RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Computer Aided Monitoring and Programming > Software Defined Radio


Software Defined Radio - A forum for general discussion of software defined radio (SDR) receiver equipment.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 02-01-2018, 7:27 AM
Member
   
Join Date: Oct 2017
Posts: 21
Default New TETRA decoding plugin for sdr# problem

Hi,

Saw this new TETRA decoding plugin for sdr# "https://www.rtl-sdr.com/tetra-decoder-plugin-for-sdr-now-available/".
The plugin seems to work just fine and bursts are received in the MSYS2 window.
However,for some reason the newtork is not recognized properly and I can't hear anything, although I see broadcasts and traffic on the channels via the MSYS2 window.
I know that encryption is not the problem because the "Network Info" window is completely empty (parameters "Air encryption 1" or "Air encryption 2" should appear in the Network Info window, among other network data).
I see that the first CRC COMP says "ok" but the second says "wrong" in the MSYS2 window so that might be the reason, not sure.
Tried set "minOutputSampleRate" value in "SDRSharp.exe.Config" file to 32000 and use WFM / set to 48000 with NFM. In both cases windows playback set to 48000.
Still the same.
Once in a while I hear a very short sound (last less than a second), might indicating tunning error? not sure.
Posted pictures below.
Any ideas?
Attached Images
   

Last edited by yerez; 02-01-2018 at 7:39 AM.. Reason: add pictures
Reply With Quote
Sponsored links
  #2 (permalink)  
Old 02-01-2018, 7:35 AM
mtindor's Avatar
OH/WV DB Admin
  RadioReference Database Admininstrator
Database Admin
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2006
Location: Carroll Co OH / EN90LN
Posts: 6,640
Default

Quote:
Originally Posted by yerez View Post
Hi,

Saw this new TETRA decoding plugin for sdr# "https://www.rtl-sdr.com/tetra-decoder-plugin-for-sdr-now-available/".
The plugin seems to work just fine and bursts are received in the MSYS2 window.
However,for some reason the newtork is not recognized properly and I can't hear anything, although I see broadcasts and traffic on the channels via the MSYS2 window.
I know that encryption is not the problem because the "Network Info" window is completely empty (parameters "Air encryption 1" or "Air encryption 2" should appear in the Network Info window, among other network data).
I see that the first CRC COMP says "ok" but the second says "wrong" in the MSYS2 window so that might be the reason, not sure.
Tried set "minOutputSampleRate" value in "SDRSharp.exe.Config" file to 32000 and use WFM / set to 48000 with NFM. In both cases windows playback set to 48000.
Still the same.
Once in a while I hear a very short sound (last less than a second), might indicating tunning error? not sure.
Posted pictures below.
Any ideas?
One idea would be to contact the author of the plugin. Just a suggestion

mike
__________________
Mike / AA8IA
PSR500/PRO197/BCD436HP/TRX-1

Email: my username @gmail

If I PM you about a submission, please reply promptly or your submission may be rejected.
Reply With Quote
  #3 (permalink)  
Old 02-01-2018, 8:03 AM
Member
   
Join Date: Jul 2011
Posts: 107
Default

I also tried it and it worked fine. One thing that comes to my mind is that this channel is broadcasting data only. Other than that, I saw on your screenshot that you are getting only bursts in MSYS. On the network I tried I'm seeing network info also. Don't know why is this but that's the first thing I saw your post.
Reply With Quote
  #4 (permalink)  
Old 02-01-2018, 8:06 AM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by mtindor View Post
One idea would be to contact the author of the plugin. Just a suggestion

mike
Wish I could, but the author of the plugin is unknown.
From rtl-sdr website:
"The plugin doesn't seem to be officially released anywhere, but we did find it thanks to @aborgnino's tweets on Twitter, and he found it on a Russian language radio scanner forum".
There is no github repository either.
Reply With Quote
  #5 (permalink)  
Old 02-01-2018, 8:14 AM
BM82557's Avatar
Member
   
Join Date: Aug 2006
Location: Berkeley Co WV
Posts: 2,358
Default

I wonder if Filter Audio in SDRSharp should be un-checked?
Reply With Quote
Sponsored links
  #6 (permalink)  
Old 02-01-2018, 8:26 AM
Member
   
Join Date: Jul 2011
Posts: 107
Default

Mine was checked when I tried it
Reply With Quote
  #7 (permalink)  
Old 02-01-2018, 8:47 AM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by LimaZulu View Post
I also tried it and it worked fine. One thing that comes to my mind is that this channel is broadcasting data only. Other than that, I saw on your screenshot that you are getting only bursts in MSYS. On the network I tried I'm seeing network info also. Don't know why is this but that's the first thing I saw your post.
Yes I know the Network Info window should be filled with different network parameters, even if the network is encrypted.
That's why I know encryption is not an issue here, but something else.
Regarding data channels, I have lots of TETRA in my area and for all of them I have this problem.
It highly unlikely that all of them are data channels and some must be voice channels.
What version of SDR# and vc++ you use?

