Tetra decoding

[hansheesbeen]

Yes thats encryped

 

[grahampaull]

I'm seeing Air Encryption: 1 but I am hearing clear voice, if it says 1, keep listening as other users without encryption on their handsets may be using this.. I think that's how it works anyhow.


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[sm0vec]

Thanks for a really great software.

I would like to contribute with some findings which might help in future development:

1. Sometimes the receiver thread get out of sync and just reporting the error message below. This seems to happen sometimes when the signal is on the limit, but the problem is not resolved when changing to a strong signal. The fact that the 'out of sync' is not related to the signal as such can be seen when running two receivers, if I then swap the channels between the two receivers, the error still remains in the receiver that's already 'out of sync'. If leaving the receiver on a good channel for some time it can though recover by itself, but if the receiver is manually retarted it always recovers directly.

The repeated message in the receiver terminal:

BURST
*** could not find successive burst training sequence

2. It seems to be a ghost on slot 10. This slot often as it would be traffic ongoing (saying OK, but without any SSI). This means that it often blocks the live audio from real traffic on other slots (unless using s to switch) or enabling mutessi. Using mutessi is of course a easy workaround, but it seems to be something strange with this slot. I seems like the problem often appears in case of SDS messages, but I can't say for sure.



The two following cases are related to when a individual call is received (unit to unit). In this case only one of the parts can be monitored (unless they are both on the same site). The telive window works well and show the SSI on the used slot.

3. In case of individual calls no SSI is stored in the filename of the recording.

4. In case of individual calls the log file seems to miss some data. Sometimes (but not always) the used slot (IDX:xx) is logged once in the beginning of the call (FUNC-CONNECT), but during the call the SSI is only logged at IDX:000 which means that it's not possible to from the log separate individual calls on the same site (if more than one individual call is active at the same time)

regards

Daniel

 

[henrygb]

congratulations!

most people which have problems are using ubuntu, were there some additional steps that you had to do, which were not in the documentation? your answer might help a lot of people

I followed this tutorial

RTL-SDR Tutorial: Listening to TETRA Radio Channels - rtl-sdr.com

in a fresh Ubuntu 12.04 LTS, 32 bit in virtual machine vmware, the first time followed step by step, with errors in GNU Radio installation, the second time (fresh ubuntu again) first installed RTL drivers "sudo apt-get install rtl-sdr", then followed step by step again, about 8 hours to finish, and now working.

Tried the same procedure but in Ubuntu 12.04 LTS 64bits, with NO successfully instalation.
Tried with debian and nigthmare translation from ubuntu commands.

I have questions about tetra system, in a Download frequency, this is simplex mode? 1 TX at time? or many TX at time like DMR with two slots, or like a trunking system in other frequency

 

[kermit_t_f]

Short answer, because I'm mobile. Yes, TETRA is comparable with DMR, but it features 4 timeslots on a single frequency.

 

[grahampaull]

Short answer, because I'm mobile. Yes, TETRA is comparable with DMR, but it features 4 timeslots on a single frequency.

Good to know... Would 1 service, say the fire service use multiple freqs ?.. So if I monitor say 393.9125 will I hear the 2 sides of the conversation or could the other end of the conversation be on another freq ?


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[hansheesbeen]

You will hear both sides

 

[hansheesbeen]

Direct calls don't show the issi s of the radio: traffic_20141206_133104_25_0_0_0

 

[yo4tnv]

I`m looking into TEA2 specs but my math knowledge is real old and poor so, any of you guys have captured clear voice leaving system at work for several days or more on encrypted streams? Because I didn`t.. Might that be a legend ?

 

[sq5bpf]

in a fresh Ubuntu 12.04 LTS, 32 bit in virtual machine vmware, the first time followed step by step, with errors in GNU Radio installation, the second time (fresh ubuntu again) first installed RTL drivers "sudo apt-get install rtl-sdr", then followed step by step again, about 8 hours to finish, and now working.

this shouldn't work well, because there will be the rtl-sdr package, and the rtl-sdr drivers compiled from source. but maybe the rtl-sdr package adds some rules that make it work on ubuntu

the procedure on that web page is my procedure, only castrated to show only cut-and-paste (-and-don't-think) commands for a 32-bit system

Tried the same procedure but in Ubuntu 12.04 LTS 64bits, with NO successfully instalation.

this will not work with the above procedure.

please look at this document:
https://github.com/sq5bpf/telive/blob/master/telive_doc.pdf?raw=true

for a 64-bit system you will need to compile the codecs on a 32-bit system, this is described in the faq

Tried with debian and nigthmare translation from ubuntu commands..

there should be no nightmare. the commands are the same. linux is linux, same commands everywhere (with maybe a few dirrerences in package management etc).

