Tetra decoding

[jlxsolutions]

So i have a got a weird Problem when listening to more then 4 freqs in an hour or two. even signal is still the same decent, it just ends up receiving Burst sync errors and it becomes unhearable.
hardrive does not seem to be filling up either so it is not the same "bug" i encountered in a vm runnning Kali, Running on a i3 3,3Ghz dualcore 4gig Ram debian 8.If i kill the process and start it over it works fine again for a while, Thou i think this is related to the New tetra repeaters in my area because 2 of them can cause same issue even running solo the one they "renewed" first is not even on the list anymore because even the signal is around -45dB to -50dB range after a while "cannot find sync burst" errors only.
Gonna try and see if there is some of the new ones on list and get back to here (receiving 10 freqs at the moment)

 

[racingfan360]

>So i have a got a weird Problem when listening to more then 4 freqs in an hour or two.
Wonder if this is a problem with your SDR dongle drifting off frequency and losing sync as it gets hot?

 

[jlxsolutions]

>So i have a got a weird Problem when listening to more then 4 freqs in an hour or two.
Wonder if this is a problem with your SDR dongle drifting off frequency and losing sync as it gets hot?

its cooled (its also only 8celsius inside lol) and the frequency display looks the same so i doubt it.

 

[passie101]

I have the same problem when I lissen to 4 or 5 carries, I also get the burst error after random time on random receiver.
It is not the freq drift of the RTL some times only one reciever get the burst errors.

Some times it runs 24 hours without problems sometime it 15 minutes.

 

[Marco192]

Hello!

A total linux beginner here, and an "analog" HAM operator try to understand the digital world.

Somehow I managed to install and run all the necessary programs to receive tetra, but when I try to run the flowgraph the FFT window shows for a few seconds and then it crashes (turns to black&white).
edit: when I kill the flowgraph and turn it back on ... the FFT window doesn't show again. Only when I restart the machine

I am using Ubuntu 14.04 32 bit on vmware player (4 cpu, 4 gb ram). Installation was done using the install script ... tnx sq5bpf.

Thanks in advance for your help!
Kris

 

[Marco192]

Just an update ... made some progress with maximum number of cores (6), but when everything is running the fft control window still gets frozen (turns to b&w) when decoding a signal. I can only change freq. and ppm at the start, and even then it's sluggish. Is that normal, and what can I do to make it faster??

Decoding is running despite of the frozen control window, without any evident error messages but I only record very short (1-2 seconds max) voice massages that seem to be encrypted. I am not sure if the whole sistem is encrypted or if there is a problem with decoding the signal due to a slow system. (I have a phenom 1090t procesor with 20gb ram)

Thanks for your help!

 

[racingfan360]

>but I only record very short (1-2 seconds max) voice massages that seem to be encrypted. I am not sure if the whole sistem is encrypted or if there is a problem with decoding the signal due to a slow system

The short indecipherable voice recordings sounds what typically will happen when the system is overloaded. The Terminal Window will show you if Air Encryption is actually enabled (1) or disabled (0).

 

[Marco192]

The short indecipherable voice recordings sounds what typically will happen when the system is overloaded. The Terminal Window will show you if Air Encryption is actually enabled (1) or disabled (0).

I didn't expected that the decoding will be so demanding on the system. From what I read here people are decoding on even slower processors. Maybe my VM settings are not ok ... any suggestions on how to modify the settings (more ram or some other internal settings) ?

 

[jlxsolutions]

I didn't expected that the decoding will be so demanding on the system. From what I read here people are decoding on even slower processors. Maybe my VM settings are not ok ... any suggestions on how to modify the settings (more ram or some other internal settings) ?

Ubuntu 14.04 32 bit Thats your problem right there tis heavy in VM (otherwise too)
Try debian or something with the lxde desktop

 

[EricCottrell]

I didn't expected that the decoding will be so demanding on the system. From what I read here people are decoding on even slower processors. Maybe my VM settings are not ok ... any suggestions on how to modify the settings (more ram or some other internal settings) ?

Hello,

More RAM may help if the system is swapping out memory to disk. Stock Ubuntu also runs a bunch of tasks, so you can also reduce the memory and processor requirements by using a more lightweight version, like Lubuntu.
lubuntu | lightweight, fast, easier

Some VMs have a setting for the number of cores to use for the virtual processor. This is okay if the computer only has two cores since one core can be running the host OS and the other core can be running the VM. You can try 2 virtual cores if the real processor has four cores.

