SDR# TETRA Demodulator Trunk Tracking Demonstration

[point2point]

Hi,

Thanks for looking into SDS , i get this message now when recieving GPS data.

 

[thewraith2008]

Same issue as before, I only see network info, but calls are not going to TTT

You will need to provide details of your set-up and possibly a screenshot showing it. (Send PM if you like)

What's your OS.
What version of SDR# you using.
What version of TTT and plug-in you using.
- no mixing of versions will work e.g. 'tetra_trunk_track.exe' and 'SDRSharp.Tetra.dll' must be from the same zip file (TTT_1.15.6_release.7z)
What mode is TTT been run in (Dual/Single)
What are the options used in TTT and the plug-in.

Maybe a timeline of what is occurring.



Latest version (v1.0.15.6) can be found here: Release post

 

[point2point]

What's your OS.

Windows 10 Prof (latest build)

What version of SDR# you using.

1700 (Latest)

What version of TTT and plug-in you using.

1.0.15.6
Latest plugins from 1.0.15.6
Tetra DLL from 15-4-2019

- no mixing of versions will work e.g. 'tetra_trunk_track.exe' and 'SDRSharp.Tetra.dll' must be from the same zip file (TTT_1.15.6_release.7z)

Correct

What mode is TTT been run in (Dual/Single)

Dual or single has same effect

What are the options used in TTT and the plug-in.

G = SDS on / LRRP( public) on or off
With SDS off problem is gone , but no results

Rest no options, only unchecked on at C

Maybe a timeline of what is occurring.

As soon as a message is there (in the CC - Network info) :

SDS_Data_Party with location data i get the popup.

 

[digiman1]

Small feature request if at all possible.

When selecting a group to hold, currently it is listing the GSSI, Could we have the Alpha Tag from the TETRA_GSSI.txt file listing the groups?

 

[thewraith2008]

Just an update to point2point's issue.

The error is related to when the following is seen for a SDS LIP(GPS) message:

Velocity:Horizontal speed is not known

A numeric value is expected here:

Velocity:10.0km/h

This is fixed for next release.

Small feature request if at all possible.

When selecting a group to hold, currently it is listing the GSSI, Could we have the Alpha Tag from the TETRA_GSSI.txt file listing the groups?

Space is a bit limited there.
I don't think both will fit and then I doubt a full 'Alpha Tag' will fit either.
I'll add it to the list and look into it sometime.



Latest version (v1.0.15.6) can be found here: Release post

 

[digiman1]

Space is a bit limited there.
I don't think both will fit and then I doubt a full 'Alpha Tag' will fit either.
I'll add it to the list and look into it sometime.

Good stuff! Cheers!

 

[kikosgc]

TetraDecoder without TTT running, you hear voice?
See calls in TetraDecoder Network Window?

Your Tetra signal SNR ?
SDR# AudioFilter OFF?

I have a similar case with a specific Group that doesn't go throw TTT... All others are fine... I'm thinking it's due to the way the call is setup.

 

[thewraith2008]

I have a similar case with a specific Group that doesn't go throw TTT... All others are fine... I'm thinking it's due to the way the call is setup.

Your quoting questions by 'hamradionl' saying that you have a similar problem. I don't understand.
If you are saying a group call does not play in TTT, check to see if GSSI is locked out.
Otherwise I will need to see the raw logs (TETRA_xc_xxxx.log) of the problem call or at IQ sample of the call not occurring.



Latest version (v1.0.15.6) can be found here: Release post

 

[hassanila]

@thewraith2008 Lately my SDR# v1.0.0.1700 (latest version) keeps crashing almost randomly, sometimes after 2h or upto 8hrs, it only happens when I'm using the Tetra Demodulator Plugin.
I have installed everithing that is required, (.NET, Visual C++)
I have attached crash.txt from SDR# folder and a link to the IQ sample (330MB).
The IQ file is around 5min and the error happens at the end of it (when SDR# crashes), you can use this plugin to skip to the end of the file.
It is probably an encoding problem because I live in Sweden and we use special characters,
I haven't assigned any names to any of the talkgroups in the Network Info Tab, so the problem must be coming from the network.

