need some explaination

fe8769 fe8769 at gmail.com
Wed Jul 8 09:09:12 UTC 2020


Thanks for all answers . I understand better now
I'll test and let you know
Pascal


Le mer. 8 juil. 2020 à 10:50, Sylvain Munaut <246tnt at gmail.com> a écrit :

> Hi,
>
>
>> this line is working fine
>>
> ./gmr1_rx_sdr.py --args airspy -a 927 -s 6000000 -B L -f 1553968750 -g 19
>> -b 40
>> then after
>> ./gmr1_rx 4 /tmp/arfcn_927.cfile
>> wireshark is giving all informations
>>
>> I have "immediate assignment on ARFCN 928 929 930 931
>>
>> I tried to do the same with 928 929 930 931
>> ./gmr1_rx_sdr.py --args airspy -a 929 -s 6000000 -B L -f 1554031250 -g 25
>> -b 40
>> with 1 Gb of datas, I can retrieve only 2 frames in wireshark
>>
>> I'm sure there is traffic on these 4 channels
>>
>
> So to follow assignments to dedicated channels, you need to use the `live`
> branch of the code and use gmr1_rv_live binary.
>
> Basically you can't decode _just_ the traffic channel (i.e. the 928 929
> 930 931 ARFCNs).  You need to first lock to the BCCH ( 927 ) and then
> follow the assignment so you have the proper alignment etc ...
> Which means you need to be receiving both channels at the same time, using
> multiple `-a` arguments to gmr1_rx_sdr.py
>
> And then you use the gmr1_rx_live binary which supports processing several
> channels in parallel and feed it all the data at once using something like :
>
> gmr1_rx_live 4 927:/tmp/arfcn_927.cfile 928:/tmp/arfcn_928.cfile ...
>
> Each of the argument after the '4' (which is the sample-per-symbol) is in
> the form ARFCN:FILE   where ARFCN is the ARFCN number and FILE is the path
> where to find the data corresponding to that ARFCN number.
>
> And then the code will be able to find the BCCH lock to it and when it
> sees an assignement command, it will look if it has a data file available
> for that ARFCN and if it does, it will follow the assignement and start
> decoding the dedicated channel as well.
>
>
>
>> Is "immediate assignment " means TCH3 and voice ?
>>
>
> Not all Immediate Assignement means TCH3/voice, they can be control
> channels or packet data or whatever else ... it just means a phone was
> assigned a dedicated channel, you need to look at what type and what mode
> of channel it is to know what it's going to carry.
>
>
>
>> I tried all branches on git hub with same result
>>
>> What is usage of gmr1_process_recording.py ? and arguments
>>
>
> So this script doesn't really "do" anything. All it does is take the
> filename of a file recorded by the osmocom_fft program (which uses a
> filename pattern that includes the center frequency and sample rate) and
> then it prints the commands you can use to process that recording. Mostly
> it's going to be two commands, the first one that will take the .cfile
> recording and split it into a bunch of ARFCN channels and then another
> command that will process all those ARFCN channels.
>
> But as I said, it won't run those commands, it just prints them, you need
> to cut&paste them and run them and/or adapt them to your needs.
>
>
>
>> What is usage of gmr1_ambe_decode and gmr1_rach_gen
>>
>
> * gmr1_rach_gen generate examples RACH bursts, it's used for internal
> testing of the c-band monitoring stuff in gnuradio
> * gmr1_ambe_decode decodes TCH3 data payloads into PCM audio
>
> Cheers,
>
>      Sylvain Munaut
>
>
>
>

--
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/gmr/attachments/20200708/71036681/attachment.htm>


More information about the gmr mailing list