support with Grgsm voice decoding

[Snehasish Kar]

Hello

I captured some gsm data in a cfile on decoding it with grgsm_decode in time slot 1 I see a assignment command at timeslot 3 (Snapshot attached for reference), but when I decode it using grgsm_decode, i see the out file empty. I have attached a snapshot of the command. Please help me with it.

BR

Snehasish

[Piotr Krysik]

W dniu 01.06.2017 o 22:51, Snehasish Kar pisze:

Hi,

Try to change codec to one from the list that you got in the Assignment
Command with option -d and please let me know if it works.

--
Best Regards,
Piotr Krysik

[snehas...@vehere.com]

Hi I tried changing, but it didn't help. When I start decoding with TCHF it keeps on running, but doesn't give me the voice file.

[Piotr Krysik]

Hi,

One more question: did you try AMR12.2, AMR7.4 and the last one that is
not visible on the attached screen-shot of the assignment command
(AMR5.9, AMR5.15 or AMR4.75)?

But most probably AMR support in gr-gsm requires some work.

Best Regards,
Piotr Krysik

W dniu 18.06.2017 o 13:53, snehas...@live.com pisze:

[Snehasish Kar]

Yes, I tried all. Now basically I am trying to copy the same from osmocombb and openbsc and connect it with it.

BR
Snehasish

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[Piotr Krysik]

Hi,

There should be channel codes decoding in (among them AMR) libosmocore
ported by Vadim Yanitskiy from Osmo-trx. So if you want to use better
implementation of AMR decoding I would advise you to use this. You won't
need to copy any code - only link to a library from libosmocore.

If you succeed you can send pull request of your changes. It would help
me to focus on other gr-gsm related topics (like adding packages or
improving the receiver).

Best Regards,
Piotr Krysik

W dniu 04.07.2017 o 23:30, Snehasish Kar pisze:

[Snehasish Kar]

Ok I will try that.

BR
Snehasish

> On 05-Jul-2017, at 10:34 AM, Piotr Krysik <ptrk...@gmail.com> wrote:
>
> to

[tcall...@gmail.com]

hello
im new to this field , trying to sniff sms and calls over air .
can anyone assist me in getting voice calls using wireshark?
help will be appreciated

[snehas...@vehere.com]

Can you ellaborate please.

[Piotr Krysik]

Hi,

As for getting GSM voice out of wireshark - it isn't possible as far as
I know. At least I haven't done that.

To get started quickly with voice decoding you can try to do (from
gr-gsm's directory):
#this will download examples and test data
git submodule init
git submodule update

cd examples/voice_decoding_in_grc
gnuradio-companion tch_f_reception.grc &
#generate python file with F5
tch_f_reception.py

You should hear voice decoded from the recording.

--
Best Regards,
Piotr Krysik

W dniu 04.05.2018 o 10:17, tcall...@gmail.com pisze: