Joined
Mar 23, 2014
Messages
281
Help Wanted
Please anyone who have a TTT running in both Single Mode or Dual Mode after some period, the SDR# screen seem Crash.
(some after short period running, some after several hours or longer)
When this Crash is happen on your system, Please be so helpfull report any SDR# crash to Wraith2008.
What file version you are using?
File size + File date
SDRSharp.Tetra.dll
libtetradec.dll
tetra_trunk_tracker.exe

.
 
Joined
Nov 22, 2016
Messages
511
Help Wanted
Please anyone who have a TTT running in both Single Mode or Dual Mode after some period, the SDR# screen seem Crash.
(some after short period running, some after several hours or longer)
When this Crash is happen on your system, Please be so helpfull report any SDR# crash to Wraith2008.
What file version you are using?
File size + File date
SDRSharp.Tetra.dll
libtetradec.dll
tetra_trunk_tracker.exe

.
It also should be noted that the crash he refers to is "type System.OutOfMemoryException."
Any other crash type will be unrelated to his issue.
 
Joined
Sep 8, 2006
Messages
2,764
Location
Stockholm, Sweden
It crashes and freezes but no big deal, I just restart again. I often get variations of "error 58, File already exists". Probably something related to the recordings.

/Ubbe
 
Joined
Mar 7, 2018
Messages
17
Hello regarding to TETRA DMO in the net info column bursttype it shows TCH/F voice FN:03TN4 traffic. Im not hearing any sound, is this indication of DMO signal or some false positive?
 
Joined
Nov 22, 2016
Messages
511
Hello regarding to TETRA DMO in the net info column bursttype it shows TCH/F voice FN:03TN4 traffic. Im not hearing any sound, is this indication of DMO signal or some false positive?
Is timeslot 1 selected (not using auto)
Are you seeing these stream down the screen or just 1 or 2 at a time.
Using the plug-in option "Stronger burst detection" can help reduce false/positives a lot in DMO.
DMO is more prone to false/positives because of the gaps in transmission, that's part of the reason I added the above option.
The other reason is when using TTT in dual mode and the VC SDR# is sitting idle, it is on a empty frequency which causes the plug-in to falsely think there valid bursts. This is seen as timeslots becoming active (show red).
 
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