tetra August 2011

tetra@lists.osmocom.org

9 participants
5 discussions

djx11 alternate
by Graham Palmer 20 Aug '11

20 Aug '11

Hi Pep. I am using the djx11 in I/Q mode with fcdp-tetra_demod.py. I leave sample rate @ 96000 but low-pass filter (-L) 12.5Khz (gr firdes lp filter in complex gives + - 12.5khz = bandwidth of 25khz). this gives me excellent constellation and works fine on demod. I hope this helps. Regards. Graham.

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small patch for float_to_bits and tetra-rx
by ciaby 17 Aug '11

17 Aug '11

This patch just convert read/write into fread/write, which are buffered and a bit faster... (actually, quite a lot faster) :-) It works, have been tested at the CCC, and allow osmo-tetra to run in real-time on a crappy Atom CPU. Btw, if you like to run the entire decoding chain in real-time, just do this (assuming that you use the funcube dongle): cd src/demod/python mkfifo out.float mkfifo out.bit ./fcdp-tetra_demod.py -D hw:1,0 -c <offset> -o out.float //(normally the fcdp runs on the second alsa port, change it to the appriopriate one). ../../float-to-bits out.float out.bit ../../tetra-rx out.bit I'm still not 100% sure about the speech decoder, but i don't have any good sniffer dump with speech traffic to test it, i will let you know in a week or so... Happy hacking! :-) Ciaby P.S. I have a plan to convert the float-to-bits code into a proper GNU Radio module, shouldn't be too difficult, is there any interest into continuing this project? As I understood Harald is quite busy with other stuff (and rightfully so), but I think that we should move forward. Volunteers? ;-)

4 5

alternative to funcubedongle?
by Mccauley 14 Aug '11

14 Aug '11

After difficulty buying the funcubedongle i think i have found a possible alternative piece of hardware. Maybe even works better than FCD given a lot of people is reporting that the dongle is sensitive to overloadis sensitive to overload. It's a traditional radio-scanner receiver that provide a built in I/Q output for use with SDR software. http://www.thiecom.de/alinco-dj-x11.html http://www.hamradioscience.com/2011/06/alinco-dj-x11t-review/ Given I/Q connected to sound card, ¿would this work directly with fcdp-tetra_demod.py? -- <>

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osmo tetra
by toto titi 13 Aug '11

13 Aug '11

hello from France Great job you did for Tetra decode . I have a request concerning : ./src/float_to_bits /tmp/out.float /tmp/out.bits | ./src/tetra-rx /tmp/out.bits where can I find float_to_bits ? where can I find tetra-rx ? thanks for answer best regards -- fe8769(a)operamail.com -- http://www.fastmail.fm - Faster than the air-speed velocity of an unladen european swallow

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Fwd: a question about Tetra
by Harald Welte 02 Aug '11

02 Aug '11

maybe somebody wants to reply... -- Sent from a mobile device, excuse my short response vahid jahandideh <vahid_jahandideh_1998(a)yahoo.com> wrote: Hi Dears This is v.jahandideh a communication engineering student. I am studding TETRA protocol and i need your help. i want to know how we can distinguish voice traffic for a specific subscriber, can we do it by extracting the AACH and then looking to the header in AACH and associating a traffic usage marker whit each individual down link conversation. or there exist another solution for this problem. I would be appreciated if could make time to reply to my inquiry. sincerely yours v.jahandideh

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tetra August 2011