Quote:
Originally Posted by BM82557 View Post
I wonder if Filter Audio in SDRSharp should be un-checked?
Tried both checked and unchecked.
In checked I hear short sounds often, still there is no such a big difference.
Reply With Quote
  #8 (permalink)  
Old 02-01-2018, 9:26 AM
Member
   
Join Date: Jul 2011
Posts: 107
Default

Quote:
Originally Posted by yerez View Post
......
What version of SDR# and vc++ you use?

........
Latest version available.
Reply With Quote
  #9 (permalink)  
Old 02-01-2018, 10:32 AM
Member
   
Join Date: Sep 2006
Location: Stockholm, Sweden
Posts: 1,335
Default

It looks as if you decode something as the Netinfo text is red that indicate it decodes info and also channels seem to populate with call numbers.
The only thing is the error value 0.21 at the polarity invert that seems a bit high, and that you monitor 900MHz but upload/download frequency are decoded as being in the 400MHz range?
Are you spot on the frequency, you have calibrated the SDR sticks frequency?
I only decode properly if the SDR stick sample rate are set at 2.4MSPS in the cog wheel config.

/Ubbe
__________________
TRX-2 BCD536 HP1 BCT15 BC246 BC346 BR330 UBC3500 Pro2006 Pro2042 Optocom OS545 Scout PCR1000 ICR2500 IC75 DX394 AR8200 IC-R2 IC-R10 UBC780 MD380 CS580 CS750 Pro96 Perseus ADCR25 AcecoSC1plus RTL-SDR
Reply With Quote
  #10 (permalink)  
Old 02-01-2018, 12:40 PM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by Ubbe View Post
It looks as if you decode something as the Netinfo text is red that indicate it decodes info and also channels seem to populate with call numbers.
The only thing is the error value 0.21 at the polarity invert that seems a bit high, and that you monitor 900MHz but upload/download frequency are decoded as being in the 400MHz range?
Are you spot on the frequency, you have calibrated the SDR sticks frequency?
I only decode properly if the SDR stick sample rate are set at 2.4MSPS in the cog wheel config.

/Ubbe
Just updated to latest version 1637 of sdr# to see if that chaneged something. No luck so far
The error now is lower, between (+-)0.05 to (+-)0.11 values.
The "NETINFO" word (top left of the net info window) is red and indicates some unclear data.
Can you figure out if that a control / voice channel?
Not sure I understood your questions.
The TETRA channels freqs are at 933 - 938Mhz in my area.
Is there any difference regarding the decoding in these freqs comparing to the 400Mhz freqs?
I have calibrated my sdr sticks to that frequency manually, set the bandwidth to 25Khz and use WFM mode with 32000Hz sample rate in the "minOutputSampleRate" value at "SDRSharp.exe.Config" file.
Using 2.4 Msps in the cog wheel config.
Missed anything?
Posting below the updated pictures.
Attached Images
   
Reply With Quote
  #11 (permalink)  
Old 02-01-2018, 5:39 PM
Member
   
Join Date: Sep 2006
Location: Stockholm, Sweden
Posts: 1,335
Default

It's coded to default to the 400MHz band, the only one used in EU, but that should only make the info about the control channel frequency being displayed incorrectly and probably not make any difference to the decoding.

But didn't the instruction point out that you need to use 48kbs audio stream?
I can see that #SDRSharp sends audio to msys in a rate varying between 32kbs and 44kbs so limiting it to 32kbs migh be an issue.

/Ubbe
__________________
TRX-2 BCD536 HP1 BCT15 BC246 BC346 BR330 UBC3500 Pro2006 Pro2042 Optocom OS545 Scout PCR1000 ICR2500 IC75 DX394 AR8200 IC-R2 IC-R10 UBC780 MD380 CS580 CS750 Pro96 Perseus ADCR25 AcecoSC1plus RTL-SDR
Reply With Quote
  #12 (permalink)  
Old 02-02-2018, 4:45 AM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by Ubbe View Post
It's coded to default to the 400MHz band, the only one used in EU, but that should only make the info about the control channel frequency being displayed incorrectly and probably not make any difference to the decoding.

But didn't the instruction point out that you need to use 48kbs audio stream?
I can see that #SDRSharp sends audio to msys in a rate varying between 32kbs and 44kbs so limiting it to 32kbs migh be an issue.