Also the audio sometimes cuts out for like 200ms (you can hear it in the sample too), what could the problem be?
I'm using a HackRF One with sample rate of 8MSPS and a powerful laptop, CPU usage 12%, SNR is 36dB

 

[thewraith2008]

Hi @hassanila97,

Thanks for the detailed report.

The problem is indeed a text encoding problem, but with the plug-in been the problem needing to use ISO/IEC 8859-14 Latin 8.
Problem is "ISO/IEC 8859-14 Latin 8" is not supported by the programming language.

I defined all the encodings used in the Tetra standards* for the "Text coding scheme" element but failed to test if they worked.
Two don't, "ISO/IEC 8859-10 Latin 6" and "ISO/IEC 8859-14 Latin 8"
* see EN300-392-2 - Table 29.29: Text coding scheme information element contents.

I will have to use "ISO/IEC 8859-1 Latin 1" for the encodings that are not supported.
The PDUs that use 'TextCodingScheme' element will still show the requested encoding, but will use the above stated encoding.
See maps for ISO/IEC 8859-1 and ISO/IEC 8859-14 for differences.

The crash occurs on this SDS message (because of 'TextCodingScheme'):

 SSI:1234567 D_SDS_Data Type:UDT-4 Length:1842 Protocol:Text_Messaging_TL MessageType:SDS-Transfer TextCodingScheme:Latin_8 TimeStampUsed:No TEXT:'' <---  Text not shown for clarity

This is fixed for next release which I will try and release soon.



Latest version (v1.0.15.6) can be found here: Release post

 

[thewraith2008]

@ hassinila97

Also the audio sometimes cuts out for like 200ms (you can hear it in the sample too), what could the problem be?

I don't think this is a plug-in problem. (I could be wrong of course)

My guess is, I think this maybe poor radio usage on the operators part.
They may not be leaving a sufficient lead-out delay before releasing the PTT.

The plug-in is more likely to miss something at start then at end.



Latest version (v1.0.15.6) can be found here: Release post

 

[hassanila]

@thewraith2008 I work for one of the operators in the network and I have a Motorola Tetra Radio connected to that talkgroup, I can hear very clear without any cuts in my radio but it keeps cutting in SDR#, so I don't think it's a problem with the network.
Can it be low SNR 32dB?
Or maybe bad HackRF One Device?
I can listen to FM Stereo without any cuts, so it must be the demodulation that's failing somewhere.
Or maybe my laptop? I haven't tested it in any other computer yet
Also when I change audio latency in SDR# it cuts less/more, I let it at 100ms.
I read online that it might be the usb port/cable/sdr device dropping samples, I will test it more and hopefully be able to fix it.

 

[tsapers]

SDR# AudioFilter OFF?

I see you specifically ask about this setting in SDR#. What is the correct setting? Should Filter Audio be OFF or ON?
Correct IQ, OFF or ON?
Any other best practise SDR# settings for decoder and TTT?
What is a good minimum SNR for decoding?
And is it better to have sample rate at 1.024, 2.048 or 2.4 and higher?

 

[hamradionl]

tsapers,
Lowcost RTLSDR give much noise, static, and very poor PPM !
Win10
Tested with RTLSDR-V3 - AirspyMini, RSP1A, PLUTOsdr - good hardware seem very important/critical
USB 3.0
SDR# setting
AUDIO sample rate in file SDR.exe.config set to 48000
Audio Filter be OFF
WFM 26000
freq Step 6.25
SNR 10 - 15 main NO or very poor decoding
SNR 15 - 20 some stutter + SDS faults
SNR 20 - 25 clear voice some minor dropouts + SDS
SNR 25++ very clear voice + SDS no faults
sample rate at 1.024 = low CPU % (older slow PC)
Waterfall OFF = low CPU % (older slow PC)
Bandplan OFF = Low CPU % (older slow PC)

Usefill TIP:
FrequencyManager for fast switching between different network !

.

