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Thread: Portable remote controlable Tetra montitor based on a new Osmocom Tetra development

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    Lightbulb Portable remote controlable Tetra montitor based on a new Osmocom Tetra development

    I'll now describe how I made a 600 USD portable and remote controlable monitor for unencrypted Tetra networks, possible to decode up to 6 frequencies at the same time.

    I guess many already have seen this on other sites, but I start with a quick description of what made this possible (for me).

    A new modified version of the Osmocom Tetra project has now been around for over a month. The additions are made by sq5bpf, who made some fixes and also added monitoring software which shows the ongoing traffic (GSSI and SSI), giving live audio, recording and logging the traffic. Only unencrypted traffic can be monitored, but some information is also shown about encrypted systems, like the CCK-ID (Common Chipher Key) and LA (Location Area), which both are interesting in order to get a better understanding on how the system is setup.

    With this modification, the Osmocom Tetra project has become easy to use for anyone with some basic knowledge in Linux.


    The source files can be found here:

    https://github.com/sq5bpf

    And the RTL-SDR site gives a good guide on how to get it up and running:

    http://www.rtl-sdr.com/rtl-sdr-tutor...adio-channels/


    I played around a bit with this software and I also made some small modifications for my need, and inspired by how good it worked I made a little project over the holidays.

    The project
    What I wanted to get was a concept for a small tetra monitor for remote access to a reasonable cost, possible to place at friends or other remote locations (without creating too much annoyance).

    Running it on a modern PC (laptop or stationary) is of course no problem, both in a native linux installation and under VMware, but how to make it more portable. But the PS is too big, and not really suitable for unattended remote locations.

    Attempt 1 - Old laptop
    First I tried to install the software on a 7 year old Laptop running Ubuntu. This worked, but I could only decode sites with two channels, and since many Tetra-sites have 4 channels I wanted to get something better, and also smaller than a laptop.

    Attempt 2 - Cheap Intel NUC
    The next item to test was the cheap NUC from Intel; DN2820FYKH

    For quite exactly 300 USD I bought a new NUC, including a 120 GB SSD drive and 4 GB RAM. With the size of only 116.6 mm x 112 mm x 51.5 mm, it more met my requirements. This box with Lubuntu linux (to reduce the GUI overhead coming with Ubuntu) worked better than the old laptop, but it still required some modification of the gnuradio code to get a good decoding of 4 frequencies at the same time. And when running 4 channels the CPU was quite taken ot it's maximum, making it different to also do remote connections at the same time.

    Another problem with this NUC is that it needs a physical monitor connected to boot up. I found several discussions about this on internet, and it might be possible to downgrade the BIOS to get this working, but I haven't tried that yet. Being able to run the box without a monitor connected is kind of a mandatory requirement if wanting to have something portable only for remote control.

    Attempt 3 - A better and more expensive Intel NUC
    I then tried the big brother NUC, the Intel NUC D54250WYKH which has the same physical size but a lot stronger CPU, an i5 4250U. With more power the cost also increased, so this setup costed 600 USD in the end (this also included a WiFi card which was included in the cheaper NUC but not in this more expensive)

    With the stronger CPU I now get a performance sufficient to sites with up to 6 different frequencies within 2 MHz, however I haven't seen many 6 channel sites so normally running only 4 channels I'll have sufficient margin in CPU power.

    I was also happy to find that the D52425WYKH worked just fine without a monitor connected. When the network is setup it's just to boot the box and it's available for remote control. I’m using X11VNC which is quite efficient in terms of CPU and network load for the remote control. However it's difficult to connect via X11VNC for the first time in a new network (not knowing IP address). This can though be solved by using TeamViewer first connection and network setup, and then connection via VNC when the network is fixed.

    Summary and next steps
    To summarize; with the software described above, an RTL-SDR dongle and a NUC for 600 USD I have got a remote controlled 6 channel Tetra Monitor (live and record audio)... smaller and a lot more capable than most analogue desktop radio scanners available.

    The next step will probably be to try remote control via a 3G dongle, which would simplify the network setup, making it completely independent on any hands on operation, only plug and play.