73 Eric

 

[EricCottrell]

Hello,

I forgot to mention that more physical RAM may be required, depending on how much physical RAM is available for use by the VM. You could slow down the system by allocating more memory in the VM than physical memory available. You may need at least three gigabytes, or need to run a 64 bit host OS and have four or more gigabytes.

I tend to max out my laptops, so they have either 8 or 16 gigabytes of physical RAM.

73 Eric

 

[Marco192]

Guys, thanks on your help. I installed debian and there is no more freezing ... everything seems to be running as it should.

Could you please listen to this short recording and confirm to me that I am listening to encrypted tetra voice comm
https://www.dropbox.com/s/v2qszk1qlfqvsge/traffic_20151228_134404_57_0_0_0.ogg?dl=1

Thanks!

 

[racingfan360]

>Could you please listen to this short recording and confirm to me that I am listening to encrypted tetra voice comm

Yes, can confirm that sounds like encryption as I've heard on other TETRA channels

 

[sm0vec]

Hello,

More RAM may help if the system is swapping out memory to disk. Stock Ubuntu also runs a bunch of tasks, so you can also reduce the memory and processor requirements by using a more lightweight version, like Lubuntu.
lubuntu | lightweight, fast, easier

Some VMs have a setting for the number of cores to use for the virtual processor. This is okay if the computer only has two cores since one core can be running the host OS and the other core can be running the VM. You can try 2 virtual cores if the real processor has four cores.

73 Eric

Btw... I recently tried installing Lubuntu on VMware, it could be installed, but after using it for some minutes it completely freeze and the virtual machine was corrupted. After changing to the same version of Ubuntu it though worked just fine.

 

[Marco192]

Yes, can confirm that sounds like encryption as I've heard on other TETRA channels

I was hoping that the encryption was only on private calls or similar ... but it's on the entire network

In theory ... can something be done about the encryption? I don't know much about it, but I assume that in it's "simple" form it's some sort of a shared key (one key for the entire network)

 

[racingfan360]

I was hoping that the encryption was only on private calls or similar ... but it's on the entire network
In theory ... can something be done about the encryption? I don't know much about it, but I assume that in it's "simple" form it's some sort of a shared key (one key for the entire network)

Likely to be TEA2 encryption and from my limited knowledge this is unlikely to be a simple encryption scheme. I very much doubt that you'd get anywhere with tackling it.

 

[tripadvisor]

Interesting. CPS Plus is not directly intuitive to use. Did you use a ready prepared code plug or you started from scratch?

How did you setup the frequency list? did you use the list of fixed frequencies, or scan list?

(sorry for a bit of topic)

It took some time to understand where to put those parameters, but I managed to program without any problems. I just entered frequencies from the telive list and programmed MCC/MNC and that's it.

 

[welshevo]

hey all... ive run the install.sh script and read the manual however when trying to run the ./receiver1 i get permission denied? but ive changed ownership of files to my user?? ive also noticed alot of instructions refer to receiver1 1 ?? i dont have this file? just receiever1 if anyone could shed some light that would be amazing! thank you

 

[jlxsolutions]

Make sure you also made it executable (tiny tick in user rights tab).
Also while somemight frown on upon starting it like the way im gonna show you here it goes
Make textfile named runtelive on desktop put the following in it.
------------------------------------------------
#!/bin/bash
cd /(yourusername)/tetra/telive
/usr/bin/xterm -font fixed -bg black -fg white -geometry 203x60&
cd /(yourusername)/tetra/osmo-tetra-sq5bpf/src
./receiver1 1&
cd /tetra/bin/
./tetrad&
gnuradio-companion
----------------------------------------------------
also make this text file executable in many Linuxes you then just double click and choose run in terminal(other wise open terminal and navigate to the file and do ./runtelive)
This should then startup everything once the xterm window pops up type in it ./rxx
and in gnuradio choose the telive_1ch_simple_gr37.grc

 

[welshevo]

jlxsolutions- i dont have the receiever1 1 file? just the receiever1 ... and all the needed files are checked as ticked to run as execs...but will try the script! see if that makes any difference....but i still get the permission denied errors also!!