 

[thewraith2008]

@thewraith2008 I work for one of the operators in the network and I have a Motorola Tetra Radio connected to that talkgroup, I can hear very clear without any cuts in my radio but it keeps cutting in SDR#, so I don't think it's a problem with the network.
Can it be low SNR 32dB?
Or maybe bad HackRF One Device?
I can listen to FM Stereo without any cuts, so it must be the demodulation that's failing somewhere.
Or maybe my laptop? I haven't tested it in any other computer yet

That level should be OK.
The % indicator (under the red 'Received') should show signal quality. If it's not sticking to 100% then there is a receiving issue.
A brief jump while changing carrier is OK.

The HackRF One hardware is probably not the problem.
Maybe the bandwidth. What size are you using. Are you decimating it at all?
What is you CPU usage when using SDR# with plug-in and TTT?
FM Stereo is relatively simple in comparison to demodulating/decoding a trunk network.

Also when I change audio latency in SDR# it cuts less/more, I let it at 100ms.
I read online that it might be the usb port/cable/sdr device dropping samples, I will test it more and hopefully be able to fix it.

Latency less than 100mS will most likely increase the chopping. Mine is on 100mS (default?)
Do you use other devices on the USB at same time as HackRF?
Are you using through a USB hub. Is it powered?
I know there is a tool called RTLTool for RTL devices to test USB throughput (of IQ samples) to see if iq samples are dropped a a given samplerate. Not sure if HackRF has anything like that.

I do hear problems with audio from time to time but it's hard to tell if it's:
Bad MS. Bad mic etc...
MS to BS. Poor signal into BS. This may not show up any signal errors from BS to me.
BS to me. This could be signal fluctuation (antenna moving in wind etc..) or dongle limits (heat, frontend overloading etc...).
Plug-in or some other PC issue. USB bandwidth, CPU loading etc...

The list goes on.



Latest version (v1.0.15.6) can be found here: Release post

 

[kikosgc]

tsapers,
Lowcost RTLSDR give much noise, static, and very poor PPM !
Win10
Tested with RTLSDR-V3 - AirspyMini, RSP1A, PLUTOsdr - good hardware seem very important/critical
USB 3.0
SDR# setting
AUDIO sample rate in file SDR.exe.config set to 48000
Audio Filter be OFF
WFM 26000
freq Step 6.25
SNR 10 - 15 main NO or very poor decoding
SNR 15 - 20 some stutter + SDS faults
SNR 20 - 25 clear voice some minor dropouts + SDS
SNR 25++ very clear voice + SDS no faults
sample rate at 1.024 = low CPU % (older slow PC)
Waterfall OFF = low CPU % (older slow PC)
Bandplan OFF = Low CPU % (older slow PC)

Usefill TIP:
FrequencyManager for fast switching between different network !

.

What about the Demodulator settings? What are your recommendations?

My current settings:

 

[hassanila]

@thewraith2008 Thank you for your help.

Sample rate: 8MSPS
Audio Sample rate: 48Khz 24Bit
Bandwidth: 26000
LNA Gain 40db
VGA Gain 18db

I'm using a laptop that might also be the problem.
Signal Quality is always on 100% as you can see in the sample, cpu usage with everything running 12%. Could it be interference?
It's probably my pc or USB port/cable. I don't use any usb hubs, no other usb devices plugged in, device directly plugged into laptop.

I have just bought RTL-SDR v3 and a new UHF antenna, will arrive in 5 days, I will test it and hope it works

 

[hamradionl]

kikosgc,
For me i only use Call List - Alternative generation, but these settings is your choice.
I notice while testing the Hardware that give very big difference, beside the settings. Specially attention to the noise figger.
For those low-end RTLSDR a TIP : use this RTL820 driver is made by TSSDR and have more settings for best SNR.

hassanila97,
I use 4x RTL-SDR-V3 with this driver
Use antenna with low gain to get wider bandwith, in city area between buildings that gain you will never get to work.

 

[hassanila]

hassanila97,
I use 4x RTL-SDR-V3 with this driver

Thank you, I will check it out when my RTL-SDR arrives.

 

[hamradionl]

hassanila97
driver work with any RTLSDR with the R820T chipset inside, but best with V3.