    Since it's an open source project I also have some ideas about more modifications for my own use, but I'll wait to see if sq5bpf doesn’t have more good surprises in the pipeline.


    More information about the NUC's I've tested
    http://www.intel.com.au/content/www/...n2820fykh.html
    http://www.intel.com/content/www/us/...54250wykh.html

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  4. #2
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    Default Re: Portable remote controlable Tetra montitor based on a new Osmocom Tetra developme

    I compiled it today on Kali. It works
    Thanks!

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    Default Re: Portable remote controlable Tetra montitor based on a new Osmocom Tetra developme

    hi kdst!
    would you like to share this on h ackaday.com?
    Last edited by nintrew; 2015-01-09 at 02:09 AM

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    Default Re: Portable remote controlable Tetra montitor based on a new Osmocom Tetra developme

    Time for an update, 9 months after the original post.

    First I would like to send thanks to SQ5BPF who continue to update his Telive software (addition and modification to Osmocom Tetra). With the latest development there have been various good enhancements. One of the features I like the most is the ability to show the information about neighboring cells of a Tetra site, which makes it even easier to explore a network and find new frequencies. The reception of SDS (text messages) and LIP (GPS location) has also been implemented and improved since my last post.

    Please also note that he also have made some scripts which makes the installation quite simple also for linux beginners.

    The set of software can be found here:
    https://github.com/sq5bpf

    Since everything is published as open source, it's easy to play around and enhance the software to your own needs. I've done quite a lot of extra implementation and logging.

    My remote monitoring station
    As I mentioned in the previous post, I aimed to do a remote controlled setup. This is now done and works just fine. I’ve since a couple of months had a remote station to monitor a system too far from my home location. I access this using TeamViewer which also allows me to download the recorded traffic.

    With the exception of an external power blackout, the system has worked just fine without any need of maintenance.

    http://www.forumbilder.se/ECH10/nuc1.jpg
    http://www.forumbilder.se/ECH10/nuc2.jpg

    What you can see on the pictures is the following:

    • Intel NUC D54250WYK - I5-4250U – about 280 USD (excluding memory and hard drive)
    • SDR - RTL SDR T2 – about 10 USD on ebay
    • SIRIO WY380-2N 380-440 MHz 3 element antenna – about 120 USD

    With the good will from an old friend, this is installed in an over 100 year old shed located about 10 km from the system I want to monitor, giving me a steady good signal. The site I monitor have 4 traffic channels, with over 1400 individual calls during a normal day. In the Telive software it's though possible to give alias names to talkgroups and also filter out uninteresting traffic (talkgroups or individual radios), with makes the large amount of traffic easier to handle.

    New NUC tested
    Since my last post, Intel has also released a new line of NUC’s.

    I was curious to see the performance difference so I bought the new unit called Intel NUC 5i5RYH i5-5250U (http://www.intel.com/content/www/us/...nuc5i5ryh.html). This i5 CPU version is now the mid-range NUC, but my tests shows that it well over perform the last years high-end version. With the 5i5RYH it’s possible to without any disturbance monitor more than 6 individual channels, which could be a mix of small systems (ie. 6 individual systems, or sites with multiple channels, like 2+4 or 2+2+2 channels).

    It’s though important to know that the new range of NUC doesn’t work with previous versions of Ubuntu Linux, so you must run at least Ubuntu/Lubunt 15.04.

    The later version of Telive also supports using Gnu-radio 3.7 and Airspy. Using the Airspy SDR receiver actually give quite a lot better reception than the cheap RTL SDR dongles. Especially in environments with a lot of strong signals, the Airspy excels. http://airspy.com/

    With Airspy it’s easy to monitor signals within 2,5 MHz bandwidth at the same time, compared to 2 MHz for the RTL-SDR. Airspy should in theory even be able to monitor signals within 10 MHz, but that bandwidth seems a bit high for the small i5 NUC. Maybe it works better on this years high-end i7 CPU variant.

    So if you are curious to see what Tetra systems you have near by (or remote), the NUC with Telive makes it quite easy to get started.

  7. Thanks Stantheman, morgan306, moj920 thanked for this post

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