I have questions about tetra system, in a Download frequency, this is simplex mode? 1 TX at time? or many TX at time like DMR with two slots, or like a trunking system in other frequency

4 voice channels, you can also have data other than voice. there is support for trunking (TMO), and direct radio-to-radio contacts (DMO). tetra is more like gsm actually

 

[sq5bpf]

1. Sometimes the receiver thread get out of sync and just reporting the error message below. This seems to happen sometimes when the signal is on the limit,[...]
The repeated message in the receiver terminal:

BURST
*** could not find successive burst training sequence

i'e noticed this too, will research it when i get some time

2. It seems to be a ghost on slot 10. This slot often as it would be traffic ongoing (saying OK, but without any SSI). This means that it often blocks the live audio from real traffic on other slots (unless using s to switch) or enabling mutessi. Using mutessi is of course a easy workaround, but it seems to be something strange with this slot. I seems like the problem often appears in case of SDS messages, but I can't say for sure.

wow, this is strange. i've never seen anything like this on any of the systems that i've tried, but judging from the responses that i got the systems that i hear have very little kinds of traffic.
could you send me the output of receiver1 and telive.log?

The two following cases are related to when a individual call is received (unit to unit). In this case only one of the parts can be monitored (unless they are both on the same site). The telive window works well and show the SSI on the used slot.

this is for duplex calls. if they are on the same site, then you get two recordings, on each one you can only hear one party. if they are on different sites, then you get only one recording.

but in this case i don't see anu ssis (like below)

3. In case of individual calls no SSI is stored in the filename of the recording.

i have the same problem.

4. In case of individual calls the log file seems to miss some data. Sometimes (but not always) the used slot (IDX:xx) is logged once in the beginning of the call (FUNC-CONNECT), but during the call the SSI is only logged at IDX:000 which means that it's not possible to from the log separate individual calls on the same site (if more than one individual call is active at the same time)

could you provide an example?

btw i want to fix the bugs that i can in this version. after i'm done i want to make another version with a different method of following calls, and hopefuly that one will be more accurate than the hacky version right now


thanks for your comments

 

[sq5bpf]

I'm seeing Air Encryption: 1 but I am hearing clear voice, if it says 1, keep listening as other users without encryption on their handsets may be using this.. I think that's how it works anyhow.

exactly

Air Encryption: 1 means that there is a license to encrypt (which costs $$$), but this doesn't mean that it has to be used by everyone (because it costs yet more $$$)

this is described in the telive FAQ

 

[grahampaull]

btw i want to fix the bugs that i can in this version. after i'm done i want to make another version with a different method of following calls, and hopefuly that one will be more accurate than the hacky version right now





thanks for your comments

Oh Goody!...


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[sq5bpf]

I`m looking into TEA2 specs but my math knowledge is real old and poor so,

where did you get the TEA specs? please keep in mind that TEA is Tetra Encryption Algorithm, not Tiny Encryption Algorithm (which has public specs)

any of you guys have captured clear voice leaving system at work for several days or more on encrypted streams? Because I didn`t.. Might that be a legend ?

not a legend. see grahampaull's post. i also see a system that has both kinds of traffic.

leave recording on for a week, with mutessi and logging enabled, and see if you get anything interesting.

 

[sammy3418]

Direct calls don't show the issi s of the radio: traffic_20141206_133104_25_0_0_0

Would be cool to see those issi numbers scrolling down the screen... what does the mutessi command do?

Great software

 

[sq5bpf]

Would be cool to see those issi numbers scrolling down the screen... what does the mutessi command do?

RTFM!

it will ignore usage markers which don't have any SSIs assigned (so in case of a direct call it would ignore it too unfortunately). this is useful when there is encrypted traffic, this option will help ignore it

Great software

thanks

 

[ltd_nova]

TETRA questions

In my area there is a tetra system with 3 frequencies, 394.7375 , 395.2375 , 395.7375 . Using Telive monitor, I found that the three frequencies have the same MNC and the same downlink frequency ( 394.7375 ) . which frequency should use to monitor all traffic?. or should use the 3-channel system telive_3ch. If the second option, this work with only 1 USB RTL?

 

[Marvel_63]

Hi, folks!
What changes in the blocks have to do that instead of RTL- SDR earned USRP B210? When connecting the USRP, GNU Radio recognizes it immediately loads the driver and UHD firmware, but when the GRC is no reception ;-(
Any ideas?

 

[kermit_t_f]

TETRA questions

In my area there is a tetra system with 3 frequencies, 394.7375 , 395.2375 , 395.7375 . Using Telive monitor, I found that the three frequencies have the same MNC and the same downlink frequency ( 394.7375 ) . which frequency should use to monitor all traffic?. or should use the 3-channel system telive_3ch. If the second option, this work with only 1 USB RTL?

I haven't read all the telive documentation, but it looks to me, that there ist one basestation with 3 transmitters. If this is right, then the downlink frequency shown in the decoder is the one that transmits the Main Control CHannel (MCCH). You could monitor all three frequencies to see, if the higher ones transmit all the time or only sometimes. The basestation could turn them off, if the capacity from the transmitter that shows the MCCH and three other timeslots, is enough for the traffic.
I didn't check the 3-channel receiver, but sq5bpf answers really quick, looking forward to further information!

 

[sammy3418]

SSI Data? read description on youtube video interesting find

https://www.youtube.com/watch?v=aMsRWnM1YoY&feature=youtu.be