Tetra decoding

[grosminet]

Some french transportation networks are using Simplex /half duplex or full duplex . In some cases, you won't be able to listen to both sides because uplink and downlink are not on the same transmitter .
SAE tetra communications are based on TETRA SDS but not readable with telive software
On many networks all voice and data trafic aren't splited over the all network but only on some cells . Some talkgroups are for the complete network like general annoucement , some only under the bus or metro lines transmitters

 

[Matof35]

Thank you "grosminet" for your answer.
Indeed, I happen to see the SDS messages in the log of Telive. The latter partially decodes the sent messages. I have already tried to listen to the 10MHZ frequency below the main frequency, yet I do not hear anything, there is not a frame. Voice traffic that is sent over the entire network is on the same frequency as individual calls. But then, why is it possible to hear regulators when making an individual call?

 

[grosminet]

Because individual call are DMO in TMO infrastructure .

 

[Matof35]

Ok I understand now

 

[Matof35]

But then, how come I sometimes hear (truly weakly) the voice of the driver in an individual call?

 

[Matof35]

Ok I understand now

But then, how come I sometimes hear (truly weakly) the voice of the driver in an individual call?

 

[CanesFan95]

I thought TETRA systems were encrypted? What is the benefit of decoding TETRA when it's encrypted?

 

[ET-NL]

I thought TETRA systems were encrypted? What is the benefit of decoding TETRA when it's encrypted?

Tetra systems CAN be encrypted, but most systems are just plain Tetra without encryption.

 

[oz1jua]

StrTelive

I have created a GUI program that can start Telive.
If some would like to try out this GUI program, it can be retrieved from the following address: https://github.com/oz1jua/StrTelive

 

[grosminet]

I have created a GUI program that can start Telive.
If some would like to try out this GUI program, it can be retrieved from the following address: https://github.com/oz1jua/StrTelive

What is the purpose of this program ? assuming telive can be run in an easy way .

As I said for years now , the best way to monitor TETRA is to use Funcubepro + +QTHID + telive . You set the exact frequency on QTHID and gain and it is starting immediatly .

We you use an airspy or RTLSDR , we have to set frequency, gain , and most of the time , we have to take many time to ajust settings (and poor level signals) to decode TETRA .

The best way would have to use GQRX or cubicsdr as a front end and send IQ results to telive . I asked to both developpers many years ago , to adapt their IQ output for TETRA but without any success .

 

[oz1jua]

What is the purpose of this program ? assuming telive can be run in an easy way .

As I said for years now , the best way to monitor TETRA is to use Funcubepro + +QTHID + telive . You set the exact frequency on QTHID and gain and it is starting immediatly .

We you use an airspy or RTLSDR , we have to set frequency, gain , and most of the time , we have to take many time to ajust settings (and poor level signals) to decode TETRA .

The best way would have to use GQRX or cubicsdr as a front end and send IQ results to telive . I asked to both developpers many years ago , to adapt their IQ output for TETRA but without any success .

I have never been a fan of Funcubepro. I use AirSpy becouse I have transmitter under 100 meter from my receiver that send with 50 Watt. This can destroy every receiver. But AirSpy run perfect under these condition.
But the main purpose of this program is a simple start Telive Receivers and Tetrad when testing lots of receivers and freq.
In my City in close we have about 50-60 sites with different freq. and different networks. And to create script for starting all this is cumbersome. What I do is to use this program to start Telive with Receivers and then start allready setup GRC compile to pyton code. Below is a Picture of my program.

 

[sq5bpf]

i've been to a radio conference today, and some nice people let me play with their tetra equipment there, and play with status messages.

i've pushed a simple update for osmo-tetra-sq5bpf to parse D-STATUS messages

in the logs this will look like this:
FUNC: DSTATUSDEC SSI:1111 SSI2:2222 STATUS:9876 RX:1
(status 9876 sent from 2222 to 1111, note that i assume that the calling SSI is a simple tetra address)

and in tetra-rx output it will look like this:
CPTI:1 CalledSSI:1111 CallingSSI:2222 CallingEXT:0 Status:9876 (0x2694)

the status messages are unique to the network.

common ones:
0 - Emergency (orange panic button on a motorola handheld radio)
65024 - reply when the called device acknowledges receiving a status message
65028 - reply when the called device doesn't exist (bad SSI etc). motorola shows "destination not found"
65029 - not sure what this is, but also an error message. got this a few times when the message was sent to a wrong address

replies are sent with calling ssi 16777213

now i could make a modification to have the status messages appear also in the telive status window, but i'm not sure if it might produce to much output. could people with busy tetra networks test the patch and see what is the maximum amount of status messages in one minute?


EDIT: other status messages are in this document on page 148: http://aeroflex-cdip.ru/eng/pdf/3900-manual3.pdf

 

[sq5bpf]

No, I would be 99.99% sure this won't run on an RPI. Tetra is pretty resource hungry.

actually one channel runs fine on a rpi 3

you could probably do two, and maybe stretch this to three with some audio hickups

 

[sm0vec]

now i could make a modification to have the status messages appear also in the telive status window, but i'm not sure if it might produce to much output. could people with busy tetra networks test the patch and see what is the maximum amount of status messages in one minute?
[/url]

Thanks, I've tested on a quite busy network, but it's not too much status traffic. Maybe something every 5-10 minutes on the site I checked.

All status messages so far has been 65024. Also in all cases so far the SSI has been the mobile station id, and the SSI2 a GSSI (group). This was the same on two completely independent systems.

 

[passie101]

@oz1jua, can you share your program ? It look very handy with multiple sites en receivers

 

[oz1jua]

@oz1jua, can you share your program ? It look very handy with multiple sites en receivers

I have already done this. But here it is: https://github.com/oz1jua/StrTelive

 

[oz1jua]

Thanks, I've tested on a quite busy network, but it's not too much status traffic. Maybe something every 5-10 minutes on the site I checked.

All status messages so far has been 65024. Also in all cases so far the SSI has been the mobile station id, and the SSI2 a GSSI (group). This was the same on two completely independent systems.

A have also testet on 2 sites on same network and on one site it only give same result 5-10 minutes.
The other site it give 0.

It still could be nice to know what is ISSI and GSSI. I know it is not simple to implement from SSI.
I have try to se what different in the hex dump off SSI but cant se the differen in SSI.
So that have to be done in the osmo core code. I have a system I know what is the GSSI and ISSI.
And that system we can use to check against if this is any help.

 

[paulania]

Hi,

Thanks for making this software!

I'd like to ask a question about the time between a call is made and it gets recorded as OGG.

Taking a look inside the "tetrad" script, I can see there's a sixty second sleep at the end, following a find for the files modified more than two minutes ago. So, would lowering the sleep make the files to get encoded sooner, or is it not enough?

Thanks in advance

 

[CqDx]

Hi all

I have been trying to set up two RTLSDR receivers to monitor two different network . However both rtlsdr reports the same device ID when I use the lsusb command. Is there a way to “force” one instance of gnuradio to use a particular rtlsdr receiver?

 

[EA8DEP]

KML Formatting

Hello!
I don't know if you remember me. I helped you to fix a bug with the locations. So much time ago.
Now I need a little modification, but I don't know where or how to do it. I need that my KML files generated by TELIVE use the SSI Alias instead of the SSI for the name of the marks.

How can I do it?

I leave a photo so you understand better what I need to do.

73