/Ubbe
Well, the original instructions indeed pointed out that for WFM one need to use 32KHz output audio stream and for NFM at least 48Khz stream.
I have tried to use output stream values of up to 96Khz, because in my area the TETRA freqs are around 935Mhz.
Still no difference.
I am not sure what is the right output sampling stream for these high freqs or the sdr# upper limit.
In your case, what is the rate of output data sent to the Tetra-Rx?
Here it's between 32KB/s - 40 KB/s which is 256kb/s - 320 kb/s, so maybe the 96Khz output sampling sent to Tetra-Rx is not high enougth.
Unfotunately, trying the next step of 176.4Khz results in an error message by sdr#.
Once in a while I hear sounds when tunning to a TETRA channel, but it's too short to determine if it's a human or other metallic sound.
That's why I think the problem is has indeed something to to with the sample rates error (too low sample rate) or wrong demodulation type by the plugin, although I am not sure if there are different types of demodulation in TETRA based systems, like for example, in P25 based ones.
Reply With Quote
  #13 (permalink)  
Old 02-02-2018, 5:25 AM
Member
   
Join Date: Jul 2011
Posts: 107
Default

Quote:
Originally Posted by yerez View Post
......
The TETRA channels freqs are at 933 - 938Mhz in my area.
Is there any difference regarding the decoding in these freqs comparing to the 400Mhz freqs?
.........
Just in case, take a look around 420-428 MHz.
Reply With Quote
  #14 (permalink)  
Old 02-02-2018, 11:18 AM
Member
   
Join Date: Sep 2006
Location: Stockholm, Sweden
Posts: 1,335
Default

Tetra standard should be the same regardless of frequency band the only difference being 45MHz between tx/rx instead of 10MHz.

I also see the "CRC comp=wrong" message in the telgrams that say "ul_usage traffic" and must be the result of some coding error by the author.

The NFM WFM settings probably doesn't matter, you set the bandwidth yourself to whatever you want. It is only different memory settings for the parameters. I can use both without seeing any difference between them.

Have you tried all available tetra frequencies to see that this one isn't just some sort of special one for test during setup of the system or transfer of data only without voice?

All indicators seems to be ok in your picture but you never hear voice.

I use sample rate 2.4MSPS Quadrature sampling in SDR# for the SDR stick with audio sample 48000 sample/sec and for some reason I have 100mS latency, no filter.

Radio uses WFM with Blackman-Harris 4 filter.

/Ubbe
__________________
TRX-2 BCD536 HP1 BCT15 BC246 BC346 BR330 UBC3500 Pro2006 Pro2042 Optocom OS545 Scout PCR1000 ICR2500 IC75 DX394 AR8200 IC-R2 IC-R10 UBC780 MD380 CS580 CS750 Pro96 Perseus ADCR25 AcecoSC1plus RTL-SDR
Reply With Quote
  #15 (permalink)  
Old 02-03-2018, 7:32 PM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by LimaZulu View Post
Just in case, take a look around 420-428 MHz.
Quote:
Originally Posted by Ubbe View Post
Tetra standard should be the same regardless of frequency band the only difference being 45MHz between tx/rx instead of 10MHz.

I also see the "CRC comp=wrong" message in the telgrams that say "ul_usage traffic" and must be the result of some coding error by the author.

The NFM WFM settings probably doesn't matter, you set the bandwidth yourself to whatever you want. It is only different memory settings for the parameters. I can use both without seeing any difference between them.

Have you tried all available tetra frequencies to see that this one isn't just some sort of special one for test during setup of the system or transfer of data only without voice?

All indicators seems to be ok in your picture but you never hear voice.

I use sample rate 2.4MSPS Quadrature sampling in SDR# for the SDR stick with audio sample 48000 sample/sec and for some reason I have 100mS latency, no filter.

Radio uses WFM with Blackman-Harris 4 filter.

/Ubbe
Well, thank you guys, that was finally it.
Searched carefully around 390-420 Mhz with better antenna and found 2 TETRA networks that did not notice before.
One of them (around 393Mhz) decoded properly by the plugin with minOutputSampleRate value of 32000, audio sample rate in sdrSharp of 48000, 44100 in windows output audio settings, WFM and 2.4 MSPS.
Heard voice properly on that one.
Trying to decode the second (around 420 Mhz) results in garbled metallic sound.
Thought of an encryption in the second network but then noticed both networks has the "Air encryption" field set to 1 from what I see in MSYS terminal, and the first newtwork is decoded properly, so not sure encryption is the issue with the second network.
Maybe you have a better idea what's wrong here.
Regarding the original TETRA network (around 933-938 Mhz) I tried to decode, searched what TETRA system might that be with no luck .
Online sources reports of the following bands for TETRA based systems:
410-430 MHz, 870-876 MHz, 915-921 MHz, 450-470 MHz, 385-390 MHz , 395-399,9 MHz of the ETSI standarts.
However, this network was definitely TETRA based one that the plugin recognize but can't decode for some reason.
Have and idea of what that reason might be?
Thought of a new TETRA network that supports/combine 4G/LTE features but not sure about that.
Would be glad to figure that one out.
If so, can telive (https://github.com/sq5bpf/telive) decode that?
Thanks again for the help.
Reply With Quote
  #16 (permalink)  
Old 02-04-2018, 5:08 AM
Member
   
Join Date: Sep 2006
Location: Stockholm, Sweden
Posts: 1,335
Default

I'm beginning to believe it is only some sort of image frequency you are trying to decode.

Your ETSI source says 915-921MHz and duplex -45MHz is 870-876MHz but you have a signal at 938MHz.
But you also have a signal at 393MHz and the nationwide system I have uses 390-394MHz so the source have omitted that frequency range, so maybe the source are not to be trusted.

For high UHF band I suggest you only search in the 915-921MHz range, there shouldn't be any non standard systems out there. For low UHF the mobiles transmit at -10MHz so look in the upper 10MHz part of each band, 420-430MHz 460-470MHz 390-399MHz.

/Ubbe
__________________
TRX-2 BCD536 HP1 BCT15 BC246 BC346 BR330 UBC3500 Pro2006 Pro2042 Optocom OS545 Scout PCR1000 ICR2500 IC75 DX394 AR8200 IC-R2 IC-R10 UBC780 MD380 CS580 CS750 Pro96 Perseus ADCR25 AcecoSC1plus RTL-SDR
Reply With Quote
  #17 (permalink)  
Old 02-04-2018, 10:40 AM
Member
   
Join Date: Jul 2011
Posts: 107
Default

Just what Ubbe said. This is a "ghost" signal if I can call it like that. That's about 915-921 MHz signal.

About encryption - Air encryption = 1 means that network is able (and most probably do) encryption but this does not mean that all subscribers use encryption during calls. That's why you are able to hear voice even if air encryption = 1.
Reply With Quote
  #18 (permalink)  
Old 02-05-2018, 6:00 AM
Member
   
Join Date: Oct 2017
Posts: 21
Default

Quote:
Originally Posted by Ubbe View Post
I'm beginning to believe it is only some sort of image frequency you are trying to decode.

Your ETSI source says 915-921MHz and duplex -45MHz is 870-876MHz but you have a signal at 938MHz.
But you also have a signal at 393MHz and the nationwide system I have uses 390-394MHz so the source have omitted that frequency range, so maybe the source are not to be trusted.

For high UHF band I suggest you only search in the 915-921MHz range, there shouldn't be any non standard systems out there. For low UHF the mobiles transmit at -10MHz so look in the upper 10MHz part of each band, 420-430MHz 460-470MHz 390-399MHz.

/Ubbe
Quote:
Originally Posted by LimaZulu View Post
Just what Ubbe said. This is a "ghost" signal if I can call it like that. That's about 915-921 MHz signal.

About encryption - Air encryption = 1 means that network is able (and most probably do) encryption but this does not mean that all subscribers use encryption during calls. That's why you are able to hear voice even if air encryption = 1.

A "ghost" signal is definitely an option here.
Made some further research and apparently there are countries with TETRA systems of 915 - 933 Mhz, which could explain these wierd freqs, still considering a "real" signal.
To take into consideration the SDR gaps and a chance that the one I used fails to point the right freq, which could lead to "ghost" signals, checked this again with 3 different SDR sticks (of different manufacturers).
All of them has these wierd TETRA freqs appear. Strange.

Anyway, the plugin should still be able to decode a "ghost" TETRA signal if it was "transferred" from 915 - 921 Mhz to 933 - 938 Mhz band, shouldn't it?
This in case of a stantard system of couse.

Regarding the encryption, thanks for info.

Btw, what is is the difference between this new plugin to telive regarding aspects of sound quality and decoding none standart or additional types of systems?

Thnaks.
Reply With Quote
  #19 (permalink)  
Old 02-05-2018, 8:17 AM
Member
   
Join Date: Sep 2002
Location: Toronto, Ontario
Posts: 4,406
Default

Quote:
Originally Posted by yerez View Post
Anyway, the plugin should still be able to decode a "ghost" TETRA signal if it was "transferred" from 915 - 921 Mhz to 933 - 938 Mhz band, shouldn't it?
Not necessarily. The polarity of the extracted signal could be inverted and if the decoder does not expect that, it won't handle it. Also, the imaging process can damage the signal beyond repair; it may have noise or some non-linear transformation applied to it that renders it useless.
Reply With Quote
  #20 (permalink)  
Old 02-05-2018, 4:19 PM
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Feb 2006
Location: Cape May, NJ
Posts: 557
Default

I have it working except it mutes the volume. Is there a screen shot of what the info is suppose to look like?
__________________
BNN#13
Erma FD
Cape May City FD

Last edited by wildbillx; 02-05-2018 at 4:55 PM..
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 5:20 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